SSS 2011-04-21

（单词翻译）

This is Scientific American’s 60-Second Science. I’m Karen Hopkin. This will just take a minute.

When it comes to handedness, righties rule. And according to a new study, they have for a long time, because even half a million years ago, nine out of 10 European humans favored their right hands. The finding appears in the journal Laterality.

Scientists have long wondered where our handedness comes from. All other tool-using primates¹ show no distinct hand preference when it comes to holding the stick or stone.

But have humans always been so heavily right-handed? Some scientists had previously² detected a right-hand bias³ when they looked at the flaking⁴ patterns on ancient stone tools.

In this study, researchers turned to the teeth for answers. They analyzed⁵ the scratches accidentally left by stone tools on teeth from human fossils collected from a half-million-year-old site in northern Spain and later sites throughout Europe. These asymmetrical⁶ marks showed that 93 percent of the individuals sampled tended to stuff things in their mouths from the right-hand side.

Handedness reflects our brain’s bilateral⁷ organization, which goes hand-in-hand with our proficiency⁸ with language. So our hand preference, and our penchant⁹ for speech, may extend deep into our evolutionary¹⁰ past.

Thanks for the minute. For Scientific American’s 60-Second Science, I’m Karen Hopkin.