Edmund E. Jacobitti
It is sometimes forgotten how young a discipline evolutionary biology is. Right up to the last part of the nineteenth century, the fixity of species was accepted by most biologists and by common sense. Any goatherd knew that there were true breeding species and that intermediate species were non-existent. That is why Linnaeus’s classification system was accepted and Ovid’s Metamorphoses was regarded as irreverent and scandalous.
Then in 1859, Darwin introduced the astonishing idea that all living things, from the simplest to the most complex, had a common ancestry, that a single species had somehow metamorphosed into another and another ad infinitum until the entire globe was filled with countless millions of distinct flora and fauna. The notion that the natural world had immanent and terrestrial causes rather than miraculous ones is so much of a common place today that it is difficult to believe the idea really only began to take hold a century ago and that it rocked nineteenth and early twentieth century thought. In this essay, I will try to sort out several schools of thought that address the problem of how one species became many.
The Passage from Darwinism to Neo-Darwinism
Darwin’s theory of common origin for all organisms began the marriage of evolution and paleontology. Paleontology was the study of prehistoric forms of animal and plant life through the study of fossils. If Darwin’s theory of evolution was correct, then the fossils studied by paleontologists ought provide empirical evidence for the theory. Suggesting that evolution could be documented with fossils, however, provided no theory of evolution. To make paleontology more than descriptive bone collecting required marrying it to a biological explanation of speciation.
But if paleontology was a discipline still in its infancy, biology was a field only in adolescence. What brought biology, ever so much more complex than physics and chemistry, out of this early stage was the discovery of genetics, the keystone of modern biology and of evolution. The rudiments of genetics had been discovered in 1866 by Darwin’s contemporary, Gregor Mendel (1822-84) but no one paid much attention to it.
Though Darwin was a creative genius, even he had only a partial explanation of how evolution occurred. He was convinced that adaptation to the great variety of earthly environments played some major role in the evolutionary process. Some individual variants within a species, he thought, were better suited to survive in one time or place than others. The “unfit” went extinct or migrated, while those that adapted gradually became new species. Furthermore, from a reading of Thomas Maltus’ Essay on Population (1837), he had run across the phrase “survival of the fittest” and concluded that it was this principle that nature “used” when selecting variants for survival. But, without genetics, Darwin had no way to explain where the variation within a species came from--and modern genetics was still a generation away.
Darwin, therefore, was forced to accept the common notion of the time, that traits in offspring were an average or a blend of the traits of the parents. Males and females certainly had different sexual characteristics, but those were the exception. Non-sexual characteristics, it was assumed, operated according to what Darwin called pangenesis where the genes (“pangenes” as he called them) of each parent (say the gene for tallness) blended evenly with those of the other parent (say the gene for shortness), to produce a person of average stature. But had that idea been correct, variation would have ended since everything would soon average out and every unique characteristic would disappear like a drop of red paint in a bucket of white.
Aware of this, Darwin, tried to explain the constant appearance of variation by appealing to another common idea, namely, that the use of an organ by certain variants within a species would ensure that the organ or part would be passed on. “There can be no doubt that use in our domestic animals has strengthened and enlarged certain parts, and disuse diminished them; and that such modifications are inherited.“ The idea seemed to fit with natural selection for if a variant found a certain organ useful in the struggle to survive, natural selection would, it seemed, retain the organ. The idea was remarkably like that of Lamarck who suggested that characteristics acquired during adaptation to the environment must be passed on to the next generation. When August Weismann famously proved that wrong (by cutting the tails off generation after generation of mice without ever bringing about the birth of a mouse without a tail), fixity of species seemed to acquire a new life.
It took another generation before Mendel’s ideas were revived in the work of Thomas Hunt Morgan, August Weismann, Hugo De Vries, and others. Mendel had presented a kind of atomic theory of heredity in which parental genes did not blend but retained their individual integrity in the offspring. Some genes were expressed; others remained dormant, but genes did not blend out. Instead, each parent provided a complement of its unique genetic units to the fertilized egg, half from the male and half from the female. Mating of even one female with several males would thus produce great variation and generations of mating would produce a breathtaking number of variations.
Even though it was not until 1953 that James Watson and Francis Crick identified DNA as the material that composed the genes, the discovery of the genetic cause of variation within a species lay the foundation for the synthesis of laboratory genetics and evolutionary theory known as Neo-Darwinism or the Neo-Darwinian Synthesis. Many figures--for example, C. D. Darlington, Theodosius Dobzhansky, Sir Ronald Fisher, Viktor Hamburger, Julian Huxley, Ernst Mayr, G. Ledyard Stebbins--contributed to this synthesis which occurred in the second quarter of the twentieth century and which remains for most thinkers the foundation of modern molecular biology.
Marrying genetics and evolution led to a number of provocative insights: that all the genes in a species population, the so-called genome or gene pool of a species, give that species its distinctive morphology and character; that nature at certain times and in certain places selects or rejects certain of a species’ characteristics; that evolution could be defined as a change in the species’ gene pool leading to a change in the characteristics or attributes of a species.
Even with these insights, however, there remained (and there still remains) a large number of puzzles about exactly how speciation occurs. For example, are there other mechanisms involved in speciation besides natural selection? Is speciation a sudden occurrence producing a variant so different that it is clearly another species or is the process more gradual? Do genes always retain their integrity and if so, how could new species come from variation within a species? What is the role of sexual selection in mating? What is the role of isolation that Darwin emphasized in the Galapagos?
The Complexities of Variation and Evolution
As is often the case, answers to complex questions lead not to closure but to more questions. The early idea that random mating of genes produced variation which natural selection then acted upon got much more complicated after the first two decades of the twentieth century, Not only was natural selection found to be much more complex than at first thought, but other forces and mechanisms were seen to play equal roles in evolution.
To understand the various schools of contemporary thought on speciation and evolution, a rudimentary knowledge of the actions and interactions of the mechanisms of evolution is necessary. For evolution to continue, there must a source of continued variation but also a limit to that variation. The forces that are thought to prevent runaway variation are (1) gene drift and (2) natural selection or adaptation. The forces that are now thought to promote variation are (1) gene flow, (2) gene mutation, and (3) gene recombination.
Negative forces in Evolution
The first force identified with speciation was adaptation through natural selection set out by Darwin in chapters two and three of his 1859 Origin of Species. Everyone is now familiar with the idea that the organisms that are those adapted to an environment are the “fittest” and that these are the “survivors” while those organisms that do not keep up with changes in the neighborhood are negatively selected and go extinct.
Adaptation is measured by reproductive ability. Organisms that are most adapted will survive to reproduce and will leave the largest population footprint. The “unfit” do not have to be eliminated. They simply do not survive long enough or in sufficient quantities to reproduce as effectively as those better adapted. Thus natural selection is primarily concerned with breeding. Indeed, it may not necessarily help an organism in other ways. The classic case is the peacock whose tail makes the male attractive for breeding purposes, but also makes him a target for predation.
Natural selection, therefore, is not a source of variation for it acts only on already existing species and only as a kind of gate keeper preventing the unfit from over breeding. Natural selection does not impose an optimum design on an organism; rather it rejects poor designs, abnormalities, and novelties that fall too far out of the phenotype. This disappearance of organisms is constant. Indeed, as the famous geneticist George C. Williams is supposed to have wisecracked, evolution of new species takes place despite natural selection.
According to Darwin, (and most everyone since then) whatever the cause of new species may be, their design is random and independent of the environment. And since the environment itself is in constant flux, there is no way to know which species will be selected or which will go extinct. Thus there is no direction to evolution, no arrow or ladders.
Moreover, the relationship between environment and species is not one way. Species are not passive but act on the environment that in turn acts on them. Beavers build dams, change the course of rivers, alter fish populations and so on. Herds of wild mammals graze plants to extinction, pollute water sources, and alter ecologies. And Homo sapiens industrialize. The picture of natural selection that results is of a complex and chaotic feedback loop whose ramifications are nearly always unpredictable.
Gene drift is the second negative mechanism acting against variation. Gene drift is the random decrease in the alleles of a genome and the this decrease occurs because not every allele in a population’s gene pool is passed on to the next generation. Of the incalculable number of diverse spermata and ova in the genome of a species, only a random sample will be passed on to the next generation. Because of such selective sampling, rare alleles drift out and are replaced by others. Gene drift then is measured by the rate of allele substitution.
In theory, this rate of change in an infinite population is nil, for an allele is as likely to be lost as it is to become fixed, just as flipping a coin an infinite number of times to see whether heads or tails would prevail would never produce an answer. In computer simulations of such infinite populations, the graph appears as a straight line. In evolutionary theory this is called the “Hardy-Weinberg equilibrium.
But the real world is not infinite; it is finite and stochastic; and equilibrium is affected by the size of the population. The smaller the population or number of coin flips, the greater chance that heads or tails will prevail. In gene drift, therefore, the smaller the population of sexual partners, the greater the chance an allele has to be lost to the genome. The effect of “gene drift” on smaller populations can be even more dramatic due to the so-called “founder effect” where a sexually dominant breeder establishes a harem and imprints a genetic blueprint on the isolated population.
Thus the net effect of gene drift is to decrease variation in a population as rare alleles drift out or some allele becomes fixed to the exclusion of others. This decrease in variation complicates things for it works against natural selection. The more homogenous the genome becomes, the less chance there is that a population could adapt to some change in the environment. The danger of genetic homogeneity is obvious in small populations of endangered species where variation is critical to survival.
However, at the same time that gene drift decreases genetic variation in finite populations, it increases the variation and dissimilarity between these populations and the rest of the world. If one assumes that everything had at one point a common genome, isolated parts of that genome could through gene drift become different. Eventually, gene drift could lead to speciation and the inability of different populations to interbreed.
Positive forces in Evolution
If natural selection and gene drift decrease variation, gene flow, recombination, and mutation increase variation. Gene flow occurs when an individual from another population moves into a population bringing with it alleles not already present in that population. Breeding between the new arrival and the established population would increase variation in the genome. Likewise, recombination also increases variation in the genome. Recombination results from the fact that sperm and egg cells are haploid and must combine to form a complete zygote. The near infinite number of diverse spermata that could combine with an egg and the unpredictable results of random mating all contribute to increased variation.
Finally, there is mutation which also increases variation. Mutation was discovered at the beginning of 20th century when the Dutch geneticist Hugo de Vries tried to reproduce Mendel’s hybridization results by breeding the “pangenes” of the evening primrose. Instead of the predictable Mendelian results, however, de Vries got scattered or random patterns. “Pangenes” evidently could recombine in unpredictable ways. Though it was later found that the primrose (Oenothera lamarckiana) has so flimsy a genetic structure that it is unusually susceptible to mutation, de Vries’s results were still unsettling.
Until de Vries’ experiments, the orthodox view of speciation was that it occurred through “continuous variation” or minute and steady changes in organisms. De Vries’ experiments, however, suggested instead a theory of “discontinuous variation,” the abrupt appearance of a deviant offspring that could be the first of a new species. This departure from the Mendelian formula put genetics into the realm of the probable, a box in which it still remains.
