- Male gorillas have the smallest penis of all apes, measuring 1.1 inches on average
- Scientists have identified the genetic mutation responsible for this adaptation
Standing up to 6 feet tall and weighing a staggering 500 pounds, it’s safe to say that gorillas are some of the most formidable creatures in the animal kingdom.
But despite their impressive stature, male gorillas are missing from one area in particular.
Great apes have the smallest penis of all apes, 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 pounds, it’s safe to say that gorillas are some of the most formidable creatures in the animal kingdom. But despite their impressive stature, male gorillas are missing in one particular area (file image)
Male gorillas have very small penises and testicles and produce little sperm.
Previous studies have attributed this to their polygynous mating system.
Within a pack, the alpha male is physically larger than the other males, giving him almost exclusive access to females.
This means that his sperm does not compete with the sperm of other males within the female reproductive tract.
“There are two ways to compete for mates: you can use your body or your sperm,” said Dr. Vincent Lynch, who led the study.
‘Most mammals use a combination of both. Gorillas use only their bodies.
Male gorillas have very small penises and testicles and produce little sperm. Previous studies have attributed this to their polygynous mating system (file image)
The researchers suggest that a lack of sperm competition likely led to the evolution of gorillas’ small testicles, as well as their low sperm count.
And in their new study, they set out to understand whether the genetic mutations behind them could also explain why some men have difficulty conceiving.
“We have a set of genes that are involved in sperm biology and have the signatures of harmful mutations in gorillas,” Dr. Lynch said.
«Then we can look at those same genes in infertile men and see if they have mutations.
“In this case, the gorilla genome essentially acts as a discovery tool to find candidate genes for human male fertility that we would not have been able to identify before.”
The researchers analyzed more than 13,000 genes in 261 mammals and found that 578 (4.3 percent) showed the same signatures as the gorilla lineage.
To test the impacts of these genes on male fertility, the team used gene editing to delete them in a fruit fly, Drosophila melanogaster.
They found that deleting these genes affected the reproductive function of males.
The team next analyzed the gorilla’s genes with those of 2,100 infertile men, revealing 109 genes linked to loss of function in men.
“Just a few years ago, there were not enough sequenced genomes or computing power to do these types of studies,” Dr. Lynch added.
“As science collects more genetic data, we will better understand why infertility occurs.”
