Friday, April 25, 2008

Connecting Hitler and Darwin (or Luther?): David Berlinski's Sophistry

The last third of Ben Stein's movie Expelled claims that there is a direct connection from Charles Darwin to Adolf Hitler and the Holocaust. This is supposed to show how morally corrupting Darwinian biology can be. To support this conclusion, Stein interviews Richard Weikart, the Discovery Institute historian who wrote From Darwin to Hitler. Stein was very careful not to interview any historians who dispute Weikart's claims, because this would have weakened the propaganda value of the movie.

David Berlinski, another Discovery Institute fellow who was in the movie, has now written an article defending this part of the movie. Here is how he puts his argument:

"One man--Charles Darwin--says: 'In the struggle for survival, the fittest win out at the expense of their rivals.'

"Another man--Adolf Hitler--says: Let us kill all the Jews of Europe.

"Is there a connection?

"Yes obviously is the answer of the historical record and common sense."

Really? Is this connection obvious?

In Darwinian Conservatism and in many posts on this blog, I have argued that Weikart's putative connection "from Darwin to Hitler" is very weak. For example, one of the obvious weaknesses in this argument is that there is no anti-Semitism in Darwin's writing. If one were looking for the source of Hitler's anti-Semitism, one might consider Martin Luther. Luther's "On the Jews and Their Lies is one of the most repugnant expressions of anti-Semitism in European history. Scholars such as Richard Steigman-Gall--in his book The Holy Reich--have shown the immense influence of Luther on the Nazis.

So what does Berlinski say about the Luther connection? "A professor of theology at Iowa State University, Hector Avalos, is persuaded that Martin Luther, of all people, must be considered Adolf Hitler's spiritual advisor. Luther, after all, liked Jews as little as Hitler did, and both men suffered, apparently, from hemorrhoids." That flippant comment is all Berlinski says about this. For him, that's enough. There's no need to confront the scholarly record on the history of Luther and anti-Semitism in Germany, because that might upset the rhetorical strategy of the Discovery Institute.

Astonishingly, Weikart never mentions Luther, because this would weaken his argument that Christianity promoted the equal moral dignity of all human beings against the degrading materialism of Darwinism. Of course, Weikart could rightly argue that Luther's anti-Semitism was a distortion of the Christian tradition. But then wouldn't he also have to consider the possibility that social Darwinism was a distortion of Darwinian science?

Weikart has written a hostile review of Steigman-Gall's book. But almost everything he says in criticizing Stegman-Gall's connecting Nazism to Christianity could easily be said in criticizing Weikart's connecting Nazism to Darwinism. For example, Weikart says that if one looks closely as the Nazi interpretations of Christianity, one can see that "their Christianity was always interpreted through the lens of their racial ideology, not vice versa." Yet the same could be said about the Nazi interpretations of Darwinism!

In the movie, neither Berlinski nor Weikart ever mention this debate over whether Luther is a better source for Nazism than Darwin, and Stein never raises this as a question. To have raised such questions would have provoked some deep thought about the issues, and that would have subverted the sophistical rhetoric of this movie.

The Individuality of Bacteria

One of the most common misconceptions about the biological study of life is that it promotes a determinism that denies individuality and freedom. That's one of the primary reasons why conservatives fear any biological account of human life. They also fear that the genetic determinism of modern biology prepares the way for a genetic engineering of life that will bring a dehumanizing tyranny leading to what C. S. Lewis called "the abolition of man."

Against this misconception, I have argued in a recent post that biological science shows the natural ground for the "Individuality, Contingency, and Historicity of Life." For example, I pointed to the individuality of bacteria: even when bacteria are genetically identical, their behavior differs in ways that show the uniqueness of each bacterium.

Now, in a recent article in the New York Times, Carl Zimmer summarizes some of the recent research confirming this point. E. coli is a species of bacteria that lives in our gut, and it is one of the model organisms for biological research, particularly in genetics. He writes: "A colony of genetically identical E. coli is, in fact, a mob of individuals. Under identical conditions, they will behave in different ways. They have fingerprints of their own."

