Previous: Is Sugar Alcohol as Awesome as It Sounds?
Next: 5 Undervalued Scientists: Great Minds Compilation



View count:181,528
Last sync:2018-05-12 04:30
Only 10% of the world is left handed, so why are so many athletes lefties?

Hosted by: Hank Green
Support SciShow by becoming a patron on Patreon:
Dooblydoo thanks go to the following Patreon supporters—we couldn't make SciShow without them! Shoutout to Kevin Bealer, Mark Terrio-Cameron, KatieMarie Magnone, Patrick Merrithew, Charles Southerland, Fatima Iqbal, Sultan Alkhulaifi, Tim Curwick, Scott Satovsky Jr, Philippe von Bergen, Bella Nash, Chris Peters, Patrick D. Ashmore, Piya Shedden, Charles George
Looking for SciShow elsewhere on the internet?
Most humans are "righties," people like me who use their right hands to write or... do football.

But even though only 10% of people are left-handed, 50% of professional fencers are "lefties." In fact, there are lots of "South-paws" competing in top-levels of sports, like boxing, tennis, and baseball, too.

So, what gives? Do left-handed people have some sort of, like, "good-at-sports" gene that the rest of us don't?

Turns out, how certain competitive athletes rise through the ranks can mirror how populations of animals change as they duke it out for survival. Let's say, you're a hungry House Sparrow that has two main food finding behaviors: there are producers, who spend a lot of time and energy hunting for meal-worms, or scroungers, who steal food from producers.

If there are lots of producers competing with each other to find food and not that many scroungers, the scrounging sparrows have it easier. There are lots of sparrows to steal from and it doesn't take a lot of energy to stay alive. But, if there are too many sparrows trying to steal and few finding meal-worms in the first place, the scroungers will starve, while the producers will be well fed.

Basically, the frequency of a behavior determines how successful it is, and the more common the behavior is, the worse it is for survival. So, ecologists call this a Negative Frequency Dependent Model.

This particular example shows how behaviors can change within a population of sparrows. Scientists also use this model to talk about how populations evolve over time because of selection: how animals with certain traits are more likely to survive and pass those traits on to their babies. Professional athletes can sometimes be modeled like animal populations because there are analogs for different generations and death. Some people win a lot and go on play at higher levels, while others remain at lower levels or stop playing.

In 1-on-1 sports, like boxing or tennis, there's direct competition between players, and success can depend on different traits, like how fast someone's reflexes are, or which hand they use. So a sort of selection can come into play.

Now, there doesn't seem to be an inherent advantage to be left-handed. They aren't faster or stronger athletes. But, they might do better as beginners in 1-on-1 competition sports because they're less common. If you're just starting out as a right-handed fencer, for instance, you have fewer chances to practice against "lefties," so their movements might be a little less familiar and you might lose more often.

Because there are so many right-handed people, left-handed athletes might be more successful early on, and rise through the ranks, which fits with a Negative Frequency Dependent Selection Model. At higher levels, though, the "lefty" advantage becomes weaker because the pools of athletes are more mixed.

There are a lot of other factors at play, too. So, this model probably isn't the only explanation for this pattern. But, wield those left-handed scissors, or foils, with pride! It can be helpful.

Thank you for asking, and thanks especially to our Patrons on Patreon, who keep these answers coming. If you would like to submit questions to be answered, you can go to And, don't forget to go to, and subscribe for more science in your subscription box every single day.