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.

Things Not to Say to a Pregnant Woman

You don't have to tell her how big she is. You don't need to touch her belly.

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

Things Not to Say to a Pregnant Woman

You don't have to tell her how big she is. You don't need to touch her belly.

Video

Maine's Underground Street Art

"Graffiti is the farthest thing from anarchy."

Video

The Joy of Running in a Beautiful Place

A love letter to California's Marin Headlands

Video

'I Didn't Even Know What I Was Going Through'

A 17-year-old describes his struggles with depression.

Video

Google Street View, Transformed Into a Tiny Planet

A 360-degree tour of our world, made entirely from Google's panoramas

Video

The Farmer Who Won't Quit

A filmmaker returns to his hometown to profile the patriarch of a family farm

Video

Riding Unicycles in a Cave

"If you fall down and break your leg, there's no way out."

Video

Carrot: A Pitch-Perfect Satire of Tech

"It's not just a vegetable. It's what a vegetable should be."

More in Health

Just In