In a sense, E. coli has "personality"--distinct traits for each individual that cannot be explained by genetics alone. The reason for this is that unlike simple machines, living organisms show an "unpredictable noisiness" in their biological operations so that genetically identical individuals act differently in ways that are not controlled by their genes. Such unpredictable differences are advantageous for evolution, because it allows some individuals to survive in harsh environments when many others die.

If the social sciences and the humanities are to be linked to the natural sciences, that link will come through the life sciences rather than the physical sciences, because the life sciences confront the same individuality, contingency, and historicity that characterize social behavior and human life.

Monday, April 21, 2008

The Shameful Sophistry of the Intelligent Design/Evolution Debate

As I have indicated in my previous post, Ben Stein's movie Expelled is a crude piece of propaganda for "intelligent design theory" that insults the intelligence of the audience. But the response of the defenders of evolutionary theory is just as crude. Over at the "Panda's Thumb" blog, they're gloating that the box office receipts for the movie haven't made as much money in its first week-end as was expected. It's clear that neither side in this debate cares about the intellectual content of the issues. What they care about is victory over their adversaries.

This is the tradition of the Greek sophists--those who claimed to be philosophers thinking about the deepest issues of human existence, but who really only cared about winning the glory of victory over their opponents.

Does the Discovery Institute want to promote intellectual inquiry into the origins of life and the profound implications of this for human existence? Or does it want to promote the political agenda of intelligent design creationism against its adversaries? Similarly, do people like Richard Dawkins and bloggers like those at "Panda's Thumb" really want to think through these issues and exchange ideas in ways that deepen our understanding? Or do they want to defeat their opponents?

Isn't the answer obvious? There is no interest in carrying on a serious intellectual inquiry into these great human questions. The interest is in winning victory for one's side and defeating the opponents.

There is no evidence in Ben Stein's movie that he wants to think through these questions for himself or help others to think through them. But at the same time, there is no evidence that his opponents--like those at "Panda's Thumb"--want to promote serious thinking about these questions. All these people really care about is claiming some victory for themselves against those opponents.

Am I being naive in thinking that some human beings care more for understanding the deepest human questions than for victory over their intellectual opponents? Is there something in human nature--the desire for dominance over others--that makes the love of victory stronger in most human beings than the love of wisdom?

Saturday, April 19, 2008

The Rhetorical Blunder in Ben Stein's EXPELLED

Ben Stein's movie Expelled: No Intelligence Allowed opened yesterday in theatres around the nation. This movie is the latest project of the Discovery Institute in promoting the political rhetoric of "intelligent design theory" as the alternative to Darwinian evolutionary science. The National Center for Science Education has set up a good website that corrects the many mistakes in the movie.

The folks at the Discovery Institute have made a big mistake in their production of this movie. The political rhetoric of the Discovery Institute's "wedge strategy" depends upon hiding a fundamental contradiction. But this movie makes the contradiction so evident that any viewer can see it. On the one hand, the rhetorical strategy of the Discovery Institute is to say that "intelligent design" is not a creationist religious belief but pure science, and therefore teaching "intelligent design" in public high school biology classes does not violate the First Amendment's prohibition on establishing religion. On the other hand, the popular success of the Discovery Institute's rhetoric depends on appealing to Biblical creationists who assume that "intelligent designer" is just another name for God the Biblical Creator.

This contradiction--both affirming and denying that "intelligent design theory" is the same as Biblical creationism--became evident in the 2005 case in Dover, Pennsylvania. Leaders of the Dover Area Public School board wanted to teach Biblical creationism. They were warned that this would violate U.S. Supreme Court decisions declaring that teaching creationism as science violated the First Amendment separation of church and state. They then decided to teach "intelligent design theory" as a disguised form of Biblical creationism. The trial made clear their deception, and this also exposed the contradiction in the Discovery Institute's rhetoric.

