Steven Rose: The concept of race is biologically meaningless

From a public lecture given at Gresham College in the City of London, by its Professor of Physic, a leading geneticist

Discrimination and racism require real or imagined difference – from clothes and patterns of worship to skin colour and smell. But some differences are deemed important, others not, and what is important has differed at different times and in different societies.

Having naturally red hair is a biological difference, but not one that results in persecution. For discrimination, persecution, even genocide, to occur, difference has to be linked to a hierarchy of difference which can locate one group above another – men over women, the British over the "lesser breeds without the law" or whites over blacks. The categories are slippery (as in apartheid South Africa, with Japanese as honorary whites).

Superiority, since the 19th century and above all in modernity, has been defined in terms of civilisation (as in the current conflicts) or intelligence, as in the claims of whites as more intelligent than blacks. Nancy Stepan memorably described racism as a "scavenger ideology" which latched on to any type of theoretical justification to hand. But since the 19th century, one of its most powerful forms has been scientific or biological racism – the claim that innate (read "genetic") biological differences underlay racial differences.

Following 1945, a major attempt to refute such biological racism was made by the newly formed Unesco with a series of statements denying racial differences in intelligence, culture or creativity. Initially, the text was drafted by US cultural anthropologists, but biologists and geneticists came to support a modified version of the statement.

The Unesco statement, that we were all one human race, became the hallmark of humane liberal biological and social sciences, yet despite this there was still immense racism in everyday life. It was only the rise of the civil rights movement in the 1960s, not the Unesco statement, which stopped the lynchings, those "strange fruit on Southern trees" of which Billie Holliday sang so bitterly.

In popular culture, race was biologically defined as something you could see with your eyes. Whatever the geneticists might say – about there being often more in common between Americans of different skin colour but who shared a common genetic ancestry – cut rather little ice in the popular perception of race and therefore in the construction of US racism. In a cultural and political attempt to change this, the civil rights movement instead celebrated black difference: "Black is beautiful" was the new claim.

Science was not silent at the time of this fierce cultural and political struggle. The psychologist Arthur Jensen intervened, claiming, in 1969, the white superiority in intelligence over blacks. Similar debates took place in Britain with the psychologist Hans Eysenck. And later, from 1975, the emergence of sociobiology was seized upon by racist groups such as the National Front in Britain with the claim that "race and racism are in our selfish genes".

Population genetics has made immense advances in the half century since the Unesco statement. Biologists define "race" as a group or population differing in gene frequency from that of others in the same species. Such differences usually occur as a result of some type of geographic barrier limiting interbreeding, so that the two otherwise similar genetic populations begin to drift apart.

Thus there are distinct "races" of fruit flies – separated perhaps by mountainous or desert conditions. However, with very limited exceptions there are no such separated groups within the human population, and those that do occur do not map on to what are in conventional speech regarded as separate "races".

The consensus view among population geneticists and biological anthropologists is that the concept of "race" to indicate analytically distinct subgroups of the human race is biologically meaningless.