杏吧原创

THE shameful history of scientific racism in the 20th century is well known. For most of the first half of the century, fashionable genetic theories were quickly reflected in public policies 鈥� from compulsory sterilisations in the US to the Nazi death camps. Yet horrifying as the stories are, they remain historical accounts. It is not immediately obvious what they can tell us about the connections, if any, between contemporary molecular genetics and contemporary racism.

Human Biodiversity is one of the first books to rise to this challenge. Its author, Jonathan Marks, is associate professor of anthropology at Yale University, but he is also a biologist. Unlike many academics in the 鈥渉uman鈥� or 鈥渟ocial鈥� sciences, he understands what modern genetics is all about. This makes him able to explain and to mount a critique of what science today is saying about the biological basis of 鈥渞ace鈥� 鈥� in other words, about human genetic diversity. His clear and engaging writing makes this an altogether excellent book.

Marks uses a combination of history and biology to show that conventional notions of human 鈥渞aces鈥�, as well as the scientific theories current earlier this century, are and were intellectually bankrupt: modern molecular genetics has established that genetic profiles cannot divide humanity into any definitive types. There are no genetic markers for 鈥渞ace鈥� or 鈥渆thnicity鈥�: even the few genes apparently found only among 鈥淎fricans鈥� or 鈥淛ews鈥� or 鈥淐hinese鈥�, for instance, are by no means possessed by all the individuals designated to such groups. This intermingling of genes so characteristic of our species is the result of years of travelling and trading, migration and pilgrimage, invasion and conquest. Salman Rushdie鈥檚 description of himself as 鈥渁 bastard child of history鈥� applies equally to us all.

But this is not the end of the story. For, as Marks describes, contemporary genetics has not yet entirely abandoned the attempt to catalogue humanity along genetic lines. Instead of concentrating on the biologically more meaningful task of attempting to understand the microevolutionary processes that have created the rich genetic diversity within groups, 鈥渕olecular anthropologists鈥� still hanker after global explanations. They continue to seek descriptions of 鈥渞acial types鈥�, now conceptualised as genetic variation between populations. But this is to ask the wrong question, says Marks.

In a nutshell; Marks contests the direction of contemporary molecular anthropology, which is now closely aligned with the Human Genome Project in the US. He argues that current plans to reconstruct the history of human genes by sampling the DNA of exotic tribespeople throughout the world is fundamentally misguided. Resting on a tacit belief in genetically 鈥減ure鈥� races, this 鈥淗uman Genome Diversity Project鈥� is essentially old scientific racism dressed in new clothes, Marks claims.

The new scheme to chart the 鈥渉istory and geography of human genes鈥� through DNA analysis of far-flung 鈥減rimitive鈥� peoples rests on the mistaken assumption that such exotics do not have a history, says Marks. Yet other cultures are not 鈥渇rozen in time鈥� and are rarely 鈥渃ompletely isolated鈥�. Genetic intermingling 鈥� or 鈥渁dmixture鈥� in the crypto-racist jargon 鈥� is not, as some geneticists suppose, 鈥渓argely a recent nuisance鈥�, says Marks. 鈥淭hus the San peoples of South Africa, targeted at the top of the Human Genome Diversity Project鈥檚 list of isolated and unmixed populations, are neither.鈥�

Geneticists have made this error many times before, says Marks. In the 1950s, for instance, scientists persistently proclaimed the genetic 鈥減urity鈥� of the Navajos of North America, despite ethnohistorical evidence of extensive intermarriage with other Native American tribes. Today鈥檚 molecular anthropologists want to use genetic data to create an evolutionary tree of human populations, and various rival versions have already been produced.

Indeed, the task is not especially taxing. 鈥淥ne can always get genetic data and a tree from them,鈥� says Marks. The trouble is, 鈥渢he meaning of the tree may be elusive鈥�. For instance, 鈥渙ne can ask, after all, whether Cambodians are more closely related to Laotians or to Thais, but the forces that shaped the gene pool of Southeast Asia were operating long before the sociopolitical boundaries were erected, and independently of them鈥�. So it makes little sense to regard these arbitrary national divisions as transcendent biological entities. 鈥淚t is almost as misleading as asking whether lawyers are more closely related to architects or to accountants,鈥� says Marks.

The Human Genome Diversity Project will never 鈥渞esolve for us the nature of the large-scale relationships among populations鈥�, Marks argues, simply because the genetic diversity it documents springs largely from the messy and convoluted histories of continuously intermingling populations.

The long search for a science of genetic 鈥減urity鈥� throughout much of the 19th and 20th centuries has inadvertently demonstrated that the very idea of 鈥渞ace鈥� is a biological nonsense. Today鈥檚 reincarnation of that quest looks set to show even more convincingly that genes are no substitute for history. Human Biodiversity is an important book that deserves a wide readership.