If you’re a fan of “paleo” diets, you might be in for some bad news: eating starchy foods was part of the reason human brains are so large. Meat-heavy diets have been around for years, but a recent trend has been to tie them to early human evolution, and argue that they are, therefore, better for us. The trend is largely based on science that suggests that eating meat, specifically cooked meat, was the key to developing larger brains, which in turn allowed us to develop language, civilization, and, my personal favorite, the internet.
However, according to a new study, while eating meat may have spurred brain development, eating carbohydrates is what allowed us to keep it going. The brain requires about 60% of the blood glucose that your body produces, and it’s much more efficient to give the brain what it wants by eating carbohydrates. Furthermore, low blood glucose levels during pregnancy and lactation can threaten the health of both mother and child. Starches, which are the principle source of carbohydrates, were readily available to early humans, and the development of cooking made digesting them much easier. And to top it all off, we developed salivary amylase genes to break down those carbohydrates. Our bodies, as they currently exist, evolved to eat both meat and carbohydrates, not one or the other. So why choose?
This new study gives us some important insight into the development of early humans. Since about 800,000 years ago, human brain size has been increasing, though obviously the most significant growth was earlier in the process. But that growth was facilitated by eating carbohydrates, which allowed for earlier brain development in fetuses, which in turn led to larger brains overall. The research also has implications for modern dieters as removing entire food groups from your diet, or even just severely reducing them, can have negative effects on your health. It’s important to think carefully about what we’re putting in our bodies—how it’s going to affect us, both in the short-term and the long-term.