De Vrie’s work thus suggested the appearance of mutants; but investigating mutation involves a quantum leap into a whole new magnitude of difficulties. Though mutant alleles are numerous enough, the effects of mutation, other than those induced by radiation or some other artificial intervention, are sufficiently rare and mysterious, especially in diploid cells, that understanding their behavior is difficult. Mutation itself is now generally thought to be a result of a mistake in the DNA base pair sequence. Such a mistake could come from a so-called “typographical error”or the loss of or inappropriate gain of a sequence of bps.
Looking at these five mechanisms, one must see how difficult it is for speciation to occur. Natural selection pares down already existing species but does not produce new ones. Gene drift, because it reduces variation within a species, could make it unadaptable and drive it into extinction. Gene flow, the injection of new alleles from a visitor, could increase variation within a species, but with whom would the interloper breed to produce a new species? Likewise, recombination only increases variation within a species unless interspecific breeding took place (improbable) and was successful (even more improbable), and produced a fertile offspring (still more improbable). One can imagine mutation leading to new species; but to do so it would have to defy natural selection. The obvious question, therefore, is how does variation within a species lead to new species? Is the five or so billion years the earth has been around enough time for the oddities that escaped negative selection to produce all the species that have come and gone since the beginning? In short, there are plenty or ways to explain variation within a species or microevolution, but macroevolution is still puzzling.
It was Ernst Mayer, one of the founders of Neo-Darwinism, who began to weave all these mechanisms together into what is still for many the standard explanation of speciation. Since his 1942 classic, Systematics and the Origin of Species, Mayr had become the dean of evolution theory and in the 1950s, he proposed a theory to answer the questions surrounding speciation. Known as allopatric speciation, the theory built on the genetic research of Morgan, Fischer, Weismann and on the idea of gene drift. It was also rooted in Darwin’s emphasis on geographic isolation of populations, which he had noted in the Galapagos.
According to Mayr, because of gene drift, new species appear at first as tiny genetic mutations in select individuals among groups which are isolated (allopatric from the Greek for “other”) for some (geological, climatic, etc) reason from the parent population. As the larger world population becomes more and more subdivided, and breeding is confined to local partners, the various local populations, because of gene drift, gradually become genetically incompatible. Eventually, according to the theory, all the sub-populations became incapable of interbreeding and, over time, the various species branches developed. Since geography, climate, or some other barrier was constantly isolating small groups, an infinite source of speciation was evidently available. Mayr, in short, proposed a totally immanent, materialistic, and natural explanation for evolution. Macro-evolution or speciation was simply a lot of micro-evolution.
Mayr’s theory is now the most widely accepted explanation of speciation. Its acceptance depended partly on the fact that it seems to be the only way to weave the various mechanisms of evolution together and partly on the fact that Mayr’s theory remained within the Darwinian tradition of gradual speciation (phyletic gradualism) and the importance of isolation. Widely accepted as it is, however, there are many who doubt that is a complete theory and propose various supplements, codicils, and modifications. There are, also, those who reject the theory altogether.
The most stalwart opponents are creationists like the Lehigh University biochemist Michael Behe, [Darwin’s Black Box: The Biochemical Challenge to Evolution, (The Free Press, 1996)], Phillip E. Johnson, Jefferson E. Peyser Professor of Law at Berkeley, [Darwin on Trial (InterVarsity Press, 1992), Reason in the Balance, (InterVarsity Press, 1996),Defeating Darwinism by Opening Minds, (InterVaristy Press, 1997)], and the Baylor philosopher and mathematician, William Dembski, [The Design Inference: Eliminating Chance Through Small Probabilities (Cambridge UP, 1998) Intelligent Design: The Bridge Between Science and Theology (InterVarsity Press, 1999). Anyone who thinks that creationists are yahoos from the hills will be jarred by the importance of the arguments they raise. Unfortunately, I can only make brief references to creationist thought here because my aim is to explore the prevailing schools of secular thought. This should not imply, however, that many creationists do not understand biology or the naturalistic philosophy that animates it.
For the layman, Philip Johnson’s books are probably the most accessible. In addition to his scientific arguments against Darwinism, Johnson raises telling points about the ease with which we accept the scientific perspective. For those with an open mind, Johnson’s work is very troubling, pointing out how the scientific mental framework--especially the Darwinian faith--into which we have all, to use Martin Heidegger’s word, been “thrown,” blinds us not only to other explanations but to problems in the scientific method. The naturalistic perspective forces us to believe that blanks in scientific metaphysics are simply minor problems that will be filled in later on. When postmoderns and others suggested that, even in principle, the gaps could never be filled in, pragmatism, relativism, historicism, the Nietzschean abyss, Heideggerian gloom, and postmodernism set in. It may, of course, be that these anti-philosophies are salutary corrections to modern chutzpah and that Johnson, never having accepted the modern project, does not need such benefits. It could be, too that he is just whistling in the dark. But, if nothing else, it is clear that Johnson understands how thin the ice upon which so much modern secular theory skates really is.
Creationists, also, however, raise scientific arguments or at least point out problems in the accepted wisdom. To oversimplify, creationists argue first, that allopatric speciation should be evidenced in the fossil record; but, they say, the record reveals no transition species. If there are no intermediate species, then complex organisms must have been independently created ex nihilo. There may not be much or even any evidence for the independent creation of species, but the argument does make it obvious that whether one accepts allopatric speciation or not, if there were a continuous fossil record, it would be very difficult to determine when one species ended and another began unless there were sudden dramatic differences--in which case if could be argued that the species were always different since they were independently created by God.
Secondly, as Michael Behe points out, evolution is always said to go from the simple to the complex; but there are, he says, a number of cases where one encounters “irreducible complexity” for which there is no simple predecessor. If there are cases of irreducible complexity, descent from a single ancestor is out. Where then did such species come from? As we shall see below, complexity theorists have provided some astonishing answers to this argument.
Thirdly, creationists argue that design is the most logical explanation for what exists. Dembski, for example, a mathematician, distinguishes between undirected or random natural events and specific events whose occurrence are of such small probability that one must infer a designer. I cannot say I find this argument very convincing. Because something is improbable does not mean it is impossible. Life is filled with unexpected singularities many of which bear non-linear consequences.
It is easy to say that creationists have an easy time of it. They know the answer they are looking for and just shoehorn the evidence into it. If this were not also the case with so many secular theorists, one could dismiss the creationists as anachronisms. The problem is that evolutionary theory itself is still so sketchy that many questions remain; and creationists are formidable at sniffing out the lacunae that remain in modern synthetic theory. Nothing, it seems, raises the ire of the secular biologist more than having a theist discover an inconsistency, even if it is legitimate. It is, in fact, disconcerting to find out how much creationism weighs on the mind of evolutionary theorists. It is partly for this reason that creationists are rarely if ever permitted to publish in scientific journals and secular theorists occasionally evaluate each other’s work not for its contribution to biology but for how much potential comfort it might provide enemy theists.
Discussing the various points of view of creation theory or attempts like those of the Jesuit paleontologist Teilhard de Chardin to marry religion and science are beyond the scope of this essay, but their work is not easily dismissed if for no other reason than its ability to keep secularists from smug overconfidence.
The primary debates among secular biologists today seem to be between four schools of thought; reductionists, pluralists, secular theorists of constrained evolution, and theorists of complexity.
Reductionists are perhaps the most orthodox of Neo-Darwinians in the evolutionary debate. By reductionists I mean those who hold a monistic theory of evolution and believe they have cut through the complex world of microbiology to isolate the most important single factor in determining evolutionary change. John Maynard Smith, a pioneer of molecular evolution, sums up the approach: “I see myself as a reductionist...I seek simple models of the world...If I have to ignore some of the detail, too bad.” Smith may be the Strabo of reductionism, but the group has many followers. Among them are George C. Williams, an evolutionary theorist at Stoney Brook and editor of the Quarterly Review of Biology; Robert Wright, the senior editor at the New Republic and author of many scientific books and articles; the Harvard socio-biologist Edward O. Wilson; Jonathan Weiner, author of, among other things, The Beak of the Finch: A Story of Evolution in our Time; and, of course, to Richard Dawkins, claimed by many to be the most important theorist of evolution today. Though there are certainly differences among these scholars, what unites them is the conviction that the gene is the basic engine of evolution. To these scholars, neo-Darwinism is the genetic micro-evolutionary production of new species. Other factors--climate, geography and so on--are, of course, important, but genetics is the key factor.
According to contemporary evolutionary theory, the winner of the “survival of the fittest”is no longer the one Tennyson described as most “red in tooth and claw,” but the one that produces the greatest number of offspring and thus wins control of the genome. This desire to pass on one’s genes is, according to reductionist theory, implanted in all organisms.
Perhaps the most outspoken representative of this monistic view is Richard Dawkins, a former anti-war protester and supporter of Eugene McCarthy and presently the Professor of Public Understanding of Science at Oxford. Dawkins’ accessible and instructive popular writings have established genetic reductionism as the primary force in evolution not only among laymen but among many biologists as well. Dawkins eschews the interdisciplinary, metaphorical, and historical explanations of biology favored by figures like Niles Eldredge and Stephen Jay Gould. His approach is direct and analytical. Complex organisms and mechanisms, he argues, are animated by intrinsic forces that metaphor, analogy, and multidimensional explanations only mask. Indirect language leaves the door open to misunderstanding and misuse of the evidence. However complex a mechanism may be, it is still guided by a single rudder and the task of the scientist is to explain how that rudder guides the whole.
The Selfish Gene (1976)was the work that first established the gene in popular literature as the rudder of evolution. The work made Dawkins famous; for it elaborated in plain English what G. C. Williams and others had stated earlier in opaque “biologese,” namely that all genes aim at replicating themselves by the most efficient means possible, and at the expense of all competitors. Organisms themselves (humans, included) are, therefore, simply “throwaway survival machines,” used for gene propagation.
To be passed on, a gene must develop a host organism whose “armament” makes it strong enough to survive to breeding age. Developing this host requires that genes engage in an endless R&D program to maintain and update their host organisms until breeding occurs. Once that process is complete, the gene hitches a ride to the offspring and the breeding organism itself is of no further use. If the offspring contains a beneficial allele, and enough of the offspring survive to produce enough fertile offspring to establish a new gene pool or genome, then evolution of a new species occurs. Evolution, therefore, is a byproduct of this struggle to build better and better organisms--or to use Dawkins-like language, “gene delivery systems.”
Dawkins’ gradualist theory is pretty orthodox Darwinism. Evolution is a piecemeal, micro process without dramatic speciation events. Likewise, it is cumulative in the sense that deleterious traits in organisms are weeded out and beneficial traits retained. It is this retentive process that helps the organism create better and better mechanisms of DNA replication.
Dawkins has little patience with those who see a more complicated and multifaceted evolutionary engine. Most of his sarcasm, however, is reserved for those who see a higher purpose in man or who deny the inherent predatory nature of genetic warfare by raising the issue of altruism. Altruism may seem to contradict genetic predation, but according to Dawkins it always has a self-interested motive. He is especially impatient with those who subscribe to the idea of a great Designer. According to Dawkins, “religion is a virus” that has found an especially well-armed survival mechanism in gullible humanity.
