… That several African primates (like vervets and mandrills) sport vibrant color for a very specific reason?
“Adding a pop of colour to a neutral outfit can really brighten it up. It also helps to know where to put it.
Male old World monkeys—including patas, mandrills, vervets, talapoins, and lesula—sport their, um, accessories in an unusual place.” – National Geographic
Just so you know, blue testicles are not due to sexual frustration (or a very violent partner…). The blue color is also not caused by hormonal shifts (as with red color Baboons and what some other primates “wear”).
While in some cases those blue pigments (which are not entirely understood) are linked to sexual selection, in case of mandarins this blue coloring stands for social status.
“Male mandrills, native to rain forests of equtorial Africa, have vivid red and blue facial colors that match the eye-catching colors on their hindquarters. With a brighter the face, rump, and genitalia, comes a higher male’s rank, which a 2005 study showed could sometimes help avoid costly conflict. What’s more, female mandrills prefer males with more vibrant colors.
Male vervets of East Africa that have more intense blue scrota are “more likely to be aggressive with and bully juvenile males,” says Jennifer Danzy Cramer, a biological anthropologist at American Public University in Charles Town, West Virginia.
Vervets also like to show off their bonnie blues, unlike mandrills and patas, a primate native to central African grasslands.
Overall, greater contrast and larger size “are probably alluring traits” (think eye-catching peacock’s tail) so those males with most vibrant and biggest scrota attract females. For instance, patas testicles can grow to twice their size during mating season.
– National Geographic
So how do primates actually get their blue… balls?
On a molecular level it’s due to so called Tyndall effect (scattering of light by our skin itself). According to a study skin of blue-hued monkeys has unusually neat collagen fibres. They are so well organized that their tiniest change would produce a different color.
And that means: Monkeys can take on different hues.
lesula, an African primate, only formally discovered in 2007, has a bright blue scrotum and buttocks that turns white when this animal dies.
Patas have aquamarine scrota, while many adult vervets’ are more turquoise.
Apparently all male vervet monkeys start off with dull, dark, dusty blue scrota with differences only emerging during adulthood.
For instance, a green monkey, a vervet native to West Africa and the West Indies, has genitalia that turns a pale blue or even white in adulthood.
Quite some colorful family jewels, don’t you think…
This post is also today’s contribution for the Taboo Word Challenge. The word I was avoiding was “the”.
I can’t believe it’s the last one. Where did time go???