‘What It Means to Be 98% Chimpanzee: Apes, People and Their Genes’, by Jonathan Marks. (University of California Press. Paperback)
Marks’s answer to the finding that humans share 98 percent of so of their DNA with chimps is that it doesn’t mean much more than we already knew and certainly not what some read into it. It confirms that millions of year ago (7 million is the generally accepted estimate) humans and chimps had a common ancestor. More generally, since all life-forms are built up of DNA, it confirms Darwin’s view that all those that exist and have existed on Earth evolved from a single original form. On the other hand, it does not mean that humans are 98 percent chimpanzee (any more than the fact that we share 35 percent of our DNA with daffodils means that we are 35 percent daffodil) and that therefore the study of chimpanzee behaviour is relevant to the study of human behaviour. As Marks puts it succinctly, “you can’t get at human nature from chimpanzees. They’re not human.” We are not naked apes, but clothed humans; which makes all the difference.
Marks goes for those who think that genes are the most important factor in human behaviour (the Social Darwinists and the eugenicists in the past and the behavioural geneticists, sociobiologists and evolutionary psychologists today), making the simple, but often ignored, point that we don’t actually know how any gene works. We know that genes produce proteins for the cells that constitute the body but not yet how this translates into a person’s physical attributes let alone (if it does) into any mental traits. What we know at the moment is that certain defects in certain genes result in certain abnormal conditions (such as cystic fibrosis), but not how a non-defective gene produces a normal condition.
This is why, Marks insists, when someone makes a claim to have discovered a gene for something, for instance homosexuality, they can’t just point to statistical correlations or even similar brain structures, they would need to produce a verifiable and verified causal explanation of precisely how the gene in question translates into the particular behaviour pattern. As he puts it, “what is widespread is not necessarily innate” and “genetic conclusions require genetic data”:
“The fact that something is consistently observed does not imply that it has a genetic cause. We know that. If you want to argue about science and about genetics, you need controlled data and genetic data.”
He warns modern geneticists about the dangers of making claims that go well beyond the existing (genetic) evidence, by pointing to the dominant view amongst geneticists in the 1920s which was racist and justified the forced sterilisation of “mental defectives” (not just in Nazi Germany but in America and even in Sweden). They were wrong and the practical consequences were disastrous. Seeing that we don’t yet know how normal genes translate into physical attributes, modern geneticists should, he suggests, show a little more humility before propagating their speculations about human behaviour being genetically determined as if it were an established scientific fact.
Marks is also good on the myth of race. “Race”, he says, “turns out to be an optical illusion”:
“[W]e can, of course, make comparisons between groups of people and study their differences. The problem is invariably what meaning to assign to those differences. If we know that there are gradients, not boundaries; that human variation is patterned locally, not transcontinentally; that the extremes are not the purest representatives of anything, but simply the most divergent; that populations are invariably mixed with their neighbors, and in the last half-millennium with people from far away; and that clustering populations into larger units is a cultural act that values some differences as important and submerges others – then race evaporates as a natural unit.”
We have to record, however, that in the last five of the book’s twelve chapters Marks embraces some strange positions, such as defending the right of a North American Indian tribe to veto research on a 9,000-year old skeleton found on their former tribal territory as this conflicted with their “spiritual” values (much as the Mediaeval Church had “spiritual” reasons for frowning on the dissection of human bodies). Similarly, he defends the refusal of certain indigenous people in other parts of the world to have their DNA recorded. Here, if it true, they may have a legitimate point about it being patented and used by others to make money, but this is a distortion due to the existence of capitalism. In principle, there is nothing wrong with recording the DNA of peoples who have been relatively isolated from the rest of humanity.
Adam Buick
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