In general, about one-tenth of the world’s population are southpaws.

Have you ever wondered what is means to be left-handed and why this trait happens at all? Daniel M. Abrams investigates how the uneven ratio of lefties and righties gives insight into a balance between competitive and cooperative pressures on human evolution.

“Archaeological evidence shows that it’s been that way for as long as 500,000 years with about 10% of human remains showing the associated differences in arm length and bone density, and some ancient tools and artifacts showing evidence of left-hand use.”

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Lesson by Daniel M. Abrams, animation by TED-Ed.

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