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03/15/2009 05:12 am ET Updated May 25, 2011

Humans First Got Crabs From Gorillas

Just as humans and gorillas share a common evolutionary ancestry, the pubic lice that infuriate some members of the two species are also related. Pubic lice--known to scientists as Pthirus pubis and to most other people as "crabs"--are thought to have evolved from Pthirus gorillae, the structurally similar species that infests gorillas. Genetic analysis by David Reed at the University of Florida indicates that the lice lineages split about 3.3 million years ago, whereas it is believed that humans diverged from gorillas at least 7 million years ago. This suggests that "early humans somehow caught pubic lice from their gorilla cousins."

Read on to find out how...

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