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.

How to Cook Spaghetti Squash (and Why)

Cooking for yourself is one of the surest ways to eat well. Bestselling author Mark Bittman teaches James Hamblin the recipe that everyone is Googling.

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

How to Cook Spaghetti Squash (and Why)

Cooking for yourself is one of the surest ways to eat well.

Video

Before Tinder, a Tree

Looking for your soulmate? Write a letter to the "Bridegroom's Oak" in Germany.

Video

The Health Benefits of Going Outside

People spend too much time indoors. One solution: ecotherapy.

Video

Where High Tech Meets the 1950s

Why did Green Bank, West Virginia, ban wireless signals? For science.

Video

Yes, Quidditch Is Real

How J.K. Rowling's magical sport spread from Hogwarts to college campuses

Video

Would You Live in a Treehouse?

A treehouse can be an ideal office space, vacation rental, and way of reconnecting with your youth.

More in Health

Just In