- Fear of Snakes May Have Compelled Pre-Human Adaptations - Image Leofleck
Snakes are one of the most ancient of human nemeses, with most people, as well as their primate relatives, having what appears to be an instinctual terror of the slithering snakes.
This is innate fear of snakes is likely a result of the fact that snakes were among the first primate predators to evolve; the legless reptiles were already established when the first mammals came on the scene about 100 million years ago. And according to a theory put forward by anthropologist Lynne Isbell, the long history between snakes and pre-human primates may account for certain adaptations in pre-humans' evolutionary lineage, such as larger brains and three-dimensional color vision.
Snakes vs. Early Mammals
Since snakes were the top predators of early mammals for a very long time — other predators such as eagles and big cats evolved much later — many creatures over time developed adaptations to help them avoid becoming prey. Some mammals evolved the ability to detect snakes through smell, while later ones developed immunity to snake venoms.
Early Primate Adaptations
According to Isbell, primates took a slightly different route, possibly due to the high fructose diet they were ingesting, which would have allowed significant brain changes in the areas associated with vision. Though it had long been conjectured that primates' forward-facing eyes (which confer superior vision in three dimensions) and improved discernment of color and detail evolved as a result of food location — with better vision required to distinguish different types of fruit, leaves and insects — Isbell argues that snake avoidance was likely a more compelling reason for these particular adaptations.
For example, being able to see detail and color at close range might have been very useful in avoiding being attacked by snakes, since unlike other predators, the compact reptiles are difficult to see at a distance. Additionally, Isbell points out that pre-humans, once seeing the snakes close up, would have had time to get away.
Venom Arms Race
Further, the adaptations might have gone the other direction as well. The snakes that lived at the same time as early primates were similar to modern boa constrictors, killing prey through suffocation. Perhaps as primates became better and better at detecting snakes with their superior vision, snakes had to evolve new methods of attacking prey, namely by using venom. In this way, the long and tangled relationship between snakes and pre-humans may have caused massive changes in both lineages.
Source
- Than, Ker. "Fear of Snakes Drove Pre-Human Evolution." LiveScience. 20 July 2006. Web. 29 June 2011.
Jenny Ashford - Jenny Ashford is a writer and graphic artist from central Florida. Her main area of interest in her Suite 101 articles is science, with a ...
