Have you ever noticed that Santa’s rosy cheeks are visible despite his furry face? It is as if his facial hair “purposely” keeps out of the way of his color signals. I have argued in my research that some of us primates evolved bare faces (and rumps) in order to color signal. In fact, our color vision appears to be optimized for sensing these blood-modulated color signals. I talk about this in detail in Chapter 1 of The Vision Revolution, and you can also find a variety of pieces related to this on my ChangiziBlog.
Research by Dr Mark Changizi of America’s Rensselaer Polytechnic Institute has suggested that we may have evolved our particular brand of colour vision to discriminate between slight changes in skin tone due to blushing, rage and blanching.
A survey of our primate relatives suggests that this kind of vision is only found in those with bare faces, such as humans, and is tuned precisely to detect changes in skin tone.
But even a beard as luxuriant as Santa’s should not hinder his ability to send out a colour signal, such as a healthy glow. After all, says Dr Changizi, we could have evolved to sprout hair anywhere – for example, on the cheeks, forehead and nose, which are the first areas to go red.
“But facial hair doesn’t end up there,” he points out. “You can really appreciate what beards don’t do by looking at men with the condition of hypertrichosis, when their faces are covered with hair.
“In terms of Father Christmas, note how the songs mention his rosy cheeks. Even Santa can colour-signal, despite his facial hair, because evolution has made sure that his beard and moustache got out of the way.”