Why Am I Not Surprised

National Geographic News

"In a sort of evolutionary arms race, primates kept improving their eyesight to help spot and avoid snakes as the snakes became more dangerous, suggests Lynne Isbell, a behavioral ecologist at the University of California, Davis. 'The initial change in primate [eyes] ... occurred when they had to deal with constricting snakes, probably about 90 million years ago,' Isbell said.
'That ended up with primates that have forward-facing eyes, whereas other mammals tend to have eyes on the sides of their heads.' Forward-facing eyes allow better depth perception.
When poisonous snakes evolved about 60 million years ago, primates further specialized their visual systems.
'That resulted in the anthropoid primates - which we are one of - which had better vision all around, compared to the earlier primates that only had to deal with constricting snakes,' Isbell said.
The study is published in the July issue of the Journal of Human Evolution. "