Over the years, scientists have come up with a lot of ideas about why we sleep.

Some have argued that it’s a way to save energy. Others have suggested that slumber provides an opportunity to clear away the brain’s cellular waste. Still others have proposed that sleep simply forces animals to lie still, letting them hide from predators.

A pair of papers published on Thursday in the journal Science offer evidence for another notion: We sleep to forget some of the things we learn each day.

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Our fellow primates are in trouble.

In a study of unprecedented scope, a team of 31 primatologists has analyzed every known species of primate to judge how they are faring. The news for man’s closest animal relatives is not good.

Three-quarters of primate species are in decline, the researchers found, and about 60 percent are now threatened with extinction. From gorillas to gibbons, primates are in significantly worse shape now than in recent decades because of the devastation from agriculture, hunting and mining.

Continue reading “Most Primate Species Threatened With Extinction, Scientists Find” →