Rather than covering up this contradiction, this movie makes it hard for any viewer to ignore the contradiction. When Bruce Chapman--President of the Discovery Institute--is interviewed by Stein, Chapman says that journalists distort the true position of intelligent design by saying that it's a creationist religious belief, because the "intelligent designer" is clearly God. Chapman vehemently denies this. But then for the rest of the movie, it's asserted that anyone who denies "intelligent design" is therefore an atheist who denies the existence of God!

Viewers of the movie who know nothing about the debate over intelligent design will easily see this contradiction. Those who do know something about the debate will notice another indication of the contradiction--the absence of Michael Behe. Stein interviews almost all of the major spokesmen for intelligent design. The one remarkable exception, however, is Behe--the LeHigh University biologist who until recently has been the star scientific witness for intelligent design theory.

As I indicated in a blog post last year, Behe's most recent book is is strong attack on biblical creationism. Behe concedes so much to Darwinian science--the limited power of natural selection working on random mutation, evolution by common descent, the evolution of human beings from primate ancestors shared with chimpanzees, rejection of Biblical creationism as "silly," and support for theistic evolution--that Behe actually subverts much of the moral and religious agenda of the Discovery Institute. Behe even questions the goodness and omnipotence of the intelligent designer in deliberately creating malaria! The remarkable absence of Behe from this movie indicates that Behe's positions are no longer helpful to the Discovery Institute's rhetoric.

There are many other weaknesses in the rhetoric of this movie, but they are weaknesses that I have already taken up in many previous posts on intelligent design reasoning. The last third of the movie is devoted to Richard Weikart's "Darwin to Hitler" argument that I have analyzed in various posts. As is usual, a quotation from Darwin's Descent of Man is used to suggest that Darwin promoted something like Nazi eugenics. But the quotation is taken out of context to hide the fact that Darwin rejected the eugenics of Francis Galton. I refer you to my various posts on the issue of Nazi eugenics.

The movie assumes that evolutionary science must be atheistic. To support this assumption, Stein is careful only to interview people like Richard Dawkins who are atheistic evolutionists. He is very careful not to interview theistic evolutionists like Ken Miller or Francis Collins, or even someone like Behe who argues that God might have worked through an evolutionary process. Stein also is careful not to quote from any of Darwin's references to God as Creator.

Consider how different this movie would have been if Stein had interviewed someone like Francis Collins. Collins could have explained how reading C. S. Lewis helped to convert him to Christianity. He could also have explained how he as a geneticist accepts evolutionary science as supported by the evidence and rejects "intelligent design theory" as unfounded. He could have indicated how he sees evolution as compatible with his Christian beliefs and why he rejects Richard Dawkins' atheism as not based on science. Such an interview would have raised some deep questions about the relationship between science and religion--questions that would have been intellectually challenging to the viewers. But Stein chose not to do anything like this. Why? Because it would have subverted his intention in producing a crude piece of propaganda that insults the intelligence of his viewers?

The movie also assumes that evolutionary science denies morality and promotes moral nihilism. To support this assumption, Stein is careful to interview only people like Will Provine who interprets evolution in a nihilistic manner. But this means that Stein has to be very careful not to interview people like David Sloan Wilson who emphasize Darwin's theory of the "moral sense."

A big part of this movie argues that scientists who question Darwinian science or suggest the possibility of intelligent design are censored or otherwise punished and thus their intellectual freedom of thought is denied. The NCSE website surveys the evidence in these cases and indicates how the movie distorts the facts. The one case that might support the movie's argument is that of Guiellermo Gonzalez, an astronomer who was denied tenure at Iowa State University in the Department of Physics and Astronomy. From what little I know of this case, it does appear that Gonzalez has a pretty good record of academic research that might justify tenure, and so it's possible that his support for intelligent design might have provoked some unfair bias against him. The problem, however, is that the policy of confidentiality in academic tenure cases makes it hard to know for sure what motivated the people involved.

