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May 11, 2004

The Real Eve, ups & downs

A few weeks ago, I read The Real Eve by Stephen Oppenheimer.

The skinny, this is an ambitious and broadly conceived work that has more conclusionary meat than methodological gristle. It is a contrast with the books of Bryan Sykes and Spencer Wells, who focus on their own particular research a great deal, and seem to pad the chapters with molecular biology primers that the lay reader would likely skip over in any case (for all of these books, see "Historical population genetics" on the sidebar of this site). But, there are some serious flaws with The Real Eve....

The "Prologue" presents his general conception of human evolution for the past few millions years. Though the heart of the book deals with the Out-of-Africa movements post-100,000 B.P., here he sets out a few axioms and premises, and stakes out his position in various palaeoanthroplogical debates.

Oppenheimer is rather clearly opposed to evolutionary psychologists who propose a "mental modularity." In particular, he sides (it seems to me) with neural connectionists on the issue of language, though he is honest enough to admit that they are a minority position in cognitive science. But here is how he characterizes Chomsky & co:

The other, at present dominant view of the origin of language is almost creationist in its denial of the process of language....

To use the term "creationist" to label the opposing camp when you are writing a book aimed toward laypersons who have an interest in human evolution and genetics seems a bit provocative, but I suppose one can justify it on literary grounds. But here is where Oppenheimer starts going off the deep-end:

The unique combination of lexical and syntactic features of a language such as French are the cultural possessions of the French community, and clearly do not result for any conceivable biological aspect of being French....

Readers who are really interested might want to read this paper (PDF) by Steven Pinker & Ray Jackendoff where they reply to Noam Chomsky's new position that syntactic recursion is the only unique aspect of human language. First, it seems ridiculous to assert that the "Chomskian" position (when he does not use the appellation "creationist," that is what Oppenheimer calls them) would imply that the French are biologically hard-wired to French syntax when Chomsky himself is making a fuss about the importance of recursion only. But even the more complex position of Pinker & co. that language is a specialized adaptation would never assert that French are hard-wired with French syntax. Rather, this seems a bizarre attempt to straw-man or caricature the position of the modularists.

Even here, one might assert that Oppenheimer doesn't mean his audience to take the above literally. But, what I find peculiar for a book that spends some time arguing that language is a cultural creation, an "invention" like tool-making, is that it neglects the recent research into FOXP2, the "language gene." This research predates the publication of Oppenheimer's book. FOXP2 does not show up in the index either. It is far easier to characterize your opponents as "Just-So" theorists if you neglect the fact that a new avenue of research might lead to the "smoking gun" that validates their hypothesis.

That is not to say that I accept that FOXP2 is the "smoking gun." I have cautioned against simplistic paradigms and their allure. But, Oppenheimer is clearly stacking the deck against them. Why?

Well, read the book, and one theme that crops up is the attempt to shift Europe out of its role as central to the evolution of modern humans. Oppenheimer asserts that modern humans were a "dancing, singing" people within Africa. This is to rebut the position that the "Great Leap Forward" occurred in Europe 50,000 years ago. This is why Oppenheimer argues against the "creationist" position on language, as the creation is hypothesized to have occurred in Europe. I won't go into the details of the whole model, but if Oppenheimer had waited a year, he might not have had to waste so much ink on refuting the idea that the "Great Leap Forward" occurred in Europe, as new research has muddied the waters of that theory. A quick citation of this research might have been enough to ease everyone's mind that Oppenheimer is justified in his attempts to overthrow Eurocentrism.

Though Oppenheimer has a fixation on de-centering Europe and asserting the fully modern humanity of Africans 100,000 years ago (and putting India in a place of prominence for Eurasian lineages), it is notable that he isn't one of those who seems uninterested in race. He has a whole section devoted to how "Mongoloids" came to be defined by their present phenotypic characteristics, going over points like climatic adaptation or sexual selection for paedomorphism. Oppenheimer's own wife is Chinese (like Spencer Wells' wife), so it is no surprise that he brings up this gem of human biodiversity:

The diversity of immune response held in each of us has limits, however, and depends partly on the particular bugs that our own community has met in the past.

Most of such genetic variation in resistance to disease operates through the adaptive immune system. Some populations appear to have a sounder immune response to certain diseases which may have afflicted their ancestors in the past. I came across an example when I was working in Hong Kong, where ethnic Chinese children almost never fall sick with meningoccal disease (meningitis and/or septicaemia). They usually develop detectable specific immunity to meningocci in the blood but, unlike Europeans and other non-Chinese groups, they completely avoid the disease and also do not act as carriers for the bug. In contrast, the commonest organism to find in Hong Kong Chinese with meningitis is the tuberculosis bacillus, which is extremely rare as a cause of meningitis in other developed populations. This implies that there are differences in the quality of aquired immunity to specific diseases between different modern populations.

Of course, this is peripheral to Oppenheimer's telling of the Out-of-Africa tale, which is the heart of the book, and I'll get to that next....

Posted by razib at 02:02 PM