Relative to other mammals, primates, especially humans, have large brains and scientists have proposed various explanations for the phenomenon. A popular and prevalent one is the "social brain hypothesis," which ascribes the brain size growth to the complexity of social interactions among primates. But research published Monday questions that hypothesis and puts forth its own factor responsible for the big brains in primates: their diet. Put simply, the social brain hypothesis posits that the pressure to maintain social relations among large, complex groups was the primary factor in the evolution of the large brain in humans. However, studies looking at different aspects of social interactions have thrown up mixed results, prompting some researchers from New York University (NYU) to take a different approach.
In the hope of understanding how humans developed their large brains, researchers have turned to our primate relatives. A new study suggests that primates and humans have bigger brains as a result of the search for food rather than because they developed in social societies. These results call into question'the social brain hypothesis,' which suggested that humans are big-brained due to factors associated with sociality. The researchers examined more than 140 species of primate. They found that species that exist solely on fruit or a mixture of fruit and leaves were found to have larger larger brains than exclusively leaf eaters.
PARIS – Humans likely developed large and powerful brains, researchers said Monday, with the help of what is today the simplest of snacks: fruit. Eating fruit was a key step up from the most basic of foodstuffs, such as leaves, and provided the energy needed to grow bulkier brains, the scientists argued. "That's how we got these crazy huge brains," said the study's corresponding author, Alex Decasien, a researcher at New York University. "We have blown up the quality of our food that we are eating." The study published in Nature Ecology & Evolution looked at the staple foods of over 140 species of primates, and assumed their diets haven't changed much over the course of recent evolution.