It wasn’t long before he decided to look at his ejaculate — definitely not by accident — and found tiny, wagging creatures with tails, which he called “animals.”
As scientists continue to look down on their microscopes over the centuries, there is no doubt what they see and record their eyes on film: Sperm swim by moving their tails to the side.
Why shouldn’t we trust our eyes? So science has believed in that ever since.
It turns out that our eyes were wrong.
“If you want to see the real beating of the tail, you have to move with the sperm and rotate with the sperm. So it’s almost like you have to make a (camera) really tiny and stick it to the head of the sperm,” Gadelha said.
Gadelha’s co-authors, Gabriel Corkidi and Alberto Darson of the Universidad Nacional Autonoma de Mexico in Mexico, have developed a way to do this. Using state-of-the-art instruments, including a super-high-speed camera that can record more than 55,000 frames per second, the researchers were able to see that sideways movement is actually an optical illusion.
In fact, the tail of the sperm lashes only on one side.
This unilateral blow should make sperm swim in a perpetual circle, Gadelha said. But no, the sperm were smarter than that.
“Human sperm have invented if they roll while swimming. Like playful otters that are pressed with water, their one-sided blow will turn to medium and they will swim forward,” said Gadelha, an expert in fertility mathematics.
“The rotation of the sperm is something that is very important. It is something that allows the sperm to regain symmetry and actually be able to go straight,” he said.
The findings came as a real surprise, Gadelha said, so the team spent nearly two years repeating the experiment and cross-checking the math. Retained results: just like the Earth turned out not to be flat, the sperm don’t actually swim like snakes or eels.
So why does this matter?
“It may be that the gait hides some subtle aspects to the health of this sperm or how well it can travel fast,” Gadelha said.
“These are very hypothetical questions. We hope that more scientists and fertility experts will be interested and ask, ‘OK, how does this affect infertility?’ “
As for what it feels like to turn over 300 years of scientific speculation, Gadelha is modest.
“Oh my God, I always have a deep feeling that I’m always wrong,” he said.
“Who knows what we’ll find next? It’s a measurement given by an instrument that has its limitations. We’re right right now, but we could be wrong again as science advances. And we hope it’s going to be something very exciting that we will learn in the next few years. “