The Swimming Speed of Sperm

New research done at Max Planck Gesellschaft has found that it isn't the concentration of chemicals released by the egg that control the speed of sperm, but a derivative of that.

Sperm fertilizing an egg Sashkin/Shutterstock

Our male readers will be happy to learn that their sperm is even smarter than they thought.  It's been known that the egg releases chemicals that alter the concentration of calcium inside the sperm, which in turn changes how fast the sperm wag their tails.

Turns out that it's not the concentration level itself that controls the speed, but the change in the concentration. That means that sperm are calculating the first time derivative of the levels of calcium, something we thought can only be done about 16 years after conception.

More about the research done at Max Planck Gesellschaft:

Using an ingenious stroboscopic laser illumination -- similar to that used in discotheques -- the project leader Luis Alvarez was able to trace the movement of sperm in detail, and simultaneously measure the changes in the calcium concentration. The result was astonishing: the sperm tail only reacted to the time derivative of the calcium concentration and the absolute concentration was of little relevance. To put it simply: Sperm can perform calculus! Exactly how they do this is unclear. The caesar scientists suspect that sperm detect calcium ions with the help of two proteins. Calcium binds to one protein fast and to the other slow. By comparing the amount of calcium bound on both proteins can compute a "chemical derivative," so to speak.

But why do sperm carry out this complicated calculation that we first encounter at the upper secondary school level? The concentration of the attractants and, therefore also the calcium concentration in sperm is very high near the egg. The mathematical trick probably enables sperm to be able to react even in the presence of such high calcium concentrations.


This post also appears on medGadget, an Atlantic partner site.

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