As epiphanies go, it was hallucinatory and a little disconcerting… I had been reading about human evolution for a couple of weeks, off and on, trying to wrap my mind around the sheer span of the time involved -- the hundreds of thousands of generations, running back (the current estimate goes) some four million years.
Arguably the story begins a million or two years earlier still, when some kind of proto-hominid emerged from the line that led to the chimpanzees and the bonobos. Humans share more than 99 percent of our DNA with them. We’ve done a lot with the upright posture and those opposable thumbs. The past two million years – the period between Australopithecus and Homo sapiens digitalis – looks positively frenzied by contrast with the usual pace of evolution. And yet we are still distant cousins of the chimps, despite our gift for exalting humankind as existing above nature, or outside it.
One day, while reading these facts and thinking these thoughts, I looked up to see that a very strange thing had happened to everyone around me. They were, all of them, tangibly and unmistakably primates. (Or rather, we were, since my own hand suddenly looked like a well-articulated variety of paw.)
It is one thing to understand evolution at a conceptual level; a fairly difficult thing. Experiencing the continuity between human beings and other species is something else altogether; something like a waking dream. And perhaps especially when seated in a bakery frequented by lawyers, lobbyists, and media people from nearby offices – wearing clothes and mostly fur-less, but still recognizable as mammals distantly akin to monkeys or apes, despite obvious differences in carriage and demeanor.
They (we, rather) were eating scones for breakfast, not chunks of raw antelope. But for a few dizzying moments there, this did not seem as large a difference as it ordinarily might.
Fair warning, then: Reading Travis Rayne Pickering’s Rough and Tumble: Aggression, Hunting, and Human Evolution (University of California Press) may well leave the bright line between nature and culture looking thinner and blurrier than usual. (Pickering is professor of anthropology at the University of Wisconsin at Madison.) I should also warn vegans against reading the book, unless they are in a particularly argumentative mood.
More on that in due course. First, a look at the perennial dispute that Pickering has joined about the source of mankind’s history of violence. One familiar bull-session or editorial-page option is to understand the penchant for violence as an intrinsic and inescapable human disposition, something for which we are genetically programmed, even. In support of this idea, one can cite Jane Goodall’s discovery about the chimps she observed in the wild. While sociable amongst themselves, members of one band were capable not just of killing outsiders but of teaming up to wipe out the young males in another group.
And remember, we share 99 percent of our DNA with the chimps. Case closed! Well, perhaps not, since we have the same margin of genetic overlap with the bonobos. “In general,” Pickering writes, “bonobos engage in sexual contact frequently and casually, in many cases to seemingly allay what could otherwise turn into aggressive interaction.” Besides making love, not war, bonobos in the wild “hunt less frequently than do wild chimpanzees.”
Bunch of hippies. Anyway, the old Hobbes vs. Rousseau dichotomy cannot be decided by consulting the genome -- and the fossil record suggests a more blended perspective on what human beings are and how we got here.
Pickering moves through the evidence and hypotheses about our prehistory with an eye on the disputes they have inspired among paleoarcheologists. Some of them sound quite nasty. (The disputes, that is, though a couple of the researchers also come across as petty and vicious.) I’ll sketch the author’s own conclusions here briefly, but what makes the book especially interesting is its tour of the disciplinary battlefield.
The brains and teeth of our distant ancestors give reason to think they were hunters: regular, successful hunters, at that. The brain consumes a lot of energy. Once proto-humans left the jungles to roam the savanna, their brains grew considerably and at a relatively rapid pace – something a steady diet of meat could only have helped. (And vice versa, since “acquiring meat presumably requires a smarter brain than does picking stationary nuts or grubbing for fixed roots.”)
Besides being available “in the form of large herds of grazing ungulates,” meat “is also soft and does not require that its consumers have a massive dental battery to break it down in the mouth.” Furthermore, the teeth in hominid fossils do not show the kinds and quantity of abrasion found in mammals that normally consume seeds and nuts (also sources of protein) in quantity.
Meat “adheres to bones, comes in large packages, and is stubbornly encased in hairy, elastic hides, so a cutting technology would have been most useful for a blunt-toothed [primate] that had begun to exploit this resource.” Pickering considers the fossil evidence not just of tools and weapons but of animal bones scored with knife-marks left by prehistoric butchers.
But our ancestors’ diet is only part of the story, since the author is less interested in what they ate than in how they developed the capacity to do so regularly. Hunting big game required more than spears and courage. In addition, Pickering stresses the need for emotional control: coolness, grace under pressure, the proper combination of strategy and stealth. He also suggests that the capacity to organize and manage aggression played a role within pre-human society, by obliging members to keep the group’s well-being in mind. An excessively greedy or violent leader might not last for long: the skills required to sneak up on and kill a buffalo could be turned to political uses.
Given how contentious the field seems to be (the title Rough and Tumble clearly refers to paleontologists as much as to prehistoric society) it will be interesting to see how Pickering’s colleagues respond to the book. As a layman, I can only say that it was fascinating and thought-provoking. And that, all things considered, I’d rather be a bonobo.
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