I just finished Paleofantasy, by the biologist Marlene Zuk; it’s largely a response to notions that we made a wrong turn with agriculture and cities, and should head back to the savanna, or perhaps the trees.
The main objection is that attempts to come up with a “paleo” diet, or exercise regimen, or childrearing method, or sex roles, are generally bullshit: highly speculative at best, completely made up at worst. More specifically:
- We aren’t cavemen, because we haven’t stopped evolving. Genetic changes like widespread lactose tolerance, or the adaptation of Tibetans to high altitudes, have occurred in historical times. Adaptation to disease happens even quicker. It’s just not true that the 10,000 years since the evolution of agriculture is too soon to adapt to our changed diet.
- The idea that early hominins were perfectly adapted to their environment, with everyone who came after being disastrously out of place, is a misunderstanding of evolution. Evolution is not goal-directed, and animals are never perfect. They’re always a genetic mish-mash, just good enough to have survived, always subject to tradeoffs and sudden environmental changes.
- We just don’t know exactly how early hominins ate and lived. The fossil record is scanty; our ape relatives live in very different ways; modern hunter-gatherers are themselves varied, and not necessarily representative of their ancestors.
- One thing we do know: they lived in a wide variety of habitats and climates, from African savannas to Mediterranean shores to Ice Age caves. They didn’t all have the same diets, or tools, or cultures; there was no single paleo lifestyle.
- Some of the specific ideas of paleo enthusiasts are almost certainly wrong. E.g. there’s good evidence that Neanderthals were grinding grain 30,000 years ago. A high-meat diet may only have become possible with the invention of ranged weapons, at about the same time. Some paleo fans claim that early hominins rarely ran; in fact one of the things humans are extremely good at is long-distance endurance running… we can run most animals down, including deer and horses.
(In case you didn’t get the memo, humans and their non-ape ancestors are now grouped together as hominins; the older term hominid now covers the chimps, bonobos, and orangutans as well.)
If you like a knock-out blow, Zuk rarely provides one– the usual problem isn’t that paleo fantasies are contradicted by science, but that they’re poorly supported. However, Zuk reviews the wide range of evidence that’s becoming available, from DNA analysis to ongoing evolutionary studies to finding food traces in Neanderthal teeth.
Another recent read, Chip Walter’s Last Ape Standing, is even more of a buzzkill. He presents life on the savanna as difficult: scant resources and plenty of competition. Some human features such as neoteny may be an adaptation to bad times– our infants are born prematurely, with a rapidly expanding brain, and thus can more quickly adapt to new or changed conditions. There’s also evidence that our species passed through a genetic bottleneck– compared with other species, we’re remarkably uniform, which could have happened if our total numbers dropped to 10,000 or so. The ancestral environment might not have been all that idyllic.
None of this, of course, means that you should stay on the couch, or eat loads of donuts and fries. We definitely have an unhealthy lifestyle; but the solution is to get more active, not to get more Australopithecine.