Primates are known to have bigger brains when compared to other mammal species. However, science was unsure what caused this evolution. Now, a new study claims to have found an answer, namely their fruit diet.
Research on the matter was carried out by New York University researchers. They released their study results on Monday, March 27th. These were published in the Nature Ecology & Evolution journal. The paper is titled “Primate brain size is predicted by diet but not by sociality”.
Primate Brains, A Fruit Diet, Sociality, And How They Mix
Science advanced a number of theories which could theoretically explain the primates’ bigger brain size. One of the most prevalent and famous ones is the “social brain hypothesis”. This proposes as follows. The brain size increased as its bearers were faced with increasingly complex social interactions.
Nonetheless, this new research took a new approach to studying the problem. Instead of looking at the primates’ social structures, it looked at their diet. It did so as previous studies on the social matter revealed mixed results.
The current study involved an analysis of over 140 primate species from more actual evolutionary trees. This is a higher number than the one used in other, similar research on the matter. The research team also followed several factors that determined their sociality. For example, they monitored the species’ social systems, the size of their groups, and also their mating habits.
At the same time, the researchers also followed their diet. They did so by breaking the primates into 4 categories. These were the frugivores or the fruit diet species, and the folivores or those that eat leaves. Also, they included a category for species that eat both fruits and leaves, as well as one for meat consumers or omnivores.
A Fruit Diet May Have Led To A Bigger Brain Size
The research team found that primates with a fruit diet had significantly bigger brains. This applied when compared to all the other categories. For example, the fruit diet group presented 25 percent more brain tissue when compared to leaf diet species.
This remained consistent even as the team introduced control factors. These were the primates’ body size and also their phylogenic place. As it is, the researchers pointed out the following. The fruit diet in itself is not necessarily the cause behind the bigger brain. Instead, the cognitive process effort required by their diet may be the real reason behind the brain growth.
“Fruit is patchier in space and time in the environment, and the consumption of it often involves extraction from difficult-to-reach-places or protective skins.”
This is according to the study’s lead author, Alex DeCasian. He stated that taken together, these factors may account for a relatively higher brain flexibility in frugivorous species. To put it simply, their fruit diet may have required a “greater cognitive complexity”.
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