How do monkeys recognise snakes so fast?

A Japanese researcher has found that a monkey’s ability to rapidly detect snakes is because of the presence of snake scales as a visual cue. The findings highlight an evolutionary adaptation of primates to identify snakes based on specific visual characteristics. In an experiment the researcher demonstrated that monkeys exhibited an immediate response to images of snakes but not to images of salamanders, implying a specific fear of snakes. On the basis of this observation, the researcher wondered what would happen if he edited the images of the salamanders to have snakeskin without changing anything else. When edited images of salamanders with snakeskin were shown to monkeys, they reacted to the altered images of the harmless creature equally fast, or even faster, than to the snake. The results are “consistent with the snake-detection theory that snakes were a strong selective pressure favouring modifications in the primate visual system that allow them to detect snakes more quickly or reliably. This strongly suggests that “primates’ snake detection depends on the snake-scale shapes, which are both snake-specific and common to all snakes”. Humans too react rapidly to snakes; infants as young as 8-14 months respond more rapidly to snake images than to say, flower, and snake pictures elicited specific neural responses in infants who are just 7-10 months old.