Thanksgiving as parable for cultural evolution

Well, I have a moment again between incubations to consider the world outside these alabaster walls...

I was recently revisiting some of the work by Michael Pollan, an investigative journalist who has recently become an expert on the subject of the American Diet, industrial food production, and nutrition. In The Omnivore's Dilemma, Pollan revisits an old quandary regarding the decision that a omnivorous animal faces every time they "sit down" to dine. Particularly true for large mammals, omnivores have a range in diet that is unparalleled by most of their carnivorous or herbivorous cousins. This bounty of possible nibblets means that the gut of the animal must be more adaptable, able to process nutrition from a variety of different animal and plant sources. In exchange, the omnivore is granted a larger range in acceptable environments that they can live in and a somewhat relaxed sense of anxiety over acquiring enough calories since food is abundant all around them.

However, there is also a problem. The omnivore must somehow balance their intake of nutrients, as not all food sources are equally endowed. Unlike the koala or panda (of a few posts ago) who will eat only eucalyptus/bamboo (respectively) and are able to derive all of the proper nutrients from just that one source, most omnivores are less specialized and must somehow decide how to balance their diet in other ways. But how?!? Given the critical link between dietiary intake and the health of an individual, how are these choices made?

Okay. Now take a moment aside to consider your Thanksgiving table from this last Thursday - as well as the leftovers that are likely piled up in your refrigerator. Turkey, ham, potatoes, cornbread, cranberry, stuffing, beans, pumpkin pie... Yum! The food there comes from so many places... How is it that we decide to eat these foods and not others?

Pollan and others make the case that a large part of the brain needs to be dedicated to decisions related to diet. To recognize what is healthful and avoid the poisonous. Could it be that our impressive brain size owes its existence partly due to the wide range of foods that we can eat? In contrast, the koala has the smallest brain (about the size of a walnut) when compared to its less finicky cousin species. Furthermore, as we learn more about food and the nutrients that compose them, we often find that traditional diets across the world impose cultural standards that balance these inputs. For example, beans and rice are a common combo, and we have only recently been able to scientifically show that the amino acids contained in these two sources balance each other nicely.

Given the importance of food to all animals, it makes sense that culture should have many rules, customs, and taboos that are related to food. An interesting thought experiment is also to wonder how much role our diet had in our own evolution, biologically and culturally. A few studies have correlated a wider dietary availability and higher caloric intake with larger brain size. The brain is an energy-hungry organ, after all... Furthermore, in our species which has a long juvenile stage and a huge range of possible snacks, there is a much larger selective pressure to evolve additional methods to determine the correct foods to eat so that we can live to adulthood without eating that poison mushroom or contracting scurvy. Could culture be a large part of that link?

So the next time you sit down for a big meal on a holiday that is largely about giving thanks for the bounty of food that is available for us, maybe it also makes sense to thank your food itself as well. For without it, it is unlikely we'd ever have the brain power, or cultural advancement to be celebrating at all.