Alex DeCasien, a doctoral student in biological anthropology at New York University, recently published the results of a research study in Nature Ecology & Evolution, which found that the only factor that seemed to predict which species of primates had larger brains was whether their diets were primarily leaves or fruit,
Apparently the nutrients from leaves are locked up behind thick cell walls, and breaking down those barriers takes a lot of time and energy. Primates that eat leaves have to lie around for hours, with all their energy going toward digestion. Eating fruit, on the other hand, offers an animal a jolt of calories in an easy-to-digest package. In primates, the main beneficiary of all that newly available energy is the brain.
For the last 20 years, many scientists have argued that primates evolved bigger brains to live in bigger groups, an idea known as the “social brain hypothesis.”
Robin Dunbar, an evolutionary psychologist at the University of Oxford, and one of the authors of the social brain hypothesis, believes that better diets provided the fuel for the cognitive demands of managing increasingly complex social relationships from living in big groups. Dunbar notes that “Diet and sociality are not alternative explanations. They are complementary explanations.”
DeCasien, the doctoral student, sees another possibility. Eating fruit is more cognitively challenging than eating leaves, she says. A primate can find leaves basically anywhere, but it must remember where and when the best fruit is likely to grow. Fruit eaters also range over larger areas than leaf eaters, so they need top-notch navigation skills. And because some fruits may be hard to reach or protected by defenses like spines, primates also need problem solving skills or even tools. Evolution could have pushed fruit-eating primates to develop bigger brains to deal with these complex foraging conditions.
Richard Wrangham, a biological anthropologist at Harvard University, suspects that diet allowed, rather than drove, the evolution of big brains. But he’s convinced that diet is intimately tied to evolution, especially in a particular species of primate: humans.
While I am not overly concerned with what my ancestors ate, I think there are a couple of key ideas worth noting from these various points of view.
First, fruit is a good source of energy, and is more easily digested than leaves.
Second, leaves, such as spinach or lettuce, need to be broken down in order to access the nutrients. This digestive process requires energy.
If I put these two points together, it seems obvious what the perfect meal is:
a green smoothie.
I’ve talked about my daily green smoothie before, but here’s a quick rundown of what I put in it:
4 bananas, a heart of romaine lettuce, two large handfuls of spinach, a cup or so of strawberries, a cup or so of blueberries, a tablespoon of chia seed, and about 24 ounces of water
I blend it up, and there’s my breakfast.
Greens (leaves) are a critical part of any diet, but as noted above, one of the problems is the amount of energy required to break down such foods in order to get the nutrients. Putting the greens in a blender would seem to help a great deal in terms of breaking down those cell walls, making them much easier to digest.
I realize that writing about this study is a clear example of confirmation bias; I found a report that supports the way I do something, and I agree with it wholeheartedly.
And to make matters worse, but as a sign of full transparency, there is a quote in the story cited above from Wrangham, the biological anthropologist at Harvard University, in which he states, ““Cooking is what has taken the human lineage into a totally new realm,” he says, especially after we learned to cook meat. Wrngham is the author of a book titled, “Catching Fire: How Cooking Made Us Human”. Since it seems like the book may talk about eating meat, I have no plans to read it.
Like I said, confirmation bias at its best. Accept the data that supports your beliefs, and ignore data that may go against your beliefs.
Even if there were some benefits to eating meat, at this point, I have no desire to eat it.
I’m happy drinking my daily green smoothie; I need all the brain power I can get.