February '21

We consider red to be modern and sexy. About 30-50 million years ago, our monkey forefathers’ eyes were equipped with two types of photoreceptor cells. One type specialized in the blue part of the spectrum, the other detected green. Red was invisible.

When primates separated as a species, the eye was given “red” sensors. Some anthropologists believe that identifying ripe fruit among green leaves provided an evolutionary advantage to our predecessors. The inability to do so also possibly infuriated primates to the point of seeing red. That is less romantic, though.

Luckily there are other hypotheses. One of them links the ability to see red with estrogen, a female hormone that, among other things, improves blood flow in the face. Given that estrogen levels are highest right before the peak of fertility, one hypothesis says males able to detect well-perfused and thus slightly reddish females were better equipped to time their courting.

Sharp-eyed monkey-boys had more monkey-babies. Their genes with improved eyesight prevailed. Red did not become sexy because we liked the sight of it. On the contrary: we started seeing it because red is sexy. You be the judge of whether we fell down the rabbit hole of evolutionary sensationalism.