Not a Chimp: The hunt to find the genes that make us human is an exploration of why chimps and humans are far less similar than we have been led to believe. Genome mapping has revealed that the human and chimpanzee genetic codes differ by a mere 1.6%, but author Jeremy Taylor explains that the effects of seemingly small genetic difference are still vast. In the post below, he looks at cases of domesticated chimps turning on their owners and argues that humans must learn to keep chimpanzees at arms’ length, literally and intellectually.
Jeremy Taylor has been a popular science television producer since 1973, and has made a number of programmes informed by evolutionary theory, including two with Richard Dawkins. You can visit his blog here.
In the first chapter of Not A Chimp I tell the blood-thirsty and cautionary tale of how two male chimpanzees attacked a middle-aged American couple and savaged the husband to within an inch of his life. I wanted to highlight the strangely ambivalent world of chimpanzee-human relations which can turn on a sixpence from anthropomorphic domestic bliss to berserk savagery. Sadly, but not surprisingly, attacks on humans by chimpanzee pets are not rare. Earlier this year, a young chimp called Travis, who had lived happily and docilely at home with a Connecticut woman, suddenly showed his dark side and mauled her friend, terrified the neighbourhood, attacked a posse of policemen who had rushed to the scene, and was dispatched, Dirty Harry style, by an officer’s fire-arm. One minute you can be sitting peacefully with your simian chum, both sipping Budweisers while watching a baseball game on TV, the next minute he’s biting a neighbour’s fingers off and causing havoc.
There are over 200 chimpanzees kept as domestic pets – companions – in the United States, where their owners feel compelled to disregard the fact that chimps are immensely strong, emotionally labile, and potentially highly dangerous wild animals, in favour of the comfy tea-and-slippers notion that they are so like us humans in terms of genetics, behaviour and cognition, that they are, quite literally, one of the family. Not so long ago we were thought to have diverged from the line that led to chimps a massive 25 million years ago, and had since evolved unique cognitive powers that set us apart from them. Now we know that chimp and human ancestors diverged a mere 6 million years ago, and that, over many stretches of the DNA in our respective genomes, we appear to be almost 99% identical. Although hotly contested, a good number of cognitive psychologists contend that the mental lives of chimps and humans are also closer than we once thought, and that chimps can empathize, deceive and manipulate each other because, like us, they understand that other individuals have mental lives in which their actions are governed by beliefs, desires and knowledge – rather than acting like unconscious lumbering robots.
Our lay persons’ ability to anthropomorphize our pets – in this case chimps – plays into the hands of what I call the “chimps are us” industry where scientists who should know better accentuate the similarities and trivialize the differences between chimps and humans such that humans, as Jared Diamond so memorably dubbed us, have become perceived as the “third chimpanzee”. But these scientists are simply behind the times, reading from a genetic script festooned with cobwebs. Over the last 10 years or so, thanks to increasingly powerful means to investigate the genetic structure and DNA sequence, we now know that chimpanzee and human genomes are nowhere near as similar as we have been told; that there are crucial differences between the timing and rate at which near-identical genes work in humans and chimps, particularly in the brain; and that there are a host of exotic structural differences between chimp and human genomes, caused by copy number variation of genes, multiple duplications of enormous sections of DNA, insertions, inversions and deletion of genetic code, and many more mechanisms, all of which serve to reduce the similarity of chimp and human DNA.
I am not quite sure what the best explanation is for this persistent over-stressing of the similarity between us and chimpanzees, apart from a need to anchor us more firmly to the animal kingdom by abolishing the speciesism that has, in the past, held us apart, above, “better than” all the other great apes. Something unique. Perhaps this idea of cognitive uniqueness, an unbridgeable cognitive gap between us and chimps, sniffs too suspiciously, and dangerously, of religion – the perpetual assault on conventional evolutionary biology by creationists. We use science to close the ranks between us and the other great apes for fear that God will get a foot in between us and replace Darwinian origins with divine ones. Certainly, what similarity there is between us and chimps has been used to bolster our sense of affinity with them, the better to urge us to conserve them in a world in which their habitats are becoming rapidly decimated. Indeed, we are perilously close, in my opinion, to the philosophical insanity of widely using the concept of human rights to protect and conserve chimpanzees. Here the concepts of cognitive and genetic proximity are used to argue that chimps are “virtually human”, or even worse, that they are as human as little children or the feeble-minded. Though why we need to be persuaded to save chimps because they are nearly genetically identical to us, when we need no bidding through shared genetics to try to save the rainforest, the green-flowered Helleborine orchid or the Javan rhino, is beyond me.
Even if, over parts of our respective genomes, chimps and humans are 99% identical this does not mean that chimps are 99% human or alternatively that we are 99% chimp. We must learn to keep chimpanzees at arms’ length – literally and intellectually – while still being capable of thrilling to their complex social intelligence and using them as an essential scientific tool to find out how we evolved from something that very probably looked and behaved quite like them. Chimps are NOT us!