Brain Goes 'Hiss' on Spotting Snake; Special Region Dedicated to Detecting Serpents, Study

Snakes, those creepy, crawly creatures are the reason behind high-quality vision development in primates. A new study has found that the monkey brain has a region reserved to detect snakes.

The idea that primate vision has been partially shaped by snakes was first proposed by Lynne Isbell, professor of anthropology at the University of California, Davis in 2006.

Now, a team of researchers from Japan and Brazil have found that specific brain cells in rhesus macaque monkeys fire-up in the presence of snakes. This primitive part of the brain doesn't get activated in the presence of other creatures or objects, showing that the brain is hard-wired to respond to snakes.

"We're finding results consistent with the idea that snakes have exerted strong selective pressure on primates," Isbell said.

Surprisingly, more neurons were activated when the monkeys saw images of snakes than when they saw faces. According to Isbell, primates are known to social beings and so researchers expected that they'd have more brain cells dedicated to respond to faces.

Hisao Nishijo and Quan Van Le at Toyama University, Japan conducted the research. Nishijo and colleagues studied brain mechanisms associated with fear and other emotions. Many of their experiments involved inducing fear in monkeys using images of snakes.

In the present study, researchers exposed a group of monkeys to snakes. These monkeys were bred in captivity and had never seen a snake before the test. However, their brain still responded to snakes.

"The results show that the brain has special neural circuits to detect snakes, and this suggests that the neural circuits to detect snakes have been genetically encoded," Nishijo said in a news release.

"I don't see another way to explain the sensitivity of these neurons to snakes except through an evolutionary path," Isbell added.

The study is published in the journal Proceedings of the National Academy of Sciences.