I agree on the importance of freedom of thought in these matters. I have argued on this blog and elsewhere that biology classes--both at the high school level and at the college and university level--should be open to discussion of "intelligent design theory" as a possible alternative to Darwinian science. As I have indicated, I don't find the arguments and evidence offered by the ID proponents persuasive. But I see nothing wrong in allowing students to debate this in their biology classes. I have promoted such open debate in my own university classes.

The problem, however, is that both sides of this debate are caught up in a frenzy of rhetorical posturing that makes it impossible to have a thoughtful exchange of competing ideas. I have seen this on those many occasions when I have debated these folks in public. This movie is an example of the rhetorical distortions that make me wonder whether I am being naive in thinking that students and scholars should be able to debate these vital questions in an open and honest manner.

A few of my blog posts relevant to these issues can be found here, here, here, here, here, here, here, here, and here.

My argument for "teaching the controversy" by teaching Darwin has received some coverage in Inside Higher Ed, which can be found here and here.

One of my first essays on "intelligent design theory" for in 2001 can be found here.

I also have a chapter on intelligent design in Darwinian Conservatism.

Last year, I debated intelligent design at the American Enterprise Institute with John West and George Gilder. The New York Times article on the debate can be found here. A podcast of this AEI debate can be found here.

Monday, April 14, 2008

The Hero with Twenty Faces: Darwinian Literary Studies

In teaching my graduate seminar on "American Political Novels," I have thought about how Darwinian science might illuminate the study of literature. Professional scholars in literary studies usually assume that literature belongs to the humanistic disciplines that must be radically separated from the natural sciences generally and from biological science in particular. But a small group of literary scholars have recently begun to apply Darwinian psychology to the study of literature. A couple of years ago, The New York Times Magazine published an article surveying the work of these folks--D. T. Max, "The Literary Darwinists" (November 6, 2005). One of the best of these scholars is Joseph Carroll, and he offers a good analysis of this research in his contribution ("Literature and Evolutionary Psychology") to The Handbook of Evolutionary Psychology (2005) edited by David Buss.

I would say that literature is an emotionally-charged imaginative simulation of human experience. Literature has a universal appeal in so far as it explores a universal human nature. A Darwinian science of human evolution would account for human nature as manifested in the twenty natural desires that I have sketched out in various places. Literature engages our interest because it depicts the conflicts that arise within and between individuals as they strive to satisfy those natural desires over the course of their lives.

Literature displays not only the universality of human desires but also the cultural and individual variability in the expression of those universal desires. This creates the interesting complexity in human experience in which natural desires constrain but do not rigidly determine the customary traditions of social life and the variable temperaments of unique individuals. Literature helps us to understand and manage this complex interaction of universal nature, customary traditions, and individual choices.

Joseph Campbell's famous book The Hero with a Thousand Faces argues that literature around the world and throughout history portrays certain mythic archetypes that evoke a universal human psychology, which he thought was best explained by Carl Jung's psychoanalysis. I would see this as showing the universality of the twenty natural desires, which could be best explained as arising from the evolved nature of human beings.

In some ways, there is nothing new about this. Beginning with Aristotle's Poetics, students of literature have seen it as an artistic imitation of human nature. But the strength of Darwinian literary theory is that it offers a scientific explanation for the universal human nature that traditional literary scholarship has simply taken for granted.

Moreover, a Darwinian approach to literature can challenge those contemporary schools of literary study that deny human nature. Feminist theorists, for example, have argued that gender identity in European literature is an arbitrary social construction to enforce the patriarchal subordination of women to men. By contrast, Darwinian psychology would predict that although there will be great cultural and individual variation in the sexual differentiation of males and females, this variation will be constrained by the natural differences in the mental and behavioral propensities of men and women. This would predict that across all cultures, there should be certain regularities in the literary depiction of men and women. So even if there is much in the novels of Jane Austen that reflects the peculiarities of courtship and marriage in nineteenth-century Victorian England, her novels should also show some universal patterns of sexual mating that would be found in all cultures throughout history.