It is especially in The Blind Watchmaker and Climbing Mount Improbable, that Dawkins attacks believers. The magnificence of the universe and everything in it, he argues, really has little mystery. Given enough time and the narrow constraints imposed by genetic warfare, life was, in a sense, built into the material of the primordial bang. Because the sun and the earth are at least an unfathomable 4.5 billion years old, the steps taken by genetic mutation need only have been tiny, gradual, and superficially inconsequential to produce macro-evolutionary results. Eventually, according to Dawkins, DNA would emerge from the primordial chemical soup that followed the Big Bang and then life would begin. Indeed, once DNA emerged out of the originary ooze, nothing was going to keep it from becoming more and more efficient at survival.
Thus, though Dawkins resists the idea that Homo sapiens are the “aim” of evolution and rejects snobbish phrases like “subhuman primates,” he believes that evolution is progressive. Definitions of progress that imply the superiority of brainier organisms miss the point, however. Organisms evolve differently and in the ways that suit their particular needs. And needs can come in the form of brains, speed, agility, immunity, morphological complexity and so on. In short, evolution is progressive, but progress is measured differently for each species.
Dawkins, like many biologists, sees evolution as a kind of “bush” in which all species evolve from a common ancestor and then gradually branch out into different species. It is, in this metaphor, absurd to say that one branch has progressed more than another. Each “species branch” is progressing and improving, eliminating losers one after another. This accounts for the fact that so many species--99.9%, by most calculations--have disappeared.
Being no more than a “throwaway gene machine,” one would think, might make one a bit weary; but not Dawkins. He never tires, indeed, he seems to positively thrive on iconoclastic debunking of religion and slamming seemingly altruistic acts as deviously selfish methods that in reality only advance the interests of the gene. Spreading this kind of iconoclasm about seems to truly elate Dawkins.
Dawkins explains why in his latest book, Unweaving the Rainbow, the title taken from Keats’ lament about the way Newtonian “optiks” had destroyed the beauty and mystery of the rainbow. Solving mystery, says Dawkins, is as satisfying, more satisfying really, than living in its presence. For Dawkins, it is insufferable to have people living in the cave. Everyone must be brought to see the truth. And as Professor of the Public Understanding of Science, a chair endowed by the wealthy Hungarian Microsoft executive, Charles Simonyi, it is Dawkins’ job to show people that truth.
Dawkins’ biology may be satisfactory--though there are plenty who doubt it--but his views seem a bit too satisfied for this postmodern world, a bit too assured that, as Max Born once said of physics, that everything will be known “in six months.” Those that doubt that we can and will know everything, Dawkins dismisses as “intellectual imposters” without “honest thought.” Thus, in his “What’s Wrong with the Paranormal,” he explains that there is nothing science cannot explain; for everything unknown is only unknown “yet” and “mystery” is an absurdity. Genetic warfare and the natural selection that results explain all we need to know.
According to Dawkins, even his own passion for proselytizing the gene is genetically determined. According to Dawkins, humans have developed certain attributes--big brains, perseverance, persistence, goal seeking, for example—that were once helpful in hunting deer and bear and can now be put to use writing books, seeking money, and overpopulating.
This ability to control and direct attributes, however, seems to leave room for something that is consciously rather than genetically determined. And indeed, when cornered, Dawkins, avers that though he is a socio-biologist, any one-to one determinism that implies that complex wholes like humans are merely the sum of their parts is too simple. Genes are only “powerfully predictive” of human behavior; they do not have absolute control over the organism.
Even with this concession, Dawkins’ dogmatism is still so evident that he cannot avoid unnerving those who see biology as just one factor in determining human action. Perhaps it was to allow some wiggle-room between biological determinism and free will, that Dawkins introduced the idea that humanity has to a very limited extent been able to overlay its natural biological roots with “culture.” Thus in the last chapter of The Selfish Gene, Dawkins introduced the idea of the “meme,” a unit of cultural evolution corresponding to the gene in biological information. According to Dawkins, a meme can be a catch-phrase, a tune, a mode of dress, an idea or any number of other cultural entities. Such entities are like genes in the sense that once launched they gain a life of their own and “colonize” or parasitize their human vehicles. In “Viruses of the Mind,” Dawkins gives the example of the current juvenile craze of wearing a baseball cap backwards. It is not that people are “determined” to duplicate the behavior of others and wear their caps backwards; but that they do so, he says, is evidence of the existence of memes.
And if memes play a role in mating patterns--if sexual selection is affected by advertising, music, dress, the car one drives or even by the way one wears a baseball cap--they become as biologically significant as genes. Perhaps in Homo sapiens the backwards baseball cap is an ingenious design by the male chromosomes to attract females and allow the wearers to dominate the human genome. Developing a scientific epidemiology of something as ephemeral as the meme, however, seems daunting to say the least. And this is a shame for, as the world shrinks, the activity of homogenizing memes seems to be accelerating; and it would be nice to know who to blame for this emerging uniformity.
But if genes were lightning rods in the struggle between the “biology is destiny” school and liberal theory that advocates personal responsibility, memes have their own problems. By conceding that cultural constructs can to some extent oversee reality, the idea of memes seemed to confirm what opponents of socio-biology had been saying all along.
The debate between determinists and liberals might, however, have remained a “debate” had liberal thought not itself become more radical. Soon the debate turn into the “culture war,” the struggle between the “biology as destiny” school and the New Left and postmodern thought that began, with the influence of Heidegger, Foucault, Lyotard and others, to marginalize liberal thought. For postmoderns, science was a “metanarrative” or a cultural construct created by White Victorian Males. Biological determinism as set out by E. O. Wilson had always been opposed by liberal thought, but with the hegemony of the “New Left” and “political correctness” in academia, the conflict reached a new level of radiation. Part of the problem is that most biologists and scientists do not understand the Nietzschean/Heideggerian insight that in our non-algorithmic world science is just a “point of view” and thinkers in the humanities do not understand that all reality is not a “construct.”
One example of this lies in the way that memes and genes entered the age-old debate between those who see gender roles as natural and those who see those roles as the result of nurture; or, to use the modern jargon, those who see gender as “constructed” and essentialists who see it as biological. Political correctness, of course, put socio-biology and its newest manifestation, evolutionary psychology, squarely in the cross hairs; for if biology or genetics explained behavior, one could not, as political correctness required, maintain that human nature is infinitely malleable and that genders were merely social constructs. The meme may, however, constitute a last minute reprieve; for if biology had been superceded by culture then gender roles are mere memes imposed by that culture. Erase offending memes and gender differences evaporate. “Poof!”
Certainly there can be little doubt that feminist, gay, and lesbian activists have politicized biology, but it is also true they have brought into the open political implications that were already there when biology/science was treated as divine wisdom. There is, in short, very little politically neutral or unsituated ground in biological matters.
Meme theory, however interesting from a cultural point of view departs from genetic determinism and has little support among most reductionists. Evolutionary psychologists like Richard Wright (The Moral Animal 1994; Non-Zero: The Logic of Human Destiny 2000), for example, find a genetic base for gender differences and for all human psychology and activity. Evolutionary psychology, an outgrowth of socio-biology, argues that gender differences are a natural result of different male and female physiology. Since passing on their genes is relatively simple for males, males are, in every known society, far more promiscuous, polygamous, and adventurous than females. They have, in short, glutted the market and made sperm cheap and easy to find.
It is much more complicated, on the other hand, for females to pass on their genes. Sperm may be cheap, but eggs are few, far between, and must be carefully protected before and after fertilization. A less risky life is a necessity. Moreover, since there is no problem locating sperm, polyandry and promiscuity are infrequent among females. Indeed, for females, sexual active males are important only at the outset. The challenge is to keep them around afterwards for protection and opening jars.
It may have been Dawkins who first suggested the idea of memes, but it is Daniel C. Dennett who most developed it. Dennett is the Director of the Center for Cognitive Studies at Tufts and author of some ambitious works [The Intentional Stance, (1987); Consciousness Explained (1991)]; and recently, Darwin’s Dangerous Idea: Evolution and the Meaning of Life (1995). There is a similarity between Dennett and Dawkins that goes beyond their friendship. Like Dawkins, Dennett is a daunting thinker who sees in Darwinian thought a universal answer to questions that have plagued humanity from the beginning of thought; and like Dawkins, Dennett seems convinced that postmodern skepticism about the abilities of human reason is vastly overblown.
For Dennett, “natural selection” is a “universal acid,” an allusion to the child’s notion of an acid so powerful that it burns through everything--the beaker, the laboratory table, the floor, the building, the ground, the entire earth, and whatever else gets in its way. According to Dennett, the problem with natural selection is that the idea has been fire-walled inside biology. Dennett’s argument is that natural selection is “substrate neutral,” that is, it is a universal process that not only explains mutation but the development and progress of culture, politics, morality and everything else. If the corrosive power of natural selection were to be applied to society, politics, economics, the arts, morality, and everything else, it would explain the way improved varieties and species of all of these entities have emerged.
The power of explanation by natural selection, according to Dennett, has been stymied by what he dismisses as “skyhooks.” Skyhooks are natural laws, universals, and other pie-in-the-sky notions (Chomsky’s universal grammar particularly bothers him) dragged in to protect the idea of order or design in the universe. If such skyhooks are abandoned, it would be evident that outmoded and unfit elements are eliminated from our world by natural selection.
But, if I understand it correctly, Dennett’s universal acid provides the same kind of Superman rescue he condemns in religion, teleology, natural law and so on. Every universal, every Grund, he claims, is dissolved by natural selection--except his idea of progress through natural selection, a Grund that supports everything and leads to ever greater levels of perfection. And if he did not have faith in that acid as the engine of progress, Dennett would also be a postmodern philosopher plagued with doubt as everything dissolved--including his acid.
With natural selection spared, however, Dennett can bring order and design back, not from above or beyond, but from the ground up according to the “natural” engineering that he believes lies within the evolutionary process itself. If engineering is building things, then by a process Dennett calls “reverse engineering,” biologists can or should ask “why has natural selection built this organism this way?” Answering that question answers the only question that matters, the question that fascinated Leibnitz, Nietzsche, Heidegger, and many others: why is there something rather than nothing. The answer may, however, be chance, an answer that Nietzsche--but not Dennett--might like.
Several questions occur to me in reductionist genetics. The first is that the idea of “reverse engineering” seems to imply that the engine of evolution lies in an organism’s ability to “choose” better and better modes of gene replication. But how can one know that the 99.9% of all known species that are now extinct were less efficient reproducers and not simply unlucky? Most evolution at the molecular level is simply the result of genetic drift, the chance replacement of one gene with another slightly different but functionally equivalent gene. Why assume that such changes are anything other than the result of errors in DNA replication? The question of why a species’ “engineers” things in a certain way seems to be like asking why a million typing monkey eventually produce whatever they produce. Even if they finally do reproduce Shakespeare’s works, no one would wonder “why” they typed his works instead of Tolstoy’s. In other words, if environment selects survivors and environmental change is random and unpredictable, why suppose that later species are any more adapted than earlier ones? Is the environment progressing too? Why not simply suppose that chance dictates which organisms emerge, which environment they will encounter, and who or what survives?
