Wikipedia:Reference desk/Archives/Science/2021 June 3

= June 3 =

Colors of Hair across Mammals (vs. Colors of Feathers)
It appears that the hair of humans covers pretty much the same colors as colors across Mammalia: Black, Shades of Brown tending to Blonde and Red. However, I've never seen bright orange Hair in either humans or other animals, similarly for green and blue. 1) Are there colors that other Mammals have for hair which aren't found among humans? 2) Is there a particular reason that Birds seem to have feathers across most possible colors while Mammals do not have the same for Hair? Naraht (talk) 02:57, 3 June 2021 (UTC)
 * On your last question, it seems likely due to the fact that, unlike birds, mammals on the whole do not possess well-developed colour vision, due to their nocturnal origins. This Nature article states "birds have genera that possess rods and four spectral classes of cone each representing one of the five visual pigment families. The complement of four spectrally distinct cone classes endows these species with the potential for tetrachromatic colour vision. In contrast, probably because of their nocturnal ancestry, mammals have rod­-dominated retinas with colour vision reduced to a basic dichromatic system subserved by only two spectral classes of cone". Our article on Evolution of color vision states something similar. If mammals cannot see colour well, there is less evolutionary selection pressure for them to develop coloured hair. PaleCloudedWhite (talk) 03:45, 3 June 2021 (UTC)
 * Thank you.Naraht (talk) 11:20, 4 June 2021 (UTC)
 * Just so, but in my opinion bright orange is present by mammals, is this not the normal background color of a tiger? And some red haired humans have also a very similar color.2003:F5:6F0B:CD00:CC4B:78F5:1101:CC61 (talk) 00:15, 5 June 2021 (UTC) Marco PB


 * The blue and green colours of bird feathers are not due to pigments (carotenoids, melanins or porphyrins), but are instances of structural coloration, caused by refraction or scattering of reflected light due to the physical structure of these feathers. Structural coloration cannot be accomplished with the much simpler structure of hair. See further . --Lambiam 08:38, 3 June 2021 (UTC)
 * Ah. So the actual pigments in a bird's feather aren't blue. Interesting. Naraht (talk) 11:20, 4 June 2021 (UTC)


 * Does make you wonder what Animal Kingdom some of today's youth are. :)Naraht (talk) 11:20, 4 June 2021 (UTC)

Silverback gorillas
Is there a significant difference between the transformation at the follicle level of a male Gorilla's hair changing to make them a Silverback and a Human's head hair going gray?Naraht (talk) 02:59, 3 June 2021 (UTC)
 * I've been wondering about this for a while now. Abductive  (reasoning) 19:37, 3 June 2021 (UTC)
 * The graying process is known as achromotrichia (we don't have an article... weird), which is greek for "loss of hair color" a-= not -chromo- = color -trich- = hair. There is some information on the process at Human hair color.  This article discusses the process of graying in non-Human mammals; and while it doesn't specifically address the biochemistry of the process, it also does not indicate that it is any different than in humans.  For silverback gorillas, it appears to be some genetically linked hormone-induced process associated with the gorilla equivalent of puberty, as it essentially happens in all male gorillas upon reaching a certain age, according to that article.  -- Jayron 32 13:42, 4 June 2021 (UTC)
 * The term achromotrichia means neither more nor less than the absence of pigment in hair, whether congenital, or lost as a natural aspect of aging, or as the result of a disease. Cattle grazing pastures high in molybdenium may develop a syndrome one of whose characteristics is achromotrichia. --Lambiam 09:16, 5 June 2021 (UTC)
 * So becoming a Silverback is something that happens at the equivalent of the Human age of 16, not at the equivalent age to the Human age of 50.Naraht (talk) 18:58, 9 June 2021 (UTC)
 * Well, sort of. From a biochemical point of view, the greying of hair is the same whether it is due to senescence or due to puberty.  The difference is when it happens in Gorillas.  -- Jayron 32 16:02, 10 June 2021 (UTC)