Tuesday, April 08, 2008

Against "the Conservatism of Slavery"

In Darwinian Natural Right, I have a chapter on slavery that shows how a Darwinian view of morality allows us to recognize the immorality of slavery while exercising prudence in managing the tragic conflicts that slavery has created in history. On this blog, I have have posted a series of comments on the similarities between Abraham Lincoln and Charles Darwin in this opposition to slavery.

Unfortunately, some American conservatives who look to the Southern tradition of political thought try to justify slavery in the American South as a natural and customary institution supporting liberty. In his comments in The Conservative Mind on the Southern conservatism of John Randolph and John C. Calhoun, Russell Kirk observed that "human slavery is bad ground for conservatives to make a stand upon." But, even today, some conservatives disregard Kirk's warning.

For example, the fall 2007 issue of Modern Age has a collection of articles on American intellectual conservatism that includes a section on the "defense of the Old Republic," and the "Old Republic" turns out to be predominantly the "Old South" and its institutions. One of the articles is "The Old Republic and the Sectional Crisis" by Mark Malvasi. According to Malvasi, the demise of the "Old Republic" came with the defeat of the South and the emancipation of slaves in the Civil War. He criticizes Lincoln for leading those Republicans who "knowingly misrepresented" slavery as "a departure from the original intentions of the Founding Fathers." Malvasi quotes a Southern congressman as warning his Northern colleagues that "the conservatism of slavery may be necessary to save you from the thousand destructive isms infecting the social organization of your section." Malvasi notes that the proslavery Southerners were Christians who believed the Bible supported slavery as necessary for a good social order. "For men who took seriously the biblical injunction to be their brothers' keepers, slavery was the best, if not the only, means of preserving a Christian social order in the modern world."

Malvasi's defense of "a genuinely Christian slavery" as the foundation for the conservatism of the "Old Republic" is a disturbing manifestation of the intellectual and moral confusion in contemporary conservatism. A Darwinian conservatism would escape such confusion by showing how conservative thought can be rooted in prudence and Darwinian natural right, which allows us to recognize the evil in practices like human slavery.

Some of my posts on Darwin, Lincoln, and slavery elaborate these points. Some of them can be found here, here, here, and here.

Wednesday, April 02, 2008

Good Eugenics

Critics of Darwinian conservatism--John West, for example--often argue that the history of eugenics illustrates the morally repugnant consequences of Darwinian thinking. In my chapter on "Social Darwinism" in Darwinian Conservatism and in various posts on this blog responding to West, I have suggested that for Darwin, eugenics--the management of human breeding to promote the physical and mental health of the offspring--can be either good or bad. Eugenics is good when it is based on a realistic understanding of our limited knowledge of biological inheritance, and when it is guided by a moral sympathy for the weaker members of society. Eugenics is bad when it is motivated by a utopian vision of human perfectibility through the breeding of superior races, and when it is unchecked by humanitarian sympathy. Darwin promoted good eugenics, as in his concern about the consequences of incest and cousin marriage. Francis Galton promoted bad eugenics rooted in a tradition of utopian eugenics that began with Plato's Republic. Like Plato, Galton described his eugenics as directed to producing "a race of gifted men," so that "the utopias in the dreamland of philanthropists may become practical possibilities."

Good eugenics would allow parents to exercise prudence in making informed decisions about reproduction to satisfy their natural desire for parental care. We need prudence to decide particular cases where no absolute rule would work because of the contingencies and uncertainties in each decision. And we need to rely on parental care (as one of the 20 natural desires) to guide such decisions as conforming to our human nature.

As an illustration of such good eugenics, consider the recent article by Wesley Smith in The Weekly Standard. Smith is a senior fellow at the Discovery Institute who campaigns against abortion and what he calls "politically correct eugenics." But in this article, he implicitly supports what I would call good eugenics by supporting some legislation proposed by Senators Edward Kennedy and Sam Brownback. The legislation would require that parents making decisions about pre- and postnatal disabilities be given full information about "life expectancy, development potential, and quality of life" for children born with genetic disabilities such as Down syndrome. Smith hopes this would persuade many parents to care for Down children once they learn that such children can live good lives. He quotes from one parent of a Down child who decided that "Down's syndrome is not an insupportable horror for either the sufferer or the parents." Smith cites this parent's report as showing "the joy that many parents of Down children discover." He supports the Kennedy/Brownback legislation because it would allow parents to make a "fully informed decision," which might be a decision to care for a Down child as a joyful experience.

