Why did humans and monkeys evolve to hate the color red?

Red is the color of anger and hatred, of imminent danger and deadly heat. Even the English language tells us that "seeing red" is a bad thing. And this aversion for red might go back to our earliest primate relatives.

With all due respect for people who consider red their favorite color, the overwhelming cultural cues when it comes to red is that it's the color of danger and should be avoided - driving for as little as thirty seconds should present you with a traffic light or stop sign that's ample reminder of that. Even our body seems to tell us that red is bad - just consider how people blush or redden when experiencing extreme, potentially harmful emotions.

New research at Dartmouth College seems to support the latter. Researchers tested some rhesus macaque monkeys to see which colors they preferred. They were presented with three human test subjects, each of whom was holding a banana. Each tester wore a different shirt and baseball hat - one combination was green, another was blue, and the last one was red. By and large, the monkeys took the bananas from the blue and green testers, almost completely avoiding the red one.

This is interesting because macaques are fairly similar to us in terms of how they interact with red. They have very similar eyesight to us, and they too blush when angry or excited. The experiment isn't perfect, as only male macaques were tested and the fact that they had to interact with humans instead of members of their own species may have presented a variable that we can't properly account for, but it's still a very intriguing result.

Assuming an aversion to red didn't evolve separately in humans and macaques, then it's a trait that goes back very far in our evolutionary history, to a time that we shared a common ancestor with Old World monkeys. That goes back 25 million years, to a time long before we diverged from closer evolutionary relatives like chimps, gorillas, orangutans, and gibbons.

So why would primates dislike red so much? It is the color of blushing, which is associated with potentially negative emotions, and so our sociability might bring with it an aversion for red-related emotions. Another possibility has to do with being able to know which fruits and plants are ripe and which are potentially toxic. But the simple answer is that we still don't know why we as a species seem to have such a problem with red.

The researchers close by suggesting that we should be more aware of the human aversion for red and its potential misuse for intimidation, even going so far as to suggest that sports teams should not wear red uniforms because it "may unfairly influence people." However, I have the sneaking suspicion that that's just their way of explaining why the Dartmouth Big Green can never seem to beat the Cornell Big Red.

Psychological Science via Discovery News.