Nuts! That showy male is making up for small balls
The smaller a primate's testicles, the larger its secondary sexual characteristics, but how does it apply to humans?
Swiss and Australian scientists have spent months measuring primate testicles to answer the age-old question: is that monkey (or human) compensating for something?
Well, their findings have shown that, yes, it’s rare for primates to be both well-endowed (testicularly, of course) and also have the badges of status that attract females.
The researchers, from the universities of Western Australia and Zurich, published their findings in the scientific journal, the Proceedings of the Royal Society B, last week.
The study showed that, on average, primates who are great at attracting mates through showy behaviour – what could be described as bro-like alpha male shows of strength – or beautiful secondary characteristics, have smaller balls.
So next time you see an orangutan with a massive flange (flesh around the neck area), a gelada monkey with a luscious crest of red hair on its chest, or a proboscis monkey with a gigantic nose, feel comforted in the knowledge that their nuts are probably tiny.
And those shy, average looking apes? Well, their larger testes are churning out vast amounts of sperm, meaning they still have a good chance of continuing their genetic line.
Paleoanthropologist at the University of Johannesburg’s Paleosciences Research Institute, Stephanie Edward Baker, explained that the study doesn’t apply to humans to quite the same extent, as throughout our evolution we’ve tended to discard those secondary characteristics.
The huge canines that female apes swoon for, the crests and flanges, humans no longer require.
“We no longer have to be visible from across the savannah to attract a mate, so we often just have to rely on our behaviour,” she said.
However, that doesn’t mean that humans aren’t still using other methods to compensate for what they may perceive as inadequacies.
“We’ve swapped out those physical characteristics with something more symbolic – like the ability to afford a Ferrari,” said Baker.
She did say there were some vestigial physical characteristics to attract mates, like slightly larger canines for human men, but that it was almost impossible to make blanket statements for humans.
“There is so much variability between population groups. People who come from Sweden are hellishly tall, for example,” she said.
She was also quick to point out that humans generally have larger testicles than the average primate, and that most of the primates in the animal kingdom keep their testicles on the inside, unlike humans who proudly display them – under their clothes, of course.
“Humans no longer have to fight physically to attract mates, so the testicles evolved to be bigger. Think about it, large testicles (for primates) would be a wonderful target to, quite frankly, bite off. In a fight, they’d be incapacitated right then and there,” she said.
She said this study could be an entryway into further research into human behaviour of antiquity, and how our behaviour changes have occurred to attract mates. “We can all have a laugh about a study about testicles, but they are so incredibly important to sexual reproduction ... Ultimately, we’re all just trying to have as much sex as possible, that’s the crux of evolution!”
The Royal Society study was compiled across more than 100 animal species (including humans) but mainly focused on primates due to the huge variation in testicle size and the different types of ornamentation present. Some of the animals showed testicles as large as tennis balls, while others were smaller than a pea.