theweekmagazine:

About 10 percent of people favor their left hand, a ratio that has remained constant for more than 5,000 years. Scientists may have finally figured out why.

It’s all about the balance between cooperation and competition. Humans have long had an evolutionary need to cooperate, such as when sharing tools or hunting in groups. And if most people use the same hand, it makes such cooperation easier. “The more social the animal — where cooperation is highly valued — the more the general population will trend toward one side,” says co-author Daniel M. Abrams.

So why do we have lefties at all? Because people aren’t purely cooperative. We compete with each other, too, and always have. “If a society was totally cooperative, then everyone would be same-handed,” says Nauert. But that’s not us. Our competitive streak ensures that there will always be lefties.

Phys.Org:

[The researchers] turned to the world of sports for data to support their balance of cooperation and competition theory. Their model accurately predicted the number of elite left-handed athletes in baseball, boxing, hockey, fencing and table tennis — more than 50 percent among top baseball players and well above 10 percent (the general population rate) for the other sports.

On the other hand, the number of successful left-handed PGA golfers is very low, only 4 percent. The model also accurately predicted this.

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