A new study indicates that a diet with adequate amount of fruits may lead to larger and more compound brains in primates.
The researchers conducted the study with more than 140 species of primates and examined the size of their brain, based on the diet. Monkeys, apes, lorises, and lemurs were some of the primates that were studied.
The team found that species, which primarily consumed a fruit-filled diet possessed 25 percent more brain tissues, when compared to animals consuming mostly leaves in their diet. This was observed even if the primates were relatively smaller in size than other species.
The researchers gave the example of howler and spider monkeys to validate their assertions. Both monkeys inhabit the South American rain forests and usually live in groups of 10.
The contrast between the two is quite evident as the howler monkeys relax and eat the leaves of the trumpet tree all day long. On the other hand, the spider monkeys are quite active and move around in small groups, foraging ripe morsels and passion fruits everyday just after sunrise. Therefore, even though both the primate species live in the same environment and share the same social background, spider monkeys possess bigger brains than howler monkeys.
Why Fruit-Eater Primates Have Bigger Brains
Fruits vary from season to season. Therefore, primates need strength and skill to find a way to gather the fruits the current season has to offer. Smarter and sharper monkeys are more skilled in this regard and get rewarded with nutrition from the fruits.
"If you are foraging on harder-to-access food, like fruit instead of leaves, then you need to have all the cognitive strategies to deal with that," says Alex DeCasien, lead author on the study.
DeCasien added that finding seasonal fruit tucked away in the nooks and crannies of trees is much more complicated than simply "grabbing a leaf and eating it."
Other Findings Of The Study
The study also found that apes and monkeys consuming animal proteins possess moderately larger brains, when compared to those consuming leaves. The researchers believe that primates require more brain power to pursue and eat things such as birds, frogs, and insects when compared to the leaf eaters.
However, DeCasien and her team found that animal eating primates possess smaller brains than fruit consuming primates.
Contrasting Previous Studies
Previous studies have revealed that large primate groups having very intricate social structures have larger brains. Scientists even used the finding — known as social brain hypothesis — to describe why humans, and some other primates like bonobos and chimpanzees, have relatively bigger brains than the rest of the primate species.
To justify the contrasting studies, DeCasien said that possibly diet and social structure are equally responsible for bigger brains.
The study has been published in Nature Ecology & Evolution.