Secondly, the assumption that everything is designed by natural selection, makes evolutionary biologists into creative writers whose purpose is to figure out what nature had in mind. In fact, all we know is what there is and very little about why it is. As Orr put it--in his italics--”evolutionary biologists thrive on creating adaptive stories where Design is least obvious. After all, where is the glory in explaining why some new species of mite is brown (‘it hides in dirt’)? The great challenge is to explain why some feature--whose Design is far from apparent--is actually adaptive and optimally Designed (‘this enzyme is more common in mother than the fetus because...’).” It is problems like this that put Dennett at odds with biologists who argue that aature’s designs are simply the blind product of the shuffling of the genetic dice.
For Dennett, however, questioning whether there is purpose in natural selection is smoking-gun-evidence that one is a closet anti-Darwinian, maybe even a theist (a believer in “skyhooks”), rather than one who is raising legitimate questions about what we can know. To imply that human knowledge is limited, however, need not derive from a belief in original sin--however salutary that may be--or that one is a believer in divine purpose. It merely implies that the world is a pretty complicated and multidimensional place, a place too complicated for the certainties of algorithmic reason and the logos. It might be better, in other words, to treat nature as a force with a life of its own with which we can have a “conversation” but never completely know and master. Whatever one may feel about the excesses of postmodern thought, the weaknesses of the modern project and the notion of the omniscient and objective observer have all been glaringly pointed out by Foucault, Derrida, Heidegger, chaos theory, Prigogine and others.
Darwin’s Dangerous Idea, however, is not only a book about genes and extending the universal acid of natural selection to all human and social phenomena, but about explaining memes and their role in reproduction. As Dawkins noted, memes may well play a role in sexual selection, but there are also a lot of reasons to think that memes and genes are pretty dissimilar. In the first place, isolated memes--fads, ideas, etc--cannot reproduce and in any case few (as Dawkins points out) would say that ideas just because they stick around a long time or have lots of offspring are any more fit than those that do not. The flat earth advocates or Platygaeanists, after all, have a website and UFO and Elvis sightings are pretty common.
Most importantly, memes differ from genes because as memes spread they tend to produce homogenization throughout the population (blue jeans, the ubiquitous book packs of young travelers, new age air-head “philosophy,” popular “music”) whereas genes, precisely because they are genes, never blend. If they did natural selection would cease. Despite the fact that genes do not tend toward homogeneity, Dennett, like Dawkins, implies that memes have superceded genes as the primary force in natural selection. This seems to suggest that individual physiology or intellectual factors are less important in sexual selection in Homo sapiens than is conformity to the current culture of the herd. It is a fearsome thought.
However much Dennett empowers the meme and its ability to bind humans into a single tribe, when it comes to morality, he reverts back to genetics and his understanding of the genetic arrow in evolutionary theory. Far from emphasizing the eternal diversity that Mendelian genetics indicated, however, Dennett develops a kind of new age genetics that argues--to summarize--that because mothers nurse their young, siblings care for each other, and family and kinship relationships are stronger than relations between passengers on a bus, we are headed, as the globe shrinks, toward a huge family with a universal morality. All of this, he argues, is genetically based and programmed. One might make a genetic argument about gender differences, even about nursing mothers, and maybe about sibling behavior, but seeing the emergence of a global morality as genetically rather than culturally based seems a bit of a reach, to say nothing about its Brave New World dimensions.
A lot of Dennett’s ideas about memes and global morality are similar to those of the evolutionary psychologist Robert Wright. Most figures in evolutionary psychology tilt toward nature rather than nurture, that is, to use Dennett’s language, they make genes more important than memes. Wright takes this idea even farther arguing that there was from the beginning a kind of genetic “destiny” in evolution that leads toward more and more complex and tightly knit organic and social organisms and organizations. It may be that social evolution is moving toward some kind of modern nightmare of tightly knit complexity, the McWorld of Benjamin Barber, but that this has anything to do with genetics seems suspicious to me.
For Dawkins and Dennett, and for that matter for Wright, the arrow of evolution seems to be straight forward. Everything has a purpose or a destiny. Genes and finally memes are the central focus of change and these forces seem to be converging toward a world-wide human ant farm or, as they say today, a “global village.”
PLURALISTS: By pluralists I mean figures like Stephen Jay Gould, Niles Eldredge, and Richard Lewontin. Pluralists dispute the idea that natural selection at the genetic level or at any other level supplies a complete explanation of evolution. They suggest other “things” are at work here and whatever they are--extrinsic elements like geological forces, climatic changes, collisions with asteroids-- they have made evolution a random and aimless affair. It may have produced man but could just as well have produced whistling sunflowers: no destination, no arrow of time, no point at all. Pluralists are, therefore, fond of emphasizing the large roles played by contingency and by the often accidental non-adaptive and even deleterious consequences that occur in some areas of an organism’s physiology when its overall morphology does adapt.
The conflict between reductionists like Dawkins on the one hand and Gould, Eldredge, and Lewontin on the other is probably the major battle in evolutionary theory today. The beginning of the conflict dates back a quarter of a century when Gould began to have doubts about whether gradualist microevolution, the very foundation of neo-Darwinism, was a sufficient explanation for the huge number of species that have existed since life began.
According to the traditional view, species were in a constant state of evolution with microscopic changes occurring at an even rate for the entire taxa and over the entire geographic range of the species. The microscopic changes were a response to an environment that was itself constantly evolving and to which species had to constantly adapt. Species, in other words, were, like marbles rolling over the ground, in a state of constant adaptation to the environment. It followed that somewhere there was a fossilized record of these gradual changes and that any gap in that record was simply a result of incomplete research that could at least in theory, be completed.
In 1972, Gould and Niles Eldredge introduced the idea of punctuated equilibrium, usually abbreviated as PE or, by its detractors, as “Punk Eek.” Punctuated equilibrium presented a revolutionary contrast to the traditional view of “phyletic gradualistm.” What made PE exceptional was first that it suggested that the fossil record did not indicate a norm of gradual change. In fact, rather than change, the fossils indicated eons during which no morphological change occurred at all. Normality was not change but stasis.
Secondly, Gould and Eldredge suggested that these periods of stasis were suddenly “punctuated” by rapid speciation events produced by unpredictable mutations. Most mutations were neutral, occurring constantly without producing evident morphological changes. Then for some reason, a mutation produced really dramatic changes. The gaps in the fossil record, in other words, did not indicate “missing links” but the parenthesis between rapid speciation events. Moreover, said Gould and Eldredge, whatever fossil record did exist was unlikely to ever be filled in, for it was subject to asteroids, earthquakes, geological, and climatic changes.
Thirdly, Gould and Eldrege suggested that if morphological change was the result of a genetic mutation suddenly taking hold, then such a change could occur, in fact, was likely to occur in allopatric populations, but could also occur in sympatric populations. Rapid genetic mutation could occur anywhere at any time in large or small populations. All populations, even allopatric populations, remain in a period of stasis for millions of years despite their geographic isolation and even during extreme geological and climatic changes. Then, for very contingent reasons, speciation occurs. The idea that the fossil record was subject to chance, that eons could pass without morphological change, and that unpredictable mutations suddenly caused rapid speciation among allopatric and sympatric populations cast the whole notion of Darwinian gradualism into controversy. This opening of the door to chance, the enemy of all those who, like Dawkins believe everything can be known, was the great threat presented by punctuated equilibrium.
Along with punctuated equilibrium, Gould, Lewontin, and Eldredge are most famous for their strong endorsement of the aimlessness and deep contingency of evolution and of the consequent impossibility of seeing any direction in it. Richard Lewontin’s argument is illustrative. Lewontin’s hostility to reductionist genetics is well known and is pretty accessible in his cleverly entitled The Triple Helix: Gene, Organism, and Environment and It Ain’t Necessarily So: The Dream of the Human Genome and Other Illusions, both strong attacks on the notion that DNA represents the equivalent of the Holy Grail in evolution and biology.
For Lewontin, there are multiple forces at work and it is simplistic to think that one can hold all these constant and just examine the genome. The complex and unpredictable way that gene, organism, and environment all interact and feed back into each other means that evolution could never be understood through mere genetics. Indeed, reason itself might not be able to grasp such contingencies because reason is limited to cause and effect processes that can be duplicated. According to Lewontin, cracking of the double helix can tell us a great deal about human disease, but genes are not mere blueprints for the organism. Knowing the nucleotide sequence of DNA does not tell us about the other parts of the cell, about the interaction of the genes with those other parts or with other cells. The view that DNA is the key to everything is a relic of modernity, a product of the view that the whole can be understood by taking it apart and putting it back together again. Instead, the organism, its neighboring species, and the environment are never constant but an ever evolving complex of “co-creation.”
Co-creation challenges any concept of “reverse engineering.” By putting contingency at center stage, it emphasizes not engineering but the miraculous. So many tiny and seemingly insignificant events had to occur to produce the present catalogue of critters that these conditions could never be occur again. The interrelatedness of species, the possibilities for variation, convertibility, and odd mutation, all facilitated by the crowding of the genetic material of all organisms into a tiny area of the DNA sequence, make it clear that any rerunning the evolutionary tape would produce a whole new symphony. There can be no “play it again, Sam” in this scenario. In Wonderful Life (1989) and Full House (1996), Gould argues that man is simply an accident, “a detail, not a purpose;” a “wildly improbable evolutionary event.”
Gould’s argument is illustrated in his reading of the Burgess Shale in British Colombia’s Yoho National Park in the Canadian Rockies. This gold mine of Cambrian (550 million years ago) fossils was discovered in 1909 by Charles D. Walcott and is famous as a fossil storehouse of quite unique and bizarre organisms (the five-eyed Opabinia whose elephant-trunk has a giant claw at the end; the Anomalocaris, an arthropod-like predator; the Dinomischus, an animal that looks like a flower; and a host of other Cambrian flora and fauna) that went extinct even though they were well adapted, even better adapted than those that survived.
According to Gould, when Walcott discovered this mother-lode of fossils, he did not recognize their uniqueness and “shoehorned” them into early predecessors of contemporary phyla because that was the only thing that made sense in orthodox phyletic gradualism. In fact, again according to Gould, the Cambrian fossils were those of species that were wiped out by freakish events. And, more sobering, it could well have been our ancestors that went extinct rather than these weird creatures. In short, what occurs is not survival of the fittest, but survival of the luckiest, a prospect that takes all direction and purpose out of evolution. Indeed, it implies not only that if the evolutionary tape were run again, it would not produce man, but it makes one wonder how many times it has already been run.
One of the most famous illustrations of the central role of contingency in evolution was suggested by Gould and Lewontin when they pointed out that not all aspects of a species physiology revealed adaptation. In fact, evolution seems, according to Gould and Lewontin, to have produced a lot of so-called “spandrels,” physiological accidents that serve no useful purpose to an organism and have no adaptive function. They were simply the accidental byproduct of some other mutation that might have served a useful purpose. Reverse engineering, in other words, was pointless because so many elements in the morphology of species were pointless.
To illustrate the point, in 1979 Gould and Lewontin presented to the Royal Society of London a now famous paper entitled “The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme.” The paper was an attempt to dislodge the prevailing orthodoxy which gave “near omnipotence [to] natural selection in forging organic design and fashioning the best among possible worlds.” Using examples from architecture and anthropology, the authors ridiculed evolutionary biology’s belief that every part of an organism was perfectly designed just as Voltaire’s Pangloss had argued “things cannot be other than they are...Everything is made for the best purpose. Our noses were made to carry spectacles, so we have spectacles. Legs were clearly intended for breeches, and we wear them.”
