“We are but ripples in a long, long stream… Nobody goes off trail and nobody walks alone. We have each other. We’re safe. That is how we survive,” Marigold Brandyfoot tells her daughter in Rings of Power. It appears that the formula didn’t just work for the Harfoots; according to a new study, human sperms, too, might fare better in groups than by themselves.
Published in Frontiers in Cell and Developmental Biology, the study found that by cooperating with each other, sperms can increase their likelihood of mating. The finding adds to research about sperm behavior that could enhance fertility technologies in the future.
When swimming in clusters, it’s not like sperms acquire greater speed than they would if they were navigating their way to a female egg cell on their lonesome. “They are not faster… in terms of speed, they are comparable or slower,” explained co-author Chih-Kuan Tung from the department of physics at the North Carolina A&T State University.
Instead, the advantage of being in a group is a better sense of direction, demonstrated by their straight-ish tracks — otherwise, they tend to take curved paths. This enables cooperative sperms, then, to stay on course. As the researchers noticed, too, clusters of sperm performed better while heading upstream into the mucus flow, as opposed to loner sperm that lost track and headed off in other directions.
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So, even if a loner sperm was speedier, the fact that it might deviate off course more easily, reduce its chances of mating. This upends the popular paradigm about sperm and fertility: that the fastest swimmers win.
Past research, too, has questioned this paradigm. A 2012 study had found that suggesting that longer and slower sperm have a greater likelihood of fertilizing an egg. Why that happens, researchers aren’t quite sure yet.
It’s a matter, then, of slow and steady winning the race. “Like the sperm equivalent of herds of tortoises racing individual hares, the winners are not necessarily the swiftest but rather the ones that can stay on target,” noted science writer James Riordon in Science News.
The researchers used bovine sperm for their experiments since their dimensions and dynamics both resemble those of humans — they, too, compete to fertilize a single ovum, and make their way from the vagina through the cervix to reach the uterus, unlike other animals whose sperms are deposited directly into their female counterparts’ uterus.
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Tung believes that the finding might help scientists gain deeper insights into infertility in humans.
Research suggests that although about 50% of infertility cases result from male factors, studies on fertility are focused heavily on the female reproductive anatomy. The present findings rooted in sperm research, however, challenge our gendered perception of fertility itself.
Not only that, it could be a “very big deal” for further research into fertility assistance as well, according to Christopher Barratt, a fertility researcher from the University of Dundee in Scotland who wasn’t involved in the study. Tung, too, is hopeful that an improved understanding of sperm dynamics could pave the path for better approaches to IVF — or in vitro fertilization — procedures.
As Barratt says, “How a sperm cell responds to its surroundings and how that may change its behavior is a very important subject… This type of technology could be used, or adapted, to select better quality sperm.”
