Article image

Same genes that cause human infertility made gorilla penises small

Male gorillas may seem like the epitome of fertility, but their biology tells a different story. Despite their imposing size, male gorillas possess relatively small testes and produce sperm with lower motility, characteristics typically associated with infertility in humans.

Surprisingly, these seemingly contradictory traits in gorillas might hold the key to unlocking the mysteries of male infertility in humans. By studying the reproductive biology of gorillas, scientists hope to gain a deeper understanding of the factors that influence sperm production and function.

University at Buffalo researchers have made a significant breakthrough in the field of male infertility. Their study focused on identifying genes responsible for the unique reproductive traits of gorillas, which include small testes and low sperm motility. They discovered 109 genes that, when mutated, negatively impact the gorilla’s reproductive system.

The most intriguing aspect of this discovery is that these same genes are frequently found mutated in infertile men. This suggests a shared genetic basis for male infertility in both humans and gorillas, potentially opening up new avenues for research and treatment.

“We have a set of genes that are involved in sperm biology and have the signatures of harmful mutations when in gorillas. We can then look at those same genes in infertile men and see if they have mutations,” says Dr. Vincent Lynch, lead author of the study. This unexpected connection suggests that gorillas could be the unlikely heroes in our fight against human male infertility.

Why gorillas don’t need impressive sperm

Male gorillas’ reproductive shortcomings are a result of their polygynous mating system. In simpler terms, the dominant silverback’s sheer size and strength give him almost exclusive access to the females in his group. There’s no need for a sperm race when you’re the only contender.

“There are two ways to compete for mates: You can either use your body or your sperm,” Lynch explains. “Most mammals use a combination of both. Gorillas use only their bodies.” This lack of sperm competition has led to an evolutionary trade-off. Gorillas have sacrificed sperm quality for physical dominance.

Gorillas and human infertility

Human infertility affects a significant number of couples, and the genetic causes are often unclear. The gorilla’s genome is shedding light on this complex infertility issue.

“So rather than looking at all of a man’s genes for rare mutations, you could look at only those genes whose gorilla counterparts cause abnormal sperm biology,” says Jacob Bowman, a postdoctoral researcher and the study’s first author.

By studying gorillas‘ “relaxed” genes – those with mutations that would typically be eliminated but have persisted due to lack of sperm competition – researchers can pinpoint genes that play a crucial role in human fertility.

Fruit flies and altered genes

Scientists have already made progress using fruit flies to study the effects of deleting gorilla genes. By removing these specific genes in the insects, researchers could observe the resulting changes. The experiments confirmed that many of these genes are essential for male reproductive function.

This means that the same genes affecting gorilla reproduction play crucial roles in the reproductive systems of other species, including humans. This cross-species genetic approach offers valuable insights into the underlying causes of male infertility.

“Most of the genes that are important for reproductive biology are conserved across many different species, including Drosophila, and you can do these loss-of-function experiments at scale in Drosophila in a way that you can’t in other organisms,” says Lynch.

Future of male infertility treatment

This research is still in its early stages, but it opens a new avenue for understanding and addressing male infertility. By pinpointing the genetic mutations associated with infertility, scientists may develop targeted treatments and therapies.

“Just a few years ago, there weren’t enough sequenced genomes and computing power to conduct these kind of studies. As science collects more genetic data, we’ll have a better understanding of why infertility happens,” said Lynch.

The mighty gorilla, with its less-than-mighty reproductive system, may hold the key to unlocking the secrets of human male infertility. This research is a testament to the interconnectedness of species and the power of scientific inquiry. While there’s still much to learn, the future of fertility research looks promising – thanks in part to our unlikely ally, the gorilla.

The study is published in the journal eLife.


Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and


News coming your way
The biggest news about our planet delivered to you each day