We allow parents to make such reproductive decisions because we assume that most parents will be motivated by a desire for parental care that considers the best interests of their children. Using governmental coercion to force a decision on them would be bad eugenics. Allowing them to make their own decisions based on the best available information and their natural desire for a healthy family life is good eugenics.

The Individuality, Contingency, and Historicity of Life

One objection to Darwinian conservatism is that a Darwinian view of evolved human nature opens the way to the use of biotechnology to change, or even abolish, human nature. Some conservatives worry that even if Darwinian biology denies the utopian belief of the left in human perfectibility through social engineering, this still leaves open the possibility of perfectibility through biological engineering. These conservatives share Leon Kass's worry that biotech is leading us to a "posthuman" future that will bring what C. S. Lewis called "the abolition of man."

In response to this objection, I have argued that people like Kass have exaggerated the power of biotech for changing human nature. They fail to see that biotech will always be limited in its power by the historical indeterminacy of living nature.

We commonly classify biology along with physics and chemistry as belonging to the natural sciences, which we distinguish from the social sciences such as economics and political science and the humanistic disciplines such as history. But I agree with biologists such as Ernst Mayr and Jared Diamond who argue that the fundamental distinction is between historical sciences and nonhistorical sciences, and that biology belongs to the historical sciences, along with economics, history, and political science, while physics and chemistry belong to the nonhistorical sciences.

For each kind of elementary particle studied by physicists and for each kind of molecule studied by chemists, the individual members of the class are identical. And consequently, physicists and chemists can formulate universal deterministic laws, at least at the macroscopic level. But in the historical sciences, the objects of study display a radical individuality in that each member of a class is unique. So, for the social scientist, every human society is unique, and every member of each society is unique. For the biologist, every species is unique, and every member of each species is unique. Even genetically identical bacteria grown in homogeneous conditions show unique individuality in their behavioral movements that persist over their lifespans. Consequently, social scientists and biologists can formulate probabilistic regularities but not deterministic laws. The phenomena studied in the historical sciences show emergent complexity, in that they must be consistent with the deterministic laws of physics and chemistry, but they cannot be reduced to those laws.

Consider, for example, Jane Goodall's magnum opus The Chimpanzees of Gombe. As the title suggests, this book gives a historical narrative of one unique group of chimpanzees in the Gombe Stream Preserve in Tanzania, and yet it also generalizes about probabilistic tendencies in all chimpanzee groups. So, for example, she narrates the history of the male dominance hierarchy in Gombe, which reflects the unique personalities and unique social circumstances of the Gombe chimps. She can generalize about how any chimpanzee group will tend to display a male dominance hierarchy, but she cannot predict the precise historical pathway for any particular chimpanzee dominance hierarchy. Moreover, she notices that different chimpanzee groups have different cultural traditions of behavior reflecting unique cultural histories. And now many primatologists have confirmed that chimps show complex patterns of cultural learning and tradition that resemble those of human beings. The uniqueness of each chimpanzee individual and the uniqueness of each chimpanzee group give rise to historical traditions of behavior that cannot be precisely predicted by deterministic laws.

It is true that all life depends on genes and a shared genetic code, which allow us to formulate general laws of life, and that through biotech, we can use our knowledge of those genetic laws of life to gain some power over living nature. But although genes are necessary for explaining life, they are not sufficient. And, furthermore, the complexity of genetic causality introduces historical contingency in ways that make it impossible to develop deterministic laws of behavioral genetics.

