Dr Watson, in happier times

Nobel Laureate James Watson, co-discover of the double helical architecture of DNA, talks nonsense. There is no factual observational or experimental data of any measurable link between any human brain function ­ of which there are many ­ and a social construct called intelligence, of which there are, also, many.

This is what we know today: there is about a 2 per cent difference between modern human beings and our closest living ancestral relative the chimpanzee - using a crude DNA count. A portion of that DNA, we do not know how much of it, would explain the considerable differences in our brain size and specialisations, among other differences like stature.

The South African born Nobel Laureate Sydney Brenner once made a joke by asking what is left over if one subtracts the chimpanzee genome from the human one?

Genes that make it possible for language, he quipped and, he furthermore suggested, why not call them Chomsky genes ­ after the linguist Noam Chomsky.

We are the only survivors of the hominid (2 legged upright walking primates) line, probably because we had better strategies of finding food and defending ourselves against predators ­ both in variable climactic environments.

We are about 150,000 old as a species and we shared this planet with only two other far-distant cousins: Homo Floriensis (the hobbit man) and Homo Neanderthalensis.

You and I are descendents of a single hominid line called Homo Sapiens Sapiens or modern human beings. We are not the products of cross-breeding between hominid lines. There is no DNA or fossil evidence of successful offspring of a liaison say between archaic Homo Sapiens and Homo Neanderthalensis or Erectus or Floriensis or any other line. None, my friend.

We originated in East Africa: it is the only place that contains in its arid and fecund earth the least broken fossil record of our evolution and, established more recently, a genetic signature with unmistakeable links to our geographical origins. From our homeland there we travelled the world.

We lived in relatively small groups (of likely 150 individuals or so) until very recently as hunters and gatherers in a physical world that changed from warm to cold to warm to cold to warm and still changes in sometimes catastrophic flip-flops. There was a time when lived in mutual isolation for a very long time.

Our brain is the reason for our success. In his book Evolving Brains, Caltech¹s John Allman shows how the human brain was the instrument with Oits capacity to buffer environmental variation¹ (New York, Scientific American Library, 2000, p.194). It had evolved to a machine of complex neural networks weighing 1,460 grams by 21,000 years ago.

In his Quest for Consciousness, Caltech¹s neurobiologist Christof Koch provides a state of the art navigation of what we know and what we do not know about what is known as the neural correlates of consciousness or ncc¹s (Englewood, Roberts & Co, 2004). None of the little we know about the human brain suggests group (read racial) variation.

We do not know how many of our 26,000 or so genes are involved in the making of the specialised neural cells of the brain. The cells process information from our sensory and other organs and fire millions of instructions every day to both the involuntary and voluntary systems that make us grow, live for a while, and eventually die.

I am unaware of any hard evidence about human beings who, as a group, have a lesser ability to process information and fire instructions. Our brain mass has declined to 1302 grams because its functionality is in declining demand, but no group of human beings has seen a greater decline than others.

In our genome, we vary by about 0.01 per cent (counting DNA base pairs). Of the 0.01, a number of unknown genes create variation of how fast the brain processes information and fires responses. We do not know which genes they are.

We know even less about their distribution.

On the face of it, there is some variation in brain function between individuals and families. To speculate though that an entire group ­ Africa¹s people - to have lesser of a neural machinery betrays the core principles of the scientific method ­ where is the data?

It is ironic that the same institution ­ Cold Spring Harbour Laboratories ­ that was so central in the U.S. eugenics movement in the early 20th century is the same institution that suspended Watson from leading it today.