Study: Scouting the Olympics of Sperm

Longer sperm fare better in the race to fertilization, but speed is actually not a factor.

2959254617_b8e1f396a7_zmain.jpgFlickr

PROBLEM: The fastest Olympic swimmer always gets the gold. If we replace "Olympic swimmer" with "sperm" and "gets the gold" with "fertilizes the egg," does the same hold true?

METHODOLOGY: It's fun to picture how this must have gone down: First, scientists organized male fruit flies into two groups based on similar, and naturally occurring, sperm traits. Then, they mated one fly from each group with the same female. The flies had been genetically modified to produce fluorescent sperm -- one group glowed green, the other, red. This allowed scientists to observe and compare the two groups of sperm "in real time" while they were traveling down the female reproductive tract, to see how competition affected their behavior.

RESULTS: Scientists observed battles between rival sperm in the reproductive tract. Regardless of who got there first, the sperm would wait in a "storage area" until the female released eggs. Each time the female mated, the new sperm would arrive in this area and attempt to force the old sperm out. Longer and slower sperm were better at kicking out the other guys, and they were less likely to be ejected themselves.

CONCLUSION: A sperm's length is positively associated with its likelihood of successful fertilization (which we already knew) -- speed, however, is not an advantage.

The full study, " How Multivariate Ejaculate Traits Determine Competitive Fertilization Success in Drosophila melanogaster," will be published in the journal Current Biology.

Presented by

Lindsay Abrams is an assistant editor at Salon and a former writer and producer for The Atlantic's Health Channel.

The Case for Napping at Work

Most Americans don't get enough sleep. More and more employers are trying to help address that.

Join the Discussion

After you comment, click Post. If you’re not already logged in you will be asked to log in or register.

blog comments powered by Disqus

Video

The Case for Napping at Work

Most Americans don't get enough sleep. More and more employers are trying to help address that.

Video

A Four-Dimensional Tour of Boston

In this groundbreaking video, time moves at multiple speeds within a single frame.

Video

Who Made Pop Music So Repetitive? You Did.

If pop music is too homogenous, that's because listeners want it that way.

Video

Playing An Actual Keyboard Cat

A music video transforms food, pets, and objects into extraordinary instruments.

Video

Stunning GoPro Footage of a Wildfire

In the field with America’s elite Native American firefighting crew

Video

The Man Who Built a Forest Larger Than Central Park

Since 1979, he has planted more than 1,300 acres of trees.

More in Health

Just In