From the earliest days of genetics, beginning with T. H. Morgan, the fruit fly has been one of the favored model organisms for studying genetics. Amazingly, many of the genetic mechanisms that shape not only the anatomy and physiology but also the behavior of fruit flies are fundamentally similar to those for more complex animals, including human beings. And yet, even the fruit fly shows a remarkable flexibility in its genetics that comes from the complexity of genetic causality. There are few cases where a single gene has a single function. Most genes are pleiotropic, in that they have more than one effect. And most genes are interactive, in that the action of each gene depends on its interactions with other genes, with other molecules inside and outside its cell, and with the external world generally. Moreover, the action of the gene may depend on the life history of its cell and of the individual organism in which it resides. Rather than acting through linear pathways, as is commonly depicted in textbooks, genes form complex networks. These networks of genes influence behavior only through networks of cellular mechanisms throughout the organism, including the neural networks of the nervous system. These highly integrated networks arranged in nested hierarchies--from genes to cells to tissues to nervous systems--give even a simple fruit fly an adaptive flexibility to respond to contingent events that cannot be predetermined by deterministic laws.

The causal complexity of gene action puts severe limits on the power of biotech for manipulating genes that influence complex traits. So, for example, while we hear a lot of talk these days about "designer babies," there is no reason to believe that we will ever be able to "design" babies if that means controlling complex behavioral traits like intelligence and personality. The complexity of gene networks make it difficult, if not impossible, to use biotech to alter our genes to enhance desirable traits without bringing about undesirable side effects. If we knock out or suppress one gene because it contributes to some undesirable effect, we might discover that the same gene has other effects that are desirable. Or we might discover that the undesirable effect really depends on so many genes interacting among themselves and with so many other factors, that controlling one gene gives us no control over that undesirable effect.

Identical (monozygotic) twins--who have the same genetic constitution--are often remarkably similar, not only in their physical appearance, but also in their emotional and intellectual character. Fraternal (dizygotic) twins--who share only about half their genes--are often quite different from one another. This surely shows the powerful influence of genes on the behavioral propensities of human beings. But still, even identical twins are not really identical. They differ in their character traits in ways that make them distinct persons, because subtle differences in their life-history development give them different traits. These differences start even in the uterus. Most identical twins share the same placenta. But about one-third develop in separate placentas. Those who had separate placentas seem to be less similar to one another than twins who shared a placenta.

Even conjoined twins--those whose bodies are attached--show clear differences in their personalities, even though they have shared virtually identical environments as well as identical genomes. The original "Siamese twins"--Eng and Chang Bunker--were born in Siam (now Thailand) in 1811. They were born joined at the chest by a band of flesh. After their death, an autopsy showed that they had shared liver tissue. They moved to the United States, became successful farmers in North Carolina, and married two sisters. The sisters lived in separate houses. Eng and Chang would divide each week between the two homes. They had 21 children between the two of them. The brothers often fought with one another because their personalities were so different. Eng was quiet, amiable, and a teetotaler. Chang was aggressive, irritable, and inclined to alcoholism. In other words, they were individuals.

The individual uniqueness of living beings--even with individuals having the same genome--denies the popular idea that cloning produces duplicates. One motivation for cloning might be to preserve a loved one that is going to die. But this motivation is misguided because the clone would not really be identical to its progenitor. For example, pet owners might want to preserve their favorite pets by cloning them, but they would discover that the clones were not really replicas of their beloved animal. A company--Genetic Savings and Clone--was set up to sell cloning services to pet owners. They attracted great publicity a few years ago when they announced that they had cloned a cat that they named "Copy Cat." But this turned into a public relations flop when the pictures were widely published around the world. They had cloned a calico cat, and calicos have varying patterns of coloration that depend not just on genes but also on environmental cues in the mother cat's womb. As a result, "Copy Cat" did not look at all like the cat from which she was cloned. The scientists who did this work at Texas A & M University reported: "As with other genetically identical animals with multicolored coats, the cloned kitten's color patterning is not exactly the same as that of the nuclear donor--this is because the pattern of pigmentation in multicolored animals is the result not only of genetic factors but also of developmental factors that are not controlled by genotype." But that suggests that the excitement about cloning as a way of duplicating animals and humans is based on the false idea that identical genes produce identical creatures.