Gould is fond of drawing examples from literature, history, and other disciplines to illustrate biological points, a habit that distinguishes him from Dawkins. Here he and Lewontin elided Pangloss’ vision of the world to the interior architecture of the cathedral in Venice. The authors discussed the way roughly triangular surfaces with great decorative potential had emerged at the top of the columns at San Marco when the architects erected the large dome-shaped roof. Since such a large dome would have looked absurd if it were just set atop the four columns like a lid on four sticks, the architects widened the top of the columns by flaring them out to the right and left and then erecting the roof-dome on the widened tops. Two roughly triangular surfaces or spandrels resulted at the widened tops of each of the four columns.
No one thought of in advance of creating a “spandrel.” It was the accidental byproduct--a ”secondary epiphenomenon”--of erecting the dome. Yet the spandrels became the surfaces on which appeared the imposing mosaics of the four evangelists and below them, the Biblical rivers, Tigris, Euphrates, Indus, and Nile. A Panglossian reading of the spandrels would conclude not that they were serendipitous but that they had been part of the best of all possible designs, created precisely for the evangelists. “Spandrels,” however, argued Gould and Lewontin, “do not exist to house the evangelists.” And like cathedrals, “organisms” must be seen as “integrated entities, not collections of discrete objects” all of which were designed to fit the whole.
The pluralist position has multiple ramifications beyond challenging biological monism. This should not be too surprising since to talk about evolution is already to talk about both things your mother told you should never be discussed at dinner: religion and politics. In the political realm, Lewontin’s and Gould’s argument that the products of evolution are a random, chaotic complex of genetics and environment is grist for the mill of the politically correct position that human nature is constructed while others argue that Gould’s endorsement of contingency veers so closely to the miraculous that he aids creationism.
A still more intriguing issue that critics sometimes raise against Gould and Lewontin is the possibility that their biology is subordinate to their socialist-leftist politics, the anthropology of Franz Boas, and to the agenda of fellow travelers like Margaret Mead, Ruth Benedict, and Ashley Montague. At base, lest anyone think debates in science are different than those in other fields, the conflict is over whether individuals and their history are a product of biological determinism, nature, and science on the one hand or culture, nurture, and environment on the other.
The debate is not new. Recall that in the 19th century, many religious leaders who did not reject Darwin’s 1859 Origin of Species outright, incorporated it into their religion arguing that evolution was God’s plan for creation, his method of creating man. Never mind that it took several billion years before God got around to that main event, what evolution implied to these “progressive,” religious evolutionists was that if “survival of the fittest” was God’s ideal, then by God “social Darwinism” was God’s work in action. The exploitation of the weaker classes, races, and peoples was simply doing God’s work.
Horrified at the use of Darwinian science to justify such an interpretation of the survival of the fittest, Gould and Lewontin, so their critics allege, created punctuated equilibrium, an evolution complete with periodic bursts of revolutionary upheaval from below and with environment trumping genetics. PE, in other words, was not biology, but a way to advance the agenda of environmental determinism, cultural relativism, and to instill Marxism into academia, culture, and science.
Certainly Gould’s and Lewontin’s politics seem to intrude constantly and unnecessarily in their writings. And certainly one can see a parallel between Marxism and punctuated equilibrium. Gould has never denied his left wing biases or his participation in leftist organizations like Science for the People at Cambridge. But even if Gould and Lewontin got their biological theory from their political theory--or from the air or eating their vegetables--this does not mean the ideas are wrong. Planck supposedly got his idea of quanta from a dream about tiny insects. Biological assertions require biological refutations. In any case, their argument that, since contingency is everywhere, humans can only make modest claims about evolution and history is not exactly the most obvious characteristic of Marxism. In summary, what stands out in the arguments of pluralists is their willingness to acknowledge how little we know and how large a role contingency plays in everything.
Many of Gould’s detractors also argue that he is tilting at windmills, that no one believes in teleological evolution anyway and that all acknowledge the contingency of evolution. I have no idea about the proportion of believers, atheists, and agnostics on this question, but it certainly seems that the common metaphor of evolutionary theorists is that of the ladder.
Secular Theorists of Constrained Evolution
By constrained evolution, I mean a teleological or directed evolution, the view that an intelligent species was somehow built into the things from the beginning. Theorists of constrained evolution like Robert Wright, Simon Conway Morris at Cambridge, and, Denton argue--against Gould, Lewontin, and Eldredge--that evolution of intelligent life is not the result of a freakish coincidence. Asteroids do strike but on the whole the laws of nature constrain chance and provide, if not a design, at least an arrow to the evolutionary process. This “arrow” guides evolution from the simple to the complex, from a (relatively) simple bacterium to Homo sapiens or at least to some form of intelligent life.
If the pluralists are wrong to incorporate so much contingency, say the theorists of constraint, so too, are the reductionists like Dawkins wrong to promote simplistic arguments like the primacy of the gene. S. Conway Morris, a biologist (with a political message as well) provides an interesting introduction to this school of thought. Lamenting the relativistic fallout of Sausurre’s separation of res and verba and Derrida’s “poisonous ideas,” Morris aims at a middle ground between postmodern relativism and Gould’s contingency on the one hand and Dawkin’s simplistic reductionism on the other.
Morris certainly makes a good case for dismissing Dawkins on the grounds that recent research has shown that different morphologies and behaviors do not have a genetic cause. Indeed, so much genetic information is shared by all living creatures that we must conclude that the gene is only part of the mechanism of evolution, morphology, and behavior. Morris’ criticism of Gould, however, seems less convincing, based on the idea--the faith--that Gould’s emphasis on extinct organisms and evolutionary cul de sacs is too one-sided. Such evolutionary dead ends were, according to Morris, really only stumbling blocks in a wider, progressive evolutionary process. In other words, where one organism fails to overcome a roadblock, another organism eventually succeeds. Gould, argues Morris, concentrates on the fate of particular organisms rather than on the process as a whole. If one looks at the whole process through the eons of time, says Morris, one finds that apparent roadblocks are really “convergences” along the evolutionary process, necessary junctions or crossroads through which organisms must pass in order to progress. Bursting through the convergences makes the arrow of evolution possible, or better, necessary.
This seems to me to be a metaphysical rather than a biological argument. It stems from Morris’ conviction that postmodernism is just a fad that could--or should--be overcome if we only jumped outside the context and took a more objective point of view. But how does one jump out of a context that began with the Big Bang and still surrounds us? How can we know where it is going?
The essence of constrained theory is that the laws of physics, chemistry and biology impose a certain behavior on inorganic and only to a slightly lesser extent, organic material. This means that there are only certain permissible paths that matter can take as it evolves from the inorganic to organic. Evolution in this view is never reversed. It is always from the simple to the complex whether one is talking about the formation of basic elements or about organic material.
Stellar nuclear fusion begins--and must begin--by synthesizing complex elements of the universe out of the simplest atomic building blocks: Hydrogen, the lightest and most common element (90% of all atoms) is heated in the stellar furnace until it becomes helium (four hydrogen atoms); helium, the second lightest element is then heated at extraordinary temperatures until it becomes carbon, (three helium nuclei or alpha particles), and then carbon is heated into oxygen and so on. Lighter elements always precede heavier ones so that there is a natural progression from hydrogen to carbon, the element that predominates in living organisms, the very basis of life. These elements, because they are the lightest and regularly share electrons to form strong double and triple bonds with each other, are the basic building blocks of the natural world.
Likewise, in organic evolution, the simplest organisms at the beginning are, it is said, transformed into later complex organisms. In short, the laws of physics and chemistry operating on the basic components constrain the course of development and “force” them toward complexity. And since thinking creatures are the most complex organisms we know, the simple-to-complex arrow made rational organisms of some sort very likely if not inevitable.
Though one can understand that stellar fusion proceeds from lighter simpler elements to heavier complex ones, I wonder why the same logic applies to much more complex organic procedures. In chaos theory complicated things go not only go from the simple to the complex, but from the complex to the simple.
Moreover, far from indicating the reassuring view that rational complex life was built into things from the beginning, this secularized version of the design argument seems to me to give one a disconcerting sense of just how delicate, precarious, and unlikely the whole process was. The universe had to have a certain size/age before life producing elements could evolve; the gravitational constant had to be just as it was for galaxies and stars to form; the stars had to live long enough and get hot enough to produce the basic elements; hydrogen, oxygen, nitrogen, and carbon had then to be shielded from the high energy ultraviolet waves that earlier had produced them; the planets had to be in certain orbits with respect to the sun; molecules had to remain stable once formed, and so on. To believe that these and the many other things that made the universe the way it is had evolve in this fashion rather than being a random result, seems an act of extraordinary faith. In short, the fact that everything is so tightly organized and interdependent, far from eliminating chance, seems to reenforce one’s suspicion that one tiny unexpected jolt could at any time have thrown the whole business into a tailspin--and still could. Such a jarring thought makes one understand why a Designer is so often invoked.
An arresting description of just how dicey the circumstances under which life is permitted in the cosmos is in John D. Barrow and Frank J. Tipler, The Anthropic Principle. The anthropic principle is the principle that demonstrates the way everything in the universe is integrated to support human life. Tipler and Barrow particularly emphasize the crucial importance of carbon as the foundation of organic life. They make no appeal to a Designer, however. In fact, everything for them seems to result from chance and coincidence.
One of the most fascinating cases of believers in constrained evolutionary theory is that of Robert Wright, the author of The Moral Animal: Evolutionary Psychology and Everyday Life (1994) and Nonzero: The Logic of Human Destiny (2000). Wright believes that there is an arrow leading from “the primordial ooze to the world wide web” and thinks that Gould has overemphasized the flukier dimensions of evolution. This is particulary disturbing, says Wright (and others) because by hammering home the miraculous appearance of humans, Gould plays into the hands of creationists who also doubt that evolution could have produced human beings.
Non-zero is divided into two parts, “life” and “evolution.” Wright’s thesis in Non-Zero, at least in the first part (which is well over half the book), is not so much biological as sociological. To him human progress, ever and ever higher levels of it, is built into history. This progressive element stem from the fact that humans are naturally acquisitive and acquisition requires cooperation; and cooperation testifies to progress. For Wright, it is cooperation that leads to the agricultural revolution, the industrial revolution, and the information revolution. Each revolution leads to an increasingly complex and integrated society. Greater population density leads to--or it better lead to--greater levels of innovation. It is a non-zero game in which everyone wins and, as the world shrinks, no one will be left out of the game. Everything, it seems, work to this good end: overpopulation and even war are not, in the non-zero sum world, unmixed blessings for they too, require greater cooperation.
Whether this rush to complexity and ever greater levels of integration is progress and not nightmare is certainly open to question. Many social theorists are not so sanguine about where things are going while still others challenge the orthodox conviction that the world is headed toward globalization and integration. For example, David Reynolds argues that there is a dialectical process of integration and division going on in the world. For every NAFTA, there are the counterexamples of the former Yugoslavia, the Muslin/Hindu time bomb in the Asian subcontinent, and so on. In any case, it is not only that Wright ignores disintegration in favor of integration or that he ignores the fact that bad things like wars fuel the drive to integration that troubles me. It is rather that he does not see any darker side in the whole beehive he envisions at the end.
