LEFT-leaning cartoonists delight in parading George Bush as a simpleton chimp in presidential clothing. Their mistake, it now seems, may be in singling him out for such satire. According to the latest analysis of our DNA, we are all, in the words of the scientists behind the study, 鈥渟lightly remodelled chimpanzee-like apes鈥� (see 鈥淧eople and chimps belong together on the family tree鈥�). In fact, say the researchers, chimps and bonobos are so very nearly identical to us at the level of DNA that they should be reclassified as belonging to the same happy taxonomical first family.
You could be forgiven for feeling a little bewildered. For years the routinely touted number for our genetic 鈥渃himpanzeeness鈥� was 98.5 per cent. Then molecular biologists revised the figure down to less than 95 per cent. Now it has shot up to its highest level yet: 99.4 per cent.
The confusion reflects the fact that there is no gold-standard method for comparing the DNA of different species. Search corresponding genes in humans and chimps for single-letter DNA base changes and you find very few of them: hence the 99.4 per cent figure. Search corresponding human and chimp chromosomes for 鈥渕issing鈥� or 鈥渆xtra鈥� chunks of DNA and you find rather more genetic difference, which led to the 95 per cent figure. It will take years of much closer analysis before we know which types of genetic difference 鈥� single letters versus chunks, or both 鈥� explain the physiological and intellectual differences between humans and chimps.
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In the meantime, what should we call our closest primate cousins? Renaming the chimpanzee Homo troglodytes might seem a convenient way to galvanise conservation efforts. But with the jury still out on how to make sense of genetic similarity, such a move would be vulnerable to the charge that it is ideologically motivated. Plus, suggesting that chimps should be protected because their genes make them honorary members of the human club sets a dangerous precedent for the vast majority of creatures whose genes are not sufficiently human-like to get in.
Or we could get rid of the exclusive hominid club altogether by declaring ourselves members of a new, enlarged pongid family. But what would the cartoonists draw then?
