The sheer range of things that people consider edible is bewildering. So too the disagreements among people. Your mopane worms turn my stomach. My horsemeat lasagne is an affront to far more than your desire for truth in labelling. So are there any valid generalisations about human diets and appetites and how they came to be? Kristen J. Gremillion, a professor of anthropology at Ohio State University, thinks so. Biological evolution equipped us with the physical and biochemical machinery for processing some kinds of foods and not others. Social and cultural evolution then added layers of adaptability and flexibility. Of course there are differences in the apparatus, most famously perhaps the ability of adults to digest the lactose in milk, but the cultural differences are far more important and make us what we are: consumate omnivores.
Ancestral Appetites is by no means a comprehensive or exhaustive survey, but it is all the more readable and enjoyable for that. This is fine popular science, with none of the excesses that accompany other similar efforts to explore human diet. To begin with Gremillion takes a straightforward chronological approach, but rather than starting a little before the birth of agriculture she takes us right back to the golden age of hominins, as we must learn to call our ancestors who aren’t also ancestors of chimpanzees or gorillas. And she explains how researchers today know what our ancestors ate with much more accuracy than before thanks to vastly improved analytical tools. Things like the ratio of strontium to calcium in the bones, which reveals the balance between plants and meat in the diet, or the prevalence of 13C, an indicator of dryer, hotter conditions, or a much finer understanding of the patterns of tooth wear and tear caused by different foods.
Social evolution and the culture it enables act as a store for the trial and error discoveries societies make. Each generation does not have to repeat the mistakes of its parents, but because this behaviour is learned, it isn’t a trap either. We don’t need to learn afresh, but nor are we constrained to do only what our parents did. We can discover new things to eat, new ways to prepare them, new ways to nourish ourselves; this combination of tradition and innovation is one of the primary factors that enabled humans to spread out around the world. At some stage, of course, it also enabled some bright sparks to start on the road from cultivation to domestication and hunting to husbandry.
At this point Gremillion cleverly switches tack, abandoning chronology in order to examine hunger and abundance, flip sides of the same coin. I warmed to the idea of the social stomach. When we have enough, we feed others, especially if the food is difficult to store or defend. When we lack, we expect others to feed us. Sharing like this shades into the use of food as expressions of power and privilege, another behaviour that is surprisingly ancient. All in all, Ancestral Appetites powerfully conveys the continuity of human foodways. Each band of African hominins presumably shared the same basic diet. As their descendants fanned out across the world, tradition and innovation allowed them to adapt to almost all circumstances.
Does knowing what we used to eat shed any light on what we ought to eat? Gremillion agrees that the Paleolithic diet offers health benefits, but it is not the only set of choices to do so, and she sees growing “nostalgia for the Pleistocene” as further evidence that our history has provided us with the creativity and intelligence to optimize nutrition in many, many ways. Some of those choices, however, just don’t make sense, and Gremillion touches on Richard Wrangham’s idea that cooking made us human at least partly to debunk raw food enthusiasts:
“[B]esides ruling out many of the foods that taste buds delight in, a raw food diet eliminates the rewards of cooking as well as the drawbacks. Cooking caught on for a reason; not only is it easier on the teeth and jaws than the tearing and crushing of hard, fibrous and elastic materials, but it has the benefit of breaking down the compounds in food in ways that facilitate the extraction of nutrients.”
That’s Wrangham’s primary point; cooking increases efficiency of eating, and we have to be very well supplied willingly to give that up. Increasingly, though, we are very well supplied. Indeed, the evolutionary argument — that until yesterday it was all but impossible to eat too much fat, sugar or salt — probably explains why our ability to control our appetites for those things is so ill developed. That doesn’t mean we shouldn’t try, and Gremillion welcomes the fact that some of us do limit our intake as support for her basic thesis.
“Paradoxically, our flexibility as a species allows us the freedom to constrain ourselves as individuals in ways our ancestors would probably find incomprehensible.”
If the past is any guide, our ancestral appetites, filtered through biological and social evolution, will keep some of us well fed well into the future; so bring on the mopane worms.
Ancestral Appetites: food in prehistory, by Kristen J. Gremillion, was published by Cambridge University Press in 2011 (although I found out about it very recently).
Paperback £17.99 US$27.99 ISBN: 9780521727075
Hardback £50.00 US$88.00 ISBN: 9780521898423