According to anthropologist Lynne Isbell, it has been established that snakes have indeed a significant impact on primate evolution, since the legless reptiles constitute a major reason why monkeys and other primates (including humans) have developed a keen eyesight, which allows them to immediately recognize a snake when stumbling upon it.
As such, thanks to their acute sense of vision, monkeys and other primates remain on the constant look-out for snakes, and waste no time to raise an alarm when they spot one, whether it’s a giant constrictor that can ᴋɪʟʟ and ᴇᴀᴛ a primate if given the chance (pythons, anacondas…), or of the ᴠᴇɴᴏᴍᴏᴜs type (cobras, vipers…) – in fact, Isbell even claims that the monkeys that come into regular contact with ᴠᴇɴᴏᴍᴏᴜs snakes have evolved better vision than other species!
Studies have shown that even individuals that have never seen a snake can quickly learn to ꜰᴇᴀʀ the reptiles, associating them with ᴅᴇᴀᴛʜ via constriction or ᴠᴇɴᴏᴍ. But it’s still unclear whether their brain response shows they truly possess ᴏᴘʜɪᴅɪᴏᴘʜᴏʙɪᴀ (the abnormal ꜰᴇᴀʀ of snakes) or simply an innate ability to recognize a potentially ᴅᴀɴɢᴇʀᴏᴜs reptile.
Whether snakes were ᴇᴀᴛɪɴɢ primates, or simply delivering ʟᴇᴛʜᴀʟ ʙɪᴛᴇs, the evolutionary process to boost sᴜʀᴠɪᴠᴀʟ in their midst likely began tens of millions of years ago, said Professor Isbell.
Previous research has even shown that some primates, such as the Malagasy lemurs of Madagascar where there are no ᴠᴇɴᴏᴍᴏᴜs snakes, do not express ꜰᴇᴀʀ of them they way other apes and monkeys do.
“Snakes are largely responsible for the origin of primates. Vision is what separates primates from other mammals. A lot of the structures in our brain are devoted to vision,” said Professor Isbell, who wrote a book on the topic in 2009 called “The Fruit, the Tree, and the Serpent: Why We See So Well.”
“We have known that many species of monkeys either have an innate ꜰᴇᴀʀ of snakes or pick up a ꜰᴇᴀʀ of snakes very readily. This provides a probable mechanism. That has been a huge question in the literature.”