Monkeys, like humans, have an innate ability to spot snakes very quickly, and in a new study, scientists have discovered what the primate's key visual cue is when spotting these slithering predators, Science Alert writes..

Cognitive scientist Nobuyuki Kawai from Nagoya University in Japan conducted experiments with three Japanese macaques (Macaca fuscata), who had never before seen real reptiles or amphibians, but only pictures. The results, as expected, showed that animals instinctively responded faster to images of snakes compared to images of salamanders..

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At the second stage of the experiment, scientists changed images of salamanders in such a way that they were “dressed” in snake skin. The results indicate that the monkeys responded to the pictures as quickly as they did to the pictures of snakes.. According to Kawai, scaly skin is likely an important visual trigger..

Note that in previous experiments, scientists have already discovered that humans and primates are able to quickly recognize snakes, but scientists did not understand how exactly they do this. At the same time, the monkeys did not respond faster to salamanders, a species that also has an elongated body and tail.. Experts have also discovered that this instinct exists in both adults and children and is triggered only by the sight of snakes..

Scientists now believe that snake skin appears to be another visual cue that primates target when instinctively deciding whether something is dangerous.. Kawai and his team aren't sure, but they speculate that this may be because our primate ancestors probably evolved a visual system to recognize scales characteristic of snakes.. The team also believes their findings will improve our understanding of vision and brain evolution in animals, including humans..

Statistics show that snakes are one of the most dangerous predators on Earth today, both for animals and people.. Scientists have found that they are responsible for about 94,000 human deaths a year. For comparison, in 2023 there were only 14 fatal shark attacks on people..

The ability to spot snakes remains critical to us as a species - which explains why even babies as young as 7 months have brains that respond to snakes even if they have never seen the animal before.

According to Kawai and his colleagues, they plan to repeat the study in the future, this time in humans..

However, scientists believe there is good reason to believe that our brains are wired in the same way as those of our primate relatives. In fact, snake skin appears to be a red flag for all primates, including humans.

Incidentally, these results are consistent with the snake detection theory, which posits that snakes were a strong selective pressure favoring changes in the primate visual system that allow them to detect snakes faster or more reliably.

Previously, Focus wrote that scientists filmed how the two largest snakes in the world hunt each other.