There is a mechanism in the brain of living organisms. Upon sensory perception of information that is "very likely to threaten life," the brain suppresses a large number of higher functions unrelated to life and death, focusing the neural network's computational resources on that event and swiftly entering the "fight or flight" stress response.
"Fear," along with "running away after fear" and "hasty attacks amidst panic," are applications of this mechanism.
And passive evolution often can't keep up with environmental changes—especially at the pace of human-driven modifications.
In the wilds of Earth, all snake species had become extinct. Many ordinary Benchmark Men would never encounter snakes in the wilderness, but this instinct could not be eradicated in just a few generations.
And to some extent, "Taksaka" capitalized on this point.
