Seeing Red: Our Ancient Relationship With Ocher And The Color Of Cognition - Analysis
May 3, 2024
By Irina Matuzava
Extensive ocher use reflects the culture and cognitive abilities of early humans, who inherited an affinity for red from primate ancestors.
Twenty-three million years ago, our distant ancestors gained trichromatic color vision through means of a random genetic mutation. Trichromatic color vision and trichromacy refer to the ability to perceive color through three receptors in the eye, known as cones, which are sensitive to different wavelengths of visible light.
It has been assumed that primates ancestral to humans had two cones at the start of their lineage; the duplication and modification of genes coding for one of the two created another distinct, separate cone. Gaining a third cone allowed for the perception of red and other colors with long wavelengths in addition to the two preexisting receptors for blues and greens with shorter wavelengths—red was entirely unknown to primate species before this mutation, and the ability to see red remains rare among other mammals. Exceptions to mammalian dichromacy, the state of having two cones, are uncommon. Some primates lost one of their cone receptors, becoming monochromats. Having a single cone, monochromats like the nocturnal owl monkeys (genus Aotus) perceive light intensity in shades of gray without the ability to differentiate color values. Others, including the ancestors of modern apes, monkeys, and humans, happened to gain a third cone.
Michael H. Rowe, professor emeritus of neuroscience at Ohio University, confirms that random processes were involved in the evolution of primate trichromacy in his study of the underlying neurophysiological mechanisms, and outlines the two dominant theories for the maintenance of a third cone among primates. One longstanding theory is that of enhanced fruit detection among diurnal primates, who are most active during the daytime. According to this theory, improved discernment of red fruits against green foliage led to a direct increase in efficiency when foraging for nutritious food.
The second theory, however, suggests it was the consumption of leaves rather than fruit that more strongly influenced routine trichromacy. This alternate “young leaf” hypothesis emphasizes the importance of enhanced color vision when selecting nutritious leaves over their less beneficial counterparts, especially at times when fruit is scarce and surviving off of leaf consumption becomes critical. Rowe’s findings and the newer “young leaf” theory also align with the later evolution of trichromatic vision in the howler monkey, a New World primate.
More:
https://www.eurasiareview.com/03052024-seeing-red-our-ancient-relationship-with-ocher-and-the-color-of-cognition-analysis/
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