Reduce cognitive inequality, eat meat

From Brain food: Clever eating by Sujata Gupta. The subheading is - Consumption of animals helped hominims to grow bigger brains. But in a world rich with food, how necessary is meat?

Around 6 million years ago, primates started moving from tropical forests into the savannahs. Unlike today, these prehistoric expanses were humid and probably provided a year-round supply of fruit and vegetables. But then, some 3 million years ago, the climate changed and the savannahs — along with their plentiful food supply — dried up.

Many mammals, including some primates, went extinct, but others adapted. Archaeologists working at sites in modern Ethiopia have discovered animal remains that date back almost 2.6 million years. The telltale cut marks on their bones are almost certainly signs of butchery1, says Manuel Domínguez-Rodrigo, a palaeoanthropologist at Complutense University in Madrid.

Only two types of primate survived the climate catastrophe, says Domínguez-Rodrigo. There was a “plant-processing machine on the one hand and a meat-eating machine on the other hand”, he says. “The meat-eating machine evolved a bigger brain.”

The meat-eating machine became us.

To build and maintain a more complex brain, our ancestors used ingredients found primarily in meat, including iron, zinc, vitamin B12 and fatty acids. Although plants contain many of the same nutrients, they occur in lower quantities and often in a form that humans cannot readily use. For instance, red meat is rich in iron derived from haemoglobin, which is more easily absorbed than the non-haem form found in beans and leafy greens. Furthermore, compounds known as phytates bind to the iron in plants and block its availability to the body. As a result, meat is a much richer dietary source of iron than any plant food (see 'Meat efficiency'). “You would need to eat a massive amount of spinach to equal a steak,” says Christopher Golden, an ecologist and epidemiologist at Harvard University in Cambridge, Massachusetts.

That matches the standard account which I have always read.

If these observations are true for our historical development, what are the implications today?

In the 1980s, researchers began to suspect that a lack of meat in some poor rural villages was contributing to a spectrum of childhood problems, including short stature, weakened immunity, social difficulties and poor school performance. When researchers from five universities studied the effects of chronic malnourishment in Mexico, Kenya and Egypt, they found that children who consumed the greatest amount of meat and dairy products scored highest on physical, cognitive and behavioural tests, particularly in Kenya. But was the absence of meat really to blame? What the researchers needed was a controlled study.

With a question, you do a study:

So Neumann began a trial in Kenya. Her team selected 12 schools with children aged 6 to 14, and gave some of the children midmorning snacks. Schools were divided into four groups: the control group was not given a snack, whereas the other three received variations on githeri, a traditional porridge that consists of maize (corn), beans and greens. One group received a basic version, the second received the basic githeri with a glass of milk, and the third had meat added; all githeri were balanced to contain the same amount of calories. The study continued for more than 2 years and spanned 2 cohorts, the first with 525 students and the second with 375. The students' physical health and classroom performance were measured every three or six months. Compared with the other groups, students in the meat group had greater muscle mass and fewer health problems, and even showed greater leadership in the playground. Cognitive performance was stronger, too: the meat group outperformed other groups in maths and language subjects.

Very interesting, though I do wish they would provide the effect sizes. Cognitive performance was 1% stronger, 5%, 10%?