Human sperm get lost in space, pioneering study finds
Researchers put human sperm inside a uteruslike simulation under microgravity conditions. It did not go well
Sperm may be negatively affected by a lack of gravity, a new study shows.
Sperm and Embryo Biology Laboratory, Adelaide University
On Earth, human sperm typically navigate effectively to fertilize an egg. However, a recent study indicates that this may not be the case in space. The research suggests that human sperm may encounter difficulties in navigating under microgravity, which poses questions about the feasibility of human reproduction in space.
Scientists conducted an experiment by placing human sperm in a simulated microgravity environment that mimics the female reproductive system. The results showed that the sperm struggled with “impaired directional navigation” more frequently than they do under Earth’s typical gravity.
Furthermore, the study observed a notable impact on mouse eggs, with a 30 percent decrease in fertilization rates under microgravity conditions over a four-hour period compared to Earth’s gravity.
On supporting science journalism
If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
The findings, published in the journal Communications Biology, could provide insights for future human reproduction in space. NASA and other space agencies assert that no one has engaged in sexual activity in space, but future space travelers might wish to start families while living in a microgravity environment.
According to Nicole McPherson, the study’s senior author and a lecturer at Adelaide University in Australia, “As missions to the moon and Mars transition from dreams to reality, understanding if humans and the species we rely on can reproduce in these settings is not merely an interest; it’s a necessity.”
Interestingly, the addition of progesterone, a hormone emitted by egg cells, improved the sperm’s orientation in the simulated microgravity environment.
“Progesterone acts as a chemical signal, serving as a biological homing beacon released by the egg during ovulation,” McPherson explains. “Sperm have receptors that detect this signal, guiding them to swim toward its source.”
She adds, “This is one of nature’s more sophisticated navigation systems.”
However, McPherson notes that the progesterone was effective only at concentrations “considerably higher” than naturally occurring levels. While these findings are intriguing, she mentions, “We are not yet suggesting progesterone as a straightforward solution for fertility in space.”
“Nevertheless,” she concludes, “it opens up a fascinating avenue for future research.”
It’s Time to Stand Up for Science
If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.
I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.
If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.
In return, you get essential news, captivating podcasts, brilliant infographics, can’t-miss newsletters, must-watch videos, challenging games, and the science world’s best writing and reporting. You can even gift someone a subscription.
There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.