In the last third of Non-Zero, Wright argues that there is a parallel between human evolution (progress in civilization) and biological evolution because biological evolution also evinces ever greater levels of complexity. According to Wright, biological evolution leads to diversity. The bacterium naturally becomes more and more complicated and this increasing complexity eventually leads to new organisms and eventually to organisms with large brains. And large brained organisms survive best because they are better able to acquire things than simpler organisms. And once acquisition takes place, progress begins.
I don’t know if Wright’s arrow of evolution is better biology than Gould’s biology of roulette. It is certainly true that “life starts simple and gets more complicated.” Even the bacterium and the virus, as we unfortunately well know, seem to respond to danger and become more complicated. But I have a hard time seeing increasing complexity as anything but increasing complexity. Besides, if a simple bacterium, mysterious as it may be, is going to change at all, it obviously has a lot more possibilities for becoming more complicated than it does of becoming simpler.
If Wright’s work is optimistic about the way evolution must go, it is nothing compared to Michael Denton’s Nature’s Destiny: How the Laws of Biology reveal Purpose in the Universe. Denton is a fascinating case. In 1986, he wrote Evolution: A Theory in Crisis, a harsh criticism of the whole idea that evolution could answer the “enigma of life’s origin.” I have to say, I preferred that first book over the second, not because I doubt evolution or think that Denton had discovered a crisis, but because he raised a number of questions that biologists just don’t like to talk about.
Not the least of the questions raised in A Theory in Crisis appears in chapter eleven, entitled “The mystery of life’s origin.” Here Denton points out the fact that since science deals with repeatable phenomena--events that can be observed and tested again and again, occasionally even reproduced in the laboratory--and since as far as we know life exists only here on earth, there is no way to make scientific hypotheses about its origins. Such an endeavor would require many empirical observations of the spontaneous generation of the kind of life that exists here. Even the laboratory creation of organic material from inorganic could not prove that it was this route that led to life on earth. In short, to know, to know how this our order came about will probably always remain in the realm of the probable.
Indeed, as science moves more and more into issues like spontaneity, randomness, and chaos theory, it is finding that, at least at this level of inquiry, one is not doing traditional science but having a conversation with enigmatic nature. Sometimes nature responds openly, sometimes in an enigmatic way, and sometimes not at all. Hard evolutionists do not like to talk about such things because they think it fuels the fire of creationism. It may; but it is also true that a “science” of a “singularity” is a contradiction in terms.
A second question Theory in Crisis raised was the difficulty of distinguishing between “micro” and “macro” evolution. According to Denton, intermediate species did not exist and Darwin had extended an acceptable and rather trivial “micro” evolutionary theory of limited change (the most famous being the way the biston betularia moth changed its color from light to dark as the environment changed from rural to sooty industrial) into the “macro” world of speciation where the theory was unwarranted. Not all biologists, of course, agree on the distinction. Some argue that macro is just a lot of micro and others see the mechanism of speciation as quite different than that of microscopic change. Still, it is interesting to speculate how one could ever determine when a supposedly continuous process of microscopic change can be said to have generated a new species and when it resumed its journey, stopped again, spit out another species, and so on. Discussing “transition” species is, obviously, not something that can always be done with precision or proven and always runs the same danger of creative writing that Orr complained about in the realm of adaptation.
Denton, of course, willingly or not, helped creationists argue that micro evolution around a basic “type” or structure is all the evidence ever warranted and that to extend the theory into speciation, as Darwin did, was to take a “partial truth” too far. For the layman, it is probably best to leave the matter of how micro becomes macro open.
Denton’s new book, Nature’s Destiny, is quite different. In this text, Denton accepts evolution. Indeed, he has become one of the greatest champions of constrained evolution. His claim, as the title implies, is that the evolution of human life is a natural process of self-organization that can be completely understood by human reason and is, therefore, a thorough refutation of creationist claims that special intervention was necessary. In short, far from being impossible, evolution was inevitable, comprehensible, and rational..
To claim that evolution is natural is not so novel; but to claim that it is completely accessible to reason and to do so after the postmodern or Heideggerian fallout seems positively daredevil. According to Denton, the origin of human life must be “viewed as something quite inevitable and built into the laws of nature from the beginning,” What convinces Denton of this view is the fact that the thermal properties of water, the make-up of cells, the characteristics of carbon and all the elements of life synthesized in the interior of stars seem designed to sustain life in a certain way. The hub of the argument, however, it seems, is the DNA evidence.”One of the most surprising discoveries that has arisen in DNA sequencing,” he writes, “has been the remarkable finding that the genomes of all organisms are clustered together in a tiny region of DNA sequence space forming a tree of related sequences that can all be interconverted via a series of tiny incremental steps....The distance between man and chimp which seems so significant and obvious at a gross morphological level is trivial in DNA space.”
In other words, it is the infinitesimal size of the DNA space that living organisms share that makes mutation possible and constitutes the case for the genesis from a single species. That is, of course, the heart of evolutionary theory. But Denton seems to me to take the argument too far, asserting that the DNA alphabet that produced the present catalogue of species was itself inevitable. It is true that in the double helix structure that characterizes DNA, the four base pairs always follow the same patter: cytosine always pairs with guanine and adenine with thymidine. But does the nucleotide alphabet have to be the way is? Why couldn’t the letters be arranged differently? To say that the sequence is what it is or we wouldn’t be here seems to be a tautological teleology that proves that if DNA did not do its job Watson and Crick wouldn’t have been around to discover the double helix. But the fact that we are here seems to me to prove only we are here not that this is the only way things could be.
There is, in other words, something too comfortable about Denton’s claim; for like most theorists of constraint, it implies an elimination of the random and chaotic but does not seem to give evidence for that elimination. Instead, what Denton provides is a kind of Aristotelian argument that the universe has a purpose or teleological end. It may: but this argument for it is unconvincing.
Denton’s new theory may not be religion, it may not even be metaphysics, but it is something like the design principle. He argues that “the basic thesis of this book is that the cosmos is uniquely fit for human existence.” This is probably true, but it does not explain why the universe is not simply the result of some cosmic roulette game. How many times has this game been played with different results or with results that established some other form of life? Why anyway, in a cosmos supposedly designed for human life are there so many dangerous things out there like zooming asteroids, lethal cosmic radiation, and wily retroviruses. Why is there so much wasted or pointless energy? Why does the sun radiate in all directions? It would be ever so much more economical if sunlight just followed us around. How many empty galaxy mistakes are there out there in this anthropic cosmos anyway?
Moreover, relying on DNA sequencing doesn’t seem to me to be the most persuasive case for a definitive theory. Taxonomy has changed its measuring stick so many times and forced species to jump from one hoop to another so many times that I have to doubt that the new DNA measure will be anymore definitive than say cell structure or plain morphology was before. If Homo sapiens is 97% the same as the chimp when we look at the DNA sequences, it seems to me to indicate either that there is a lot more to making Homo sapiens than DNA or that this 3% must pack one hell of a wallop. My suspicion is that DNA is not the ultimate building block, but just one of a series of Chinese biological boxes which hold deeper mysteries inside.
A theory somewhat related to the constrained theory just describe is
Though self-organization theory or complexity theory as it is also called deals with evolution, it is primarily concerned with the origin of life from inorganic matter. It is similar to constrained theory in its belief that some kind of intelligent life was to be expected. However, where constrained theory focus on the logical progression of things, self-organization theory emphasizes randomness and contingency. Complexity theory grew up in biology out of the study of non-linear dynamics in mathematics, physics, and chemistry and builds on the ideas of autocatalysis developed by Manfred Eigen and Ilya Prigogine.
Pluralist biologists like Gould, Eldredge, and Lewontin, as we have seen, emphasize extrinsic causes of evolution. Organisms are said to live in a constantly changing universe to which species must constantly respond. Complexity theorists, on the other hand, begin evolution with the intrinsic forces operating within an organism. Climatic and geological forces are important, but secondary. An organism must first be born, have a viable structure, survive the challenges of its local environment, and so on before it encounters the larger forces.
One aspect of this emphasis on the intrinsic is the study of the way that organization can arise from primordial disorganization. One might think of the way that ancient Greek or Christian myths explored the way a deity brought order out of chaos--except that in this case there is no deity. The process is entirely rational with chaos giving way to order through random autocatalysis. The idea is relatively new and attracted attention in 1967 when Manfred Eigen won the Nobel Prize in chemistry for his work on autocatalytic set theory and again in 1977 when Ilya Prigogine won the same prize for his study of non-linear dynamics in dissipative systems.
What makes self-organization out of disorder surprising is that, at least in conventional physics, such a thing is very unlikely. According to the second law of thermodynamics, things run downhill, not up. There is some question about whether the second law is a law or just a statistical probability, but certainly entropy is the norm. Disorder does not normally decrease but gets worse. Systems, bodies, engines, and so on do not get more efficient with time. There is no known explanation for the spontaneous appearance of order out of disorder, let alone for the appearance of increasingly complex versions of order. Someone compared the sudden appearance of order from disorder to a tornado blasting through a landfill and assembling a Mercedes-Benz. It is for this reason that theorists hypothesize the existence of hidden “strange attractors.”
An attractor is a point in space. An easy metaphor for an ordinary attractor is the way a magnet or the solar system controls the behavior of metal filings or planets. More complex examples occur in dissipative systems where energy is lost causing new patterns to constantly emerge in space. For example, a dissipative attractor would be the point in the bottom of a hemispherical bowl that attracts a marble spinning around the side; or the point that attracts a swinging pendulum into eventual submission at six o’clock.
A “strange attractor” is different because it is not a fixed point and does not produce stability. Rather, it moves in a fractal pattern with infinite variation but always in a fixed space. This produces patterns like the variety in snowflakes. No one knows how many such attractors there might be, but one could suppose that a strange attractor accounts for the ever varying formations of groups of birds, schools of fish, traffic patterns, the rivulets of a waterfall, the fluttering of a leaf, or the weather. It is thought that biological systems of self-organization might be attracted to several attractors so that the organism changes or iterates through time.
A related dimension of self-organization of chemical systems is the principle of auto-catalysis where a random soup of chemicals, without any external stimulus, spontaneously interacts to generate a new chemical which then interacts with the preceding system to produce still other interacting chemicals or systems. The result is, or can be, a cascade of spontaneous and utterly unpredictable “births” of new evolving agents or organisms. The end result of this autocatalytic process may be unpredictable, but it is nonetheless rational and the result of comprehensible laws of nature--but only in retrospect. The process does not, in other words, lend itself to algorithmic reduction. For many in self-organization theory, the primary causal agent for change in the organism is an internal attractor. Natural selection (another attractor?) plays a secondary or complementary role.
When one thinks about the complex interaction of proteins, enzymes, amino acids, peptides and so on in a living organism as self-organizing systems dancing to their own rhythm while interacting with the evolving environment, scientific “prediction” goes out the window. This is pretty dramatic stuff and not the kind of things--disorder leading to order, randomness, unpredictability, self-generation--that hard evolutionists want to talk about. It means mystery has reappeared and science was supposed to end all that.
