- Male gorillas have the smallest penises of any ape, measuring an average of 1.1 inches
- Scientists have identified the gene mutation responsible for this adaptation
Standing up to 6 feet tall and weighing a staggering 500 lbs, it’s safe to say that gorillas are some of the most fearsome creatures in the animal kingdom.
But despite their imposing stature, male gorillas are lacking in one particular area.
Great apes have the smallest penises of any ape, with the average member measuring just 1.1 inches long.
Now scientists at the University at Buffalo have identified the genetic mutation responsible for this adaptation.
And they say the discovery could help explain why some men are infertile.
Standing up to 6 feet tall and weighing a staggering 500 lbs, it’s safe to say that gorillas are some of the most fearsome creatures in the animal kingdom. But despite their impressive stature, male gorillas are lacking in one particular area (image)
Male gorillas have very small penises and testicles and produce little sperm.
Previous studies attributed this to their polygynous mating system.
In the group, the alpha male is physically larger than the other males, giving him almost exclusive access to the females.
This means that his sperm does not compete with the sperm of other males in the female reproductive tract.
“There are two ways to compete for mates: you can either use your body or your sperm,” said Dr Vincent Lynch, who led the study.
“Most mammals use a combination of the two. Gorillas only use their bodies.
Male gorillas have very small penises and testicles and produce little sperm. Previous studies attributed this to their polygynous mating system (image)
The researchers suggest that the lack of sperm competition likely led to the evolution of gorillas’ small testicles, as well as their low sperm counts.
And in their new study, they sought to find out whether the gene mutations behind them could also explain why some men struggle to conceive.
“We have a set of genes that are involved in sperm biology that have the hallmarks of deleterious mutations in gorillas,” Dr. Lynch said.
“We can then look at these same genes in infertile men and see if they have mutations.
“Here, the gorilla genome essentially acts as a discovery tool to find candidate genes for human male fertility that we could not previously identify.”
The researchers analyzed more than 13,000 genes in 261 mammals and found that 578 (4.3 percent) show the same signatures as the gorilla.
To test the impact of these genes on male fertility, the team used gene editing to delete them in the fruit fly Drosophila melanogaster.
They found that deleting these genes affected the male flies’ reproductive function.
The team then analyzed the gorilla’s genes with those of 2,100 infertile men, revealing 109 genes associated with the loss of function in men.
“Just a few years ago, there weren’t enough sequenced genomes and enough computing power to carry out these kinds of studies,” added Dr. Lynch.
“As science collects more genetic data, we will have a better understanding of why infertility occurs.”
