Brain Temperature and Animal Coloration
The hue-heat effect, interpreted as a universal preference for darker colors in hotter environments and brighter colors in colder environments, is the simplest explanation for the ecogeographical effect known as Gloger’s rule.
“Consequently, the closer the skin is to the Equator, the darker and more melanized it is. The closer the skin is to the pole, the lighter and less melanized it is” (Cibangu 2015).
Studies have shown repeatedly that human subjects adjust their determination of the temperature of an object based on its color, or the temperature of a room depending on whether it’s filled with redder or bluer light (Mogensen and English 1926, Berry 1961, Ziat et al. 2016, Albers 2015). Darker colors are judged to be cooler than brighter colors. White, red, orange and yellow look hot and black and blue look colder.
This is known as the hue-heat effect, and it provides a simple, obvious explanation for Gloger’s rule that animals are darker in warmer environments and brighter in colder environments. The effect can be stated, as usual, in terms of thermal comfort:
“The Hue Heat Hypothesis (HHH) is based on the idea that light and colours of the environment can affect thermal perception and influence thermal comfort. Specifically, it states that, when spectral power distribution of light reaching an observer’s eye is characterized by long [redder] wavelengths in the visible spectrum, the space is perceived as warmer; conversely, when small [bluer] wavelengths are predominant, the space is perceived as cooler” (Bellia et al. 2019).
It can also be put in terms of preferences. People at higher temperatures, with hotter bodies and brains, prefer darker…