Blue Testicles – Did You Know…

… 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???


get the InLinkz code


30 thoughts on “Blue Testicles – Did You Know…

  1. Actually I recently developed a dark blue/violet one though I’m sure it’s nor the Tyndall effect. It”s more to do with my granddaughter launching a bottle of water into space where it could only produce a low orbit. This particular hue also comes with odd groans and the expulsion of coffee into the surrounding atmosphere giving my trousers the impression that their content is incontinent.
    xxx Huge Hugs xxx

    Liked by 1 person

  2. I didn’t know, but, as I often say, you can’t just make this stuff up. This is also a perfect example that nothing is stranger than the truth. I just hope that this fact does not become too well publicized as I fear that science may research and devise this condition in the animal kingdom and then figure out some way to get the same effect in humans. Then, in addition to Viagra and Cialis commercials, I would have to sit through something similar for this new drug. Why is it that males seem to always want to be bigger, better and more colorful, when females, at least of the human variety, generally could hardly care less about these physical appearance attributes?

    Liked by 1 person

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