Saturday, October 07, 2006

Luskin Goes Ape Again

I see that Casey Luskin is once again "going ape", over the new issue of Time magazine, which shows a clever chimp/human hybrid face and which contains a very good article on the nature of the similarities (and differences) between humans and chimpanzees. However, once again, Luskin takes a very complex issue, picks a couple of pieces out of context, throws in a couple of quotes (also out of context) and then proceeds to explain away the silly notions of those anthropologists who don't know near as much about anthropology as Luskin the lawyer does. Luskin starts with the following:

Though the cover graphic (below) shows half-human, half-chimp iconography, University of North Carolina, Charlotte anthropologist Jonathan Marks warns us against "exhibit[ing] the same old fallacies: ... humanizing apes and ape-ifying humans" (What It Means to be 98% Chimpanzee, pg. xv [2002]). The cover-graphic commits both fallacies

What Luskin is implying to the casual, uninitiated reader (in excellent lawyer obfuscation, by the way) is that a professional molecular anthropologist, Jonathan Marks, does not accept that humans are related to chimpanzees, particularly evolutionarily. I happen to have had the pleasure of talking with Jonathan Marks on a number of occasions at both UC Davis and UW Madison (casual conversations, granted) and read his wonderful book. Marks is indeed concerned, and justifiably so, that too many scientists and science popularizers use this figure to draw unwarranted conclusions about behavior and variation between Homo and Pan. There are immense differences between the two genera. In a great review of Marks' book, Andrew Petto gets to the heart of Marks' thesis:

However, in another sense, the widespread use of this figure is misleading, Marks argues, because its apparent precision generates a false sense of scientific certainty - not so much in the great genetic similarity that it confirms between closely related species, but in the inference that this figure somehow "explains" things. What things could it explain? Suggestions range from promiscuity to aggression to homosexuality to any of a wide variety of interesting conditions that have so far only the most tenuous connection to specific sequences of DNA contained in the individuals who express them. There is a long, long chain of inference here, and for years Marks has consistently been calling scientists and science popularisers to task for their overgeneralizations of genetics research to address a wide variety of interesting social, legal, and technical issues: everything from racial studies, to animal rights, to creationism, to cultural hegemony and colonialism.

But make no mistake. There is a pattern of genetic relationships between humans and the great apes, chimpanzees in particular, that indicates not only that we are part and parcel of the non-human animal world, but that we are closer, genetically, to the chimpanzee than any other species on earth. Yes, humans are not like chimps in ways that are legion, and we must put this fact into context when discussing the implications of genetic information. And this is Marks' concern. Fair enough. But at the end of the argument, the facts still remain: humans are genetically more like chimps than any other species; humans are anatomically more like chimps than any other species, and despite the gulf, humans are still behaviorally more like chimps than any other species. And whether you like it or not there is a really important pattern that is consistent (and needs to be explained): among living organisms today the further distant you travel genetically from humans, the less anatomically similar to humans organisms become, and the less behaviorally similar to humans organisms become. And all of that can be quantified. There is only ONE idea that can account for that pattern: EVOLUTION.

Luskin would like Intelligent Design to serve as an alternative:

The article predictably touts the 98-99% genetic similarity statistic between humans and chimps, assuming that the similarity demonstrates common ancestry. Can common ancestry explain shared functional genetic similarities between humans and chimps? Sure, of course. But so can common design: designers regularly re-use parts that work when making similar blueprints. The article ignores that shared functional similarities between two organisms do not rule out design in favor of descent.

Let's assume for the sake of argument that Luskin has identified a valid hypothesis: shared functional genetic similarities are the result of design, not descent. How would you empirically test that assertion? What data specifically point to design and not descent. More importantly, would those data be useful in explaining issues as wide ranging as Hox genes, hominid skulls with varied cranial capacities, and pregnancy loss in wild babbons? Evolutionary theory is not just about hominid cranial capacity or the fact that we share 98% of our genes with chimpanzees. In fact, the revelation of that genetic relationship, for as much play as it gets in the media, really just confirmed what evolutionary biologists already knew. Again, from Petto's review of Marks:

This book is more than a long argument about the technical precision of various genetic and biochemical methods, however. It is about what we make of them. Long before the 98% figure burst forth into the public discourse, scientists and nonscientists alike were convinced that the African apes were our closest biological relatives. Every relevant discipline - comparative anatomy, palaeontology, embryology, psychology, behavioural ecology, comparative physiology, and so on - produced the same conclusion. In one sense, the molecular studies only confirmed what we already knew, as they should.

Luskin cites Marks in such a way to disparage the strength of this relationship. Since he apparently believes Marks makes his case, he should also feel comfortable heeding Marks' warnings about research. Once more from Petto's review:

Despite the apparent precision of scientific studies and the authority with which their results are reported, most violate what Marks calls "a simple rule of molecular anthropology: Genetic conclusions require genetic data" (p. 114, emphasis in the original).

Let me re-phrase that for Luskin and the Intelligent Design proponents:

Intelligent Design conclusions require Intelligent Design data.


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Anonymous said...

By evolution, humans are humanized animals. If you consider humanization of animals to be unethical, you are implying that the existence of humans is unethical. Are you advocating that all humans shold be killed for ethical reasons? If not, then stop claiming that humanization of animals is unethical! See Pure science Wiki.

Martin J Sallberg