The miraculous and the mysterious may be inexplicable, but the response to it by many scientists has been quite predicable. They deny that such events exist and insist that there is some hidden variable that will make randomness disappear. They may, of course, be right, but I doubt it. Science has operated for so long in the rational paradigm where everything has an answer and closure is just a matter of removing ignorance, that the logos has become a kind of deity whose only support or proof is that using it in the past has worked. At least it worked in certain places. Complexity theory or chaos theory argues, however, that there are dimensions of reality or nature that are too complicated for anything as simple as algorithmic or mechanical reason.
Though complexity theory is lauded by many theorists, Gould and Lewontin among them, the dean of complexity theory is Stuart Kauffman, author of Origins of Order: Self Organization and Selection in Evolution and At Home in the Universe: the Search for the Laws of Self-Organization and Complexity.
Kauffman’s autocatalytic set theory is heavy going for the laymen, involving computer simulations of “chemical”automata that are assigned numbers (known as Boolean functions) and then let loose to interact by chance. The simulated interaction of this prebiotic soup of chemicals (automata) is unprogrammed and random. There is no way of knowing which chemicals (automata) are necessary for life to begin nor can one calculate or control which automata catalyze with each other. But at a certain point, the system often crosses a tipping point, becomes stable, and acquires a life of its own.
No DNA is involved here and no natural selection. It is simply an autocatalytic generation of life and DNA comes later. This theory challenges the standard model of Darwinian gradualism and of genetic reductionism. Life does not emerge fractionally over time, but like Botticelli’s Venus, at a certain point it springs full blown from the sea of chemicals.
It is no wonder then that Kauffman draws the ire of those who, like Dawkins, hold a monochromatic view of evolution. At the same time, of course, Kauffman annoys creationists because his theory does not mean that Homo sapiens had to evolve, but only that some form of life would evolve. Given a sufficient number of chemicals in the soup, some kind of metabolism will eventually occur.
There is, of course, no proof that this is the way life originated. Gradualists like Dawkins maintain that life evolved piecemeal. Nonetheless, Kauffman’s successful simulation certainly indicates that Darwinian theory may not provide a complete explanation of cells, organisms, and ecological systems.
If Kauffman attracts a lot of criticism from creationists who do not understand why he will not say that self-organization results from design, he also is in conflict with the pluralists because he does not believe that the emergence of intelligent life was a freakish happenstance. Like Wright and others, Kauffman shares the anthropic view that some kind of intelligent life had to evolve from the initial chemical soup produced by the “Big Bang.” As he put it in At Home in the Universe, humans or at least some form of intelligent life, are, because of the laws of complexity, “expected [and] at home in the universe.”
The only thing that bothers me in Kauffman’s autocatalysis is this bias toward intelligent life. If a random mix of chemicals can unpredictably generate life, why cannot the process also at a later time degenerate just as unpredictably? In chaos theory in physics, orderly systems appear from nowhere and disappear into the same place.
In any case, if complexity theory is correct, and if I understand it correctly, the implications for a rational theory of evolution are not promising. However much life might be necessitated in the original chemical broth, the particular form of life that evolved was random. Moreover, since each evolving organism interacts with and produces an effect on all other organisms, and all these organisms interact with and produce effects on the environment, there seem to be a near infinite number of possible courses for evolution to take. Chance, once thought to have been banished from the modern world, seems to lurk everywhere.
I ought to arrive at a conclusion here, but I’m not sure what it would be. I have a hard time accepting the idea that there is an intelligent design to this world of tragedy and just as hard a time accepting any reductionist view of its cause. Kauffman’s theory of intrinsic autocatalysis and contingency combined with Gould’s view of the forces of extrinsic contingency seems the most intellectually satisfying. Certainly Philip Johnson raises all the moral implications of accepting the meaninglessness of things, but accepting intelligent design just to avoid the Nietzschean abyss seems too artificial.
In some sense, of course, paleontology was an age old discipline. Ancient Greeks like Anaximander, Xenophanes, and Herodotus had suggested that the discovery of marine fossils in inland areas indicated that the earth’s geography varied in time. And, in the eighteenth century, Georges Cuvier and George-Louis Leclerc de Buffon had used fossil evidence to suggest that the age of the earth was much longer than tradition had held. Nonetheless, modern paleontology only began to emerge when Darwin suggested that there was a relationship between physical/climatic changes and the morphological change of plants and animals.
Darwin referred to the idea in chapter VIII ( “Principles of Sexual Selection”) of Descent of Man, under the subsection, Laws of inheritance. A fuller account is in The variation of Animals and Plants Under Domestication, 2 vols. (London: 1868), reprint (New York: AMS Publishing, 1972).
Origin of Species, Chapter V on “Laws of Variation,” subsection Effects of the Use and Disuse of Parts, as Controlled by Natural Selection, in Darwin, Vol. 49 of Great Books of the Western World, ed. Robert Maynard Hutchins, (Chicago: Encyclopedia Brittanica, 1952), p. 66.
 Genes are infinitesimal particles of DNA on the chromosomes of the cell. Stretched out and unwound, however, genes become yard-long molecules with a twisted ladder-like “double helix” shape. The rungs of the ladder join the two sides in a set of base pairs (bps) made up of one of four nucleotides, adenine, guanine, thymine, or cytosine, usually abbreviated as A, G, T, or C. This “alphabet,”with its near infinite number of base pair combinations and positions on the long molecule, is the genetic code. As with any piece of real estate, the key element of a gene is location, location, location; and for this reason genes are often referred to as specific loci on the double helix. For living organisms, these loci are all in very close proximity, with nearly all living organisms from worms to Homo sapiens sharing an unnerving number of genes. The genes provide instructions or codes for amino acids which build the proteins that manufacture parts and provide instructions for the functions and organs of the body.
Ernst Mayer and William B. Provine, The Evolutionary Synthesis: Perspectives on the Unification of Biology, (Cambridge: Harvard University Press, 1998).
Most genes come in pairs (are “diploid”), one from each parent, but the body also makes the germ cell or gamete which contain only half the necessary information (are “haploid”) and acquire the other half from the sperm or egg of the other parent. When the two haploid genes differ, as for example in eye color, the result is an allele, an alternative form of the gene. Where there are alleles, the dominant prevails over the recessive. As it matures, a body cell becomes a new body cell following the instructions of the genetic code in each cell. The organism, therefore, is the result of these genes and alleles. If a coding mistake occurs, natural selection normally eliminates it.
Unlike most abstract theoretical problems or controlled laboratory experiments, nearly all practical problems in the real world involve uncertainty. Stochastic programming is an effort to develop practical procedures for operating in an uncertain and unpredictable world. Such programming often employs computerized random number generators and is often used in non-linear theories with many variables. An example is demographics where climate, geography, predation, disease, and so on make prediction dicey. Stochastic is used more and more in theories of evolution, environment, finance, politics, in short, everywhere except in the realm where most academics dwell.. In the political realm, perhaps the most famous catalogue of such practical procedures, in politics would be Machiavelli’s Prince.
But some recent research has indicated quite the opposite, that is, the greater the size of the population, the greater the chance of fixation. See, for example, Jeffrey McKee, The Riddled Chain: Chance, Coincidence, and Chaos in Human Evolution, (New Brunswick: Rutgers University Press, 2000), pp. 234ff.
Though de Vries continued to use the term “pangene,” it may well have been because of his work that the term was abandoned ( a suggestion of W. L. Johannsen (1857-1927) in favor of “gene”which did not have the “blending” and “continuous variation” baggage of the former term.
In the first place, mutant alleles are often quickly eliminated. Some researchers even argue that sexually active females become pregnant during every menstrual cycle and then naturally and unobtrusively abort because the fetus is a mutant. Second, aside from being quickly eliminated, mutant alleles are often recessive and do not announce themselves until the allele of an individual many generations later is joined by a reprint of the mutant. Thirdly, many researchers argue that most mutations are neutral, invisible, and never have any effect. Others argue that a mutant allele may not produce any effects unless it happens to be near another “trigger allele” on the DNA molecule. And if all this is not enough, the phenotypical result of a mutant allele may vary in individuals and mask its origin. For these reasons and many others, many if not most laboratory mutation experiments are performed on relatively “simple” haploid bacteria. This may help us understand the way, say an antibiotic resistant strain of bacteria has mutated, but it is still for off from the more complicated studies of human mutation.
Allopatric implies separation because of a physical (glacial, volcanic, etc), A similar concept is known as peripatric which describes species at the periphery of a population but not separated physically.
Populations can also be isolated because they have adapted to some local habitat and are called parapatric.
There is, obviously, a large investment in the theory of gene drift here for without it, speciation becomes more difficult to explain. Still, some do question whether gene drift actually exists. Perhaps genes lie dormant in a large population and then for some reason appear, become fixed in some individuals who then breed and produce a new species. Such a notion would involve sympatric speciation, that is the evolution of different species from one population rather than many isolated ones. Sympatric speciation is out of favor, but the etiology of a new allele is no easy thing to track down. The unknown already plays so large enough role in the macro world of tracing individual genealogies back through missing, damaged, records, adoptions, the subterfuges of the unfaithful wife, (the so-called “milkman effect”) and so on, that it is difficult if not impossible to really know the source of an allele. And when one enters the microscopic world, things become even more complex. Consider only the possible problem raised by some researchers of “polymorphism,” that is the existence in an individual of multiple functionally equivalent alleles, anyone one of which could take command in the offspring. Polymorphism allows for variation in such things as eye color, blood type, hair color, stature as well as exotic morphologies. How is one to know whether the appearance of an odd allele in the past occurred because of gene drift, gene flow, or had simply been dormant in a polymorph for a long period?
Scientific American, for example, refused Phillip Johnson, Professor of Law at the University of California at Berkeley, the right to respond to a hostile review of his Darwin on Trial by Stephen Jay Gould. See editor’s note, to Phillip Johnson,“The Real Issue: The Religion of the Blind Watchmaker,” Origins, cited from the net, February 25, 2001. Www.origins.org/real/ri9203/watchmakr.html.
 Robert Wright, “The Accidental Creationist: Why Stephen Jay Gould is bad for evolution,” New Yorker, December 13, 1999.
“The Cheshire Cat’s DNA,” New York Review of Books, (December 21, 2000), p. 46.
(New York: Vintage, 1995; orig, 1994)
See for example, George C. Williams, Natural Selection: Domaines, Levels, and Challenges (1992), [a defense of the gene as the primary vehicle of selection], Adaptation and Natural Selection, (1966) [his defense of evolution as occurring individual organisms rather in entire groups] J. Maynard Smith and Eors Szathmary, Origins of Life: From the Birth of Life to the Origins of Language, (Oxford: Oxford University Press, 1999) which is a layman accessible revision of the earlier Major Transitions in Evolution; the famous geneticist, Seymour Benzer [on Benzer, see J. Weiner, Time, Love, Memory A great Biologist and His Quest for the Origins of Human Behavior, (New York: Knopf, 1999)]; Edward O Wilson, Sociobiology: The New Synthesis, (Cambridge, Harvard University Press, 1975); On Human Nature, (Cambridge: Harvard University Press, 1978); Biophilia, (Cambridge: Harvard University Press, 1984), The Diversity of Life, (Cambridge: Harvard University Press, 1992); Consilience: The Unity of Knowledge, (New York: Knopf, 1998); and Dawkins, The Selfish Gene, (Oxford: Oxford University Press, 1976); The Extended Phenotype; (Oxford: Oxford University Press, 1982); The Blind Watchmaker. (New York: Norton, 1986) and Unweaving the Rainbow. (New York: Houghton Mifflin, 1998).
