Geneticist Luca Cavalli-Sforza says there is no scientific basis for race. Now his latest project has been attacked for bigotry. Ayala Ochert reports.
US President Bill Clinton was full of praise recently for the Anglo-American team of scientists who completed the first working draft of the human genome. In his congratulatory speech, he said: "One of the great truths to emergeI is that in genetic terms, all human beings, regardless of race, are more than 99.9 per cent the same."
Ironically, that finding came not from the Human Genome Project - the publicly funded group sequencing the genome - but from the work of geneticist Luca Cavalli-Sforza, who has tried in vain to persuade the project's funders that the differences between people's genetic make-up are worth exploring.
For the genome that the publicly funded project has sequenced is made up of the genes of only ten people. Celera Genomics, the private company that has been simultaneously sequencing the human genome, has used the genetic material of even fewer people - just five. "We have sequenced the genome of three females and two males, who have identified themselves as Hispanic, Asian, Caucasian or African-American. We did this to help illustrate that the concept of race has no genetic or scientific basis," says Celera's chief executive officer, Craig Venter.
Now Cavalli-Sforza, professor emeritus of genetics at Stanford University, is pushing for a Human Genome Diversity Project that would examine the genetic differences between all the peoples of the world. It is an ambitious plan that has encountered strong opposition. More upsetting to a man whose life's work has been opposing racism, the project has attracted charges of bigotry and colonialism.
Cavalli-Sforza founded the field of "genetic geography" 50 years ago, while at Italy's University of Pavia (he moved to Stanford in 1971). Much of his work is summed up in his book The History and Geography of Human Genes, which first set out the argument that there is no scientific, genetic basis for race. Cavalli-Sforza reached that conclusion after tracing the variation in more than 100 genes in people living in groups across the globe.
"External differences between people (skin colour, height and so on) suggest that there are 'pure' races, but in fact pure races do not exist. There are (genetic) differences between groups of people, but they're extremely gradual," he says. Surface differences, he concludes, are just that - surface. Traits such as skin colour or facial features are strongly shaped by climate and are governed by a very small number of genes. But the rest of our genes tell a different story - if you compare most genes across groups of people there is far less variation. "Those differences that we can see are a misleading sample of the differences that actually exist," Cavalli-Sforza says.
Because the differences between people in any one group are much greater than the average differences between groups, Cavalli-Sforza considers the concept of race to be meaningless. In fact, the traditionally "racial", climate-sensitive features are sometimes at odds with the story the rest of our genes tells us about people's origins. While Australian Aborigines superficially resemble Africans, their genes show that they are more closely related to Asians - not surprising when you consider that their ancestors had to cross Asia to reach Australia.
In The History and Geography of Human Genes, Cavalli-Sforza tells the history of humankind from its beginning in East Africa 100,000 years ago. About 60,000 years ago, some crossed into the Middle East, moving from there throughout Asia. Modern humans first reached the shores of Australia about 40,000 years ago, at the same time that others entered Europe. Isolated by oceans on both sides, America was the last continent to be populated, somewhere between 15,000 to 30,000 years ago.
Cavalli-Sforza is prepared to use any tool in the study of human history, not only genetics but also archaeology and linguistics. He describes the approach in his forthcoming book, Genes, Peoples, and Languages, which will be published in Britain in the autumn. Sometimes, he writes, genetics can answer tricky questions. In the early 1970s, archaeologists knew that agriculture first emerged in the so-called Fertile Crescent, travelling gradually from there to the rest of the world. But it was impossible to say if it was the idea of farming or the farmers themselves that had spread. Using statistics techniques, Cavalli-Sforza produced a map of human genes that matched the spread of agriculture, demonstrating that it was the farmers themselves who had moved.
The History and Geography of Human Genes was the summary of a life's work, but once complete, and at a time when most scientists would be planning their retirement, Cavalli-Sforza came up with his most far-reaching plan yet - the Human Genome Diversity Project. Early genetic studies relied on indirect markers, such as blood groups, to track genes, but he thought it was time to take things up a notch and use the genetic sequences themselves. He and his colleagues have already begun mapping the Y-chromosome, which is passed from father to son.
But the project - despite Cavalli-Sforza's anti-racist credentials - has provoked a storm of controversy. "In the political world, rationality is not a rule," he says wearily. Native American groups are among the most vociferous critics. Given the history of western interest in first their land, then their bones, they are understandably suspicious of scientists seeking to collect and store samples of their genetic material. A statement released a few years ago by a coalition of 17 different groups said: "In the long history of human destruction that has accompanied western colonisation, we have come to realise that the agenda of non-indigenous forces has been to appropriate and manipulate the natural order for the purposes of profit, power and control."
Such reactions, says Cavalli-Sforza, are based on a misunderstanding of the project's goals, which he argues are explicitly non-commercial. He has said that the DNA his team collects will never be made available to scientists working for profit-making companies. The controversy has made it hard to secure funding, but with a database of 1,000 cell lines being established in Paris, things seem to be moving ahead regardless. "In my view, the HGDP is beginning now. This is an important chapter in the study of evolution," says Cavalli-Sforza.
Human Genome Diversity Project: