On the Other Hand

Handedness, a conspicuous but enigmatic human trait, may be shared by other animals. What does it mean for evolution and brain function?

Written byBob Grant

| 12 min read

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With almost complete certainty, I can predict that you, dear reader, are right-handed. If I were a betting man, I’d put money on it. I’d make the same bet if you were reading this in India or Iowa, Kansas or Kathmandu. And a hundred years from now, I’d make the same bet again.

I can be so sure of myself not because I am some prodigious prognosticator, but because about 90 percent of humans are right-handed. That phenotypic ratio—nine right-handed people for every lefty—is relatively stable, not just across cultures and geographic regions, but perhaps across the span of human evolution. The archaeological record suggests that hominins were predominantly right-handed as far back as 2 million years ago,1 and a 2010 study of the wear patterns on 32,000-year-old Neanderthal teeth found that this extinct cousin of Homo sapiens was likely about 88 percent right-handed.2 It’s a ratio that has baffled scientists for more ...

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Meet the Author

Bob Grant
From 2017 to 2022, Bob Grant was Editor in Chief of The Scientist, where he started in 2007 as a Staff Writer. Before joining the team, he worked as a reporter at Audubon and earned a master’s degree in science journalism from New York University. In his previous life, he pursued a career in science, getting a bachelor’s degree in wildlife biology from Montana State University and a master’s degree in marine biology from the College of Charleston in South Carolina. Bob edited Reading Frames and other sections of the magazine.
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