Adaptation and Natural Selection (Princeton: Princeton University Press, 1966)
Richard Dawkins, “Human Chauvinism,” review of Stephen Jay Gould Full House in Evolution (vol. 51, 1997, no. 3 cited from the net February 26, 2001. www. world-of-dawkins.com/fullhouse.html
See for example his “Postmodernism Disrobed,” Nature 394, (July 9, 1998), pp. 141-143.
Richard Dawkins, “Sociobiology: the debate continues,” review of Steven Rose, Leon J. Kamin, R.C. Lewontin, Not in Our Genes:Biology, Ideology, and Human Nature in New Scientist (24 January, 1985), cited from net waw. world-of-dawkins.com/notinourgenes.html
See for example the Dawkins interview “Richard Dawkins on Evolution and Religion,” with Ben Wattenberg on the PBS program Think Tank, aired November 8, 1996. The interview is on line and can be found www.world-of-dawkins-.com/thinktnk.html.
See his review of Steven Rose, Leon J. Kamin, R.C. Lewontin, Not in Our Genes: Biology, Ideology, and Human Nature (London: Panthoen, 1985) in New Scientist 24, 1985) www.world-of-dawkins.com/notinourgenes.html
”What Your Genes Reveal About You,” The Independent, (February 24, 1997), p 15.cited from the net www.world-of-dawkins.com/what-your-genes-reveal.html
Richard Dawkins, Free Inquiry, Summer 34-41 (1993) cited from the www.santafe.ed/~shalizi/dawkins/viruses-of-the-mind.html
Simply exploring the parameters of this superheated debate could occupy a warren of graduate students for a decade and I will just hint at some of the dimensions. At the simplest and perhaps the most sane level, there is the debate between those who believe there is a human nature that scripted more by biology than culture and those who hold that culture to some extent can trump biology. As one moves farther to the extremes of this debate, suspicions rise about cultural relativism, the supposed absence of biological gender differences, the work of Franz Boas, Margaret Meade, and Ashley Montagu, and, entering areas where angels fear to tread, ponder the genetics of race and homosexuality, At the other end of the spectrum, the defenders of culture deny that a human nature exists at all, see no biological gender differences, denounce Darwin as a White Victorian Male, and dismiss biology as epiphenomenal. Generally, but not always, the debate is between liberals who defend cultural relativism, environmental determinism, and human malleability and conservatives who believe in human nature, more or less absolute values, and doubt the possibility of human melioration.
This “culture war” became a hot war after Alan Sokal, troubled by fashionable postmodern attacks on science, succeeded in having a nonsense article (“Transgressing the Boundaries: Towards a Transformative Hermeneutics of Quantum Gravity”) published in Social Text 46/47, Spring/Summer, 1996, pp. 217-252), a journal associated with elites like Fredric Jameson and Andrew Ross. He then revealed the hoax in “A Physicist Experiments with Cultural Studies,” Lingua Franca (May/June 1996), pp. 62-64. In the biological world, the spectrum runs from more dogmatic biological determinists like E. O. Wilson and David Barash, to figures like Steven Pinker, Robert Wright, Daniel Dennett, Dawkins who (reluctantly) allow for some input by culture, to more middle grounders like Paul Gross and Norman Levitt who make a sensible case for the scientific perspective, Gould, Lewontin, Barbara Ehrenreich, and Ruth Hubbard who see the Holy Grail of the Human Genome as a fantasy but accept certain biological parameters in gender differences, to, on the other side, philosophers of science like Bruno Latour who really do understand that a lot of what passes for science is in fact constructed, feminists who deny biological differences between the genders, and fringe elements who deny the existence of DNA.. The attack on science is so strong that some, even from the left, view it as a kind of creationist flat earth opposition. See, for example, Barbara Ehrenreich and Janet MacIntosh, “The New Creationsts: Biology Under Attack,” The Nation, June 9, 1997; and Patrick Sand, “Left Conservatism,” Nation, (March 9, 1998). The polemic between socio-biology and the politically correct view that human nature is a construct is strewn all over the popular and scientific literature. For some of the more provocative literature on both sides, see the various debates on Richard J. Herrnstein and Charles Murray, The Bell Curve: Intelligence and Class Structure in American Life, (Cambridge: Harvard University Press, 1994), for example, the two reviews by the evolutionary psychologist Thomas J. Bouchard on the one hand and the liberal Donald D. Dorfman in Contemporary Psychology, vol. 40, no. 5, (May 1995). Important literature on the socio-biological side is Matt Ridley, The Red Queen: Sex and the Evolution of Human Nature (New York: MacMillan, 1994); The Origins of Virtue:Human Instincts and the Evolution of Cooperation, (New York: MacMillan, 1997) Steven Pinker, The Language Instinct (New York: Harper Collins, 1994); How the Mind Works, New York: Norton, 1997); Anne. Moir and David. Jessel, Brain Sex: The Real Differences Between Men and Women, (New York: Dell, 1991).On the other side, see Ann Fausto-Sterling, Myths of Gender (1992); Jerome Kagan, Three Seductive Ideas, (Cambridge: Harvard University Press, 1999)
The dust has not settled yet on this issue, however, for some argue that only “traditional” gender roles are imposed. Homosexual behavior, according to politically correct biology, is genetic; and fleet-of-foot biologists and other scientists in that camp have set to work to find examples of homosexuality all over the animal kingdom. See, for example, Bruce Bagemihl, Animal Exuberance: Animal Homosexuality and Natural Diversity, (New York: St. Martins, 1999); Noreen O’Conner and Joanna Ryan, Wild Desires and Mistaken Identities:Lesbianism and Psychoanalysis, (London: Virago, 1993). The political nature of sexual dissidence is discussed in Johnathan Dollimore, Sexual Dissidience: Augustine to Wilde, Freud to Foucault, (London: Clarendon, 1991)
According to the late Motoo Kimura for example, a species’ evolution or survival has nothing to do with its designing an increased reproductive ability but is a result of simple chance. The Neutral Theory of Molecular Evolution (Cambridge, Cambridge University Press, 1983).
H. Allen Orr, “Dennett’s Strange Idea,” review of Dennett’s Darwin’s Dangerous Idea, (New York: Simon and Schuster, 1996). cited from the net March 22, 2001 www.polisci.mit.edu/bostonreview/BR21.3/Orr.html
This does not deny that survival to a reproductive age is aided by sound engineering. It simply means that the engineering is the blind product of trial and error and “sound” only so long as all others things remain equal, in other words, for a very short time. Francois Jacob has a witty and deep book on this subject. See, Of Flies, Mice, and Men, trans. Giselle Weiss, (Cambridge: Harvard University Press, 1999)
Three Scientists and their Gods: Looking for Meaning in an Age of Information (which won the National Book Critics Circle Award in 1988) and The Moral Animal: Evolutionary Psychology and Everyday Life (which according to the New York Times was one of the “best books” of 1994) and most recently, Non-Zero: The Logic of Human Destiny (2000).
 Recent research with E.coli bacteria may have confirmed such rapid speciation. See, S. F. Elena, V. S. Cooper, and R. E. Lenski, “Punctuated Equilibrium Caused by Selection of Rare Beneficial Mutations,” Science Magazine, No. 5269, Vol. 272, (June 21, 1996),
Moreover, such events can, according to taphonomists who study the process of fossilization, preserve or hinder (or utterly destroy) fossils or, certain parts of organisms. Moreover, since harder parts of an organism fossilize more easily than softer, the record is by nature spotty.
Both texts, Cambridge: Harvard University Press, 2000
Wonderful Life: The Burgess Shale and the Nature of History, (New York: Norton, 1989), p. 291
The Crucible of Creation: The Burgess Shale: The Burgess Shale and the Rise of Animals (Oxford: Oxford University Press, 1989). On the other hand, to biologists like Simon Conway Morris, argue that the underlying structure of the creatures of the Burgess fit into or between known phyla quite well and only diverge superficially or when viewed carelessly. Likewise, Dawkins notes that the fact that 550 year-old fossils are not congruent with modern phyla does not mean that they were not closely related 550 million years ago.
Originally in 1979 and now in Conceptual Issues in Evolutionary Biology, (Cambridge: MIT Press, 1984) pp. 581-598.
Pp. 582-5. Though the point about evolution seemed valid, Dennett could not resist attacking it in Darwin’s Dangerous Idea where he said a spandrel was really a pendentive and was intentional anyway.
See, for example, Richard Lewontin, Stephen J. Rose, and Leon J. Kamin, Not in our Genes: Biology, Ideology, and Human Nature, (New York: Random House, 1984); Lewontin, Human Diversity, (Boston: Scientific American Library, 1995).and, most recently, Lewontin, The Triple Helix: Gene, Organism, and Environment, (2000)
Gould’s and Lewontin’s debt to Marxism is well known. See for example the preface to Gould, Full House, Lewontin and Richard Levins, The Dialectical Biologist, (Cambridge: Harvard University Press, 1985). Discussions, critiques, and an astonishing trip through biology as Marxism, subversion, Semitism, anti-Semitism, class warfare, egalitarianism, and a half-dozen other “isms” can be found in Dennett, Darwin’s Dangerous Idea, (1995), in the works of and reviews of Kevin MacDonald, The Culture of Critique: An Evolutionary Analysis of Jewish Involvement in Twentieth-Century Intellectual and Political Movements, (Westport CN: Greenwood Press, 1998) Michael Ruse, “Transcript: Speech by Professor Michael Ruse,” to the American Academy for the Advancement of Science at the Symposium “The New Antievolutionism,” (Feb. 13, 1993,) from the net on July 1, 2001 at www.leaderu.com/orgs/arn/orpages/or151/mr93tran.htm. All of this barely scratches the surface of this debate.
The Crucible of Creation: The Burgess Shale and the Rise of Animals, (Oxford: Oxford University Press, 1999)
See chapter one of The Crucible of Creation
See Chapter 8 of The Crucilbe of Creation
(Oxford:Oxford University Press, 1988)
David Reynolds, One World Divisible: A Global History Since 1945, (New York: Norton, 1945)
 p. 272.
(New York: The Free Press, 1998)
H. Allen Orr, “Dennet’s Strange Idea,” a review of Dennett’s Darwin’s Dangerous Idea, on the net.op.cit.
Denton’s argument is similar to that set out by Michael Behe in Darwin’s Black Box. Denton says intermediate species do not exist; Behe says they cannot exist..
Denton, p. 296
p. xii. On p. 76: “The atom-building system is designed specifically to generate the elements of life.”
Oxford: (Oxford University Press, 1993.
 Oxford: Oxford University Press, 1995.
Named after the British mathematician George Boole, they permit automata (like the search engine of a computer) to make choices between “this,” “that,” “this and that,” “this or that,” or, as in this case, to make random choices.