Book Summary: The Book of Humans: A Brief History of Culture, Sex, War and the Evolution of Us
Author: Adam Rutherford
Tribalism is a very human characteristic, and while this is not to be discarded as irrelevant to biological evolution, tribes are transient, and perhaps a good example of a behaviour with which we distance ourselves from the shackles of natural selection. In non-human animals, there are almost no examples of seemingly pointless changes in behaviour that mirror fashion or fads.
Take the case of Julie. In 2007, she started a brand new trend, one that has endured. Julie was fifteen at the time, a young adult perhaps beginning to grow out of the whims of playful and capricious youth. That didn’t stop her from trying something new. One day, she decided that she was going to insert a blade of stiff grass in one of her ears, and that was going to be her thing. She continued her normal daily business, with the blade of grass sticking out of her ear. Her four-year-old son Jack noticed this new look his mother was sporting, and he decided to copy it. Kathy, five years younger than Julie, spent the most time hanging out with her out of all the other confrères in this group, and she adopted ear-grass soon afterwards. Val was next. Other close acquaintances followed suit, eight in total out of a gang comprising twelve members.
Julie was a chimpanzee. She died in 2012, but the trend she trail-blazed has persisted within her local social group and has spread to at least two other chimp populations nearby, with whom they occasionally overlap, but don’t really hang out with, in the Chimfunshi Wildlife Orphanage Trust, a sanctuary in north-west Zambia. The latest reports from the primatologists who study these chimps say that Kathy and Val still wear a single blade of stiff grass in one ear.
We observe many social behaviours in chimps that are recognisably similar to ours, many of which are discussed elsewhere in this book. This may be the only documented account of chimpanzees adopting what is described in the scientific literature as a ‘non-adaptive arbitrary tradition’. Or in other words: a fashion.
There are a few examples of other behaviours in which chimps copy other chimps for reasons that we do not understand. Tinka, an adult male chimpanzee living in the Budungo region of Uganda, has almost total paralysis in both hands, having caught them in one of the many snares that local hunters set for bush-pigs and small deer called duikers. His hands are locked in a hooked rigor with some slight movement in the left thumb, and none in the right, and they are barely functional. Tinka also has an apparent allergy, with patches of balding, rashy skin, possibly caused by mites, and almost certainly exacerbated by his inability to hand scratch or pick the mites from his body. He can’t do many of the normal and essential practices of daily chimp life, which have both biological and social functions, such as grooming. Instead, Tinka has developed his own head-scratching technique, which involves pulling a liana vine taut with his foot as it’s anchored on a branch, and rubbing his head against the vine, back and forth like a saw.
This is interesting as it stands. It shows a sophisticated ability to manipulate the environment and utilise your surroundings to create a necessary tool. Then again, monkeys, bears, cats and many other mammals scratch their backs up against trees, rocks or house furniture. What is much more interesting though is that once Tinka started to do this, many of his associates did too. Fully able-bodied chimpanzees copied his style, seven in total. All were younger chimps, five were female; twenty-one incidents of liana itch scratching were filmed. Tinka was present in only one of the observed scratching bouts. We cannot therefore say that the copycats were doing it as some lickspittle nod to a senior chimp. It just caught on.
These examples are few and far between. Perhaps they are outliers, freakish oddities that are not representative of the cognitive status of these chimps. But they are real. Perhaps Tinka’s method is a better way to scratch one’s head. The key thing is that they don’t appear to be adaptive behaviours, at least not in a direct way. It looks like these chimps are copying a style for no particular reason other than to be in with the in crowd.
With tools, with weapons, even with fashion, we have extended our abilities far beyond those of other animals. While we see some tool use, flashes of the violence that we indulge in, and the merest glimpse of aesthetic choices, the differences are stark. Our cognition and dexterity have given us the wherewithal to manufacture objects of such sophistication that we became obligate tool users, creatures who have been manipulating our environment for so long that we have been utterly dependent on technology for hundreds of thousands of years.