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1·Contagious: a human head louse clings to a strand of hair.

感染力：附着在一根头发上的人类头虱。

2·The head louse, Pediculus humanus capitis is a tiny insect which lives on the hair. Occasionally, it is also seen in the eyebrows or beard.

头虱是一种寄生于头发上的细小昆虫，有时亦会在眼眉或胡须间出现。

3·The human head louse, for instance, evolved from the chimpanzee louse when the ancestors of humans and chimps split apart some five million years ago.

例如，人头虱是500万年前当人类祖先与黑猩猩分化时从黑猩猩身上的虱子进化来的。

4·So biologists have long been puzzled over the fact that the human head louse is a sister species to the chimpanzee louse, but the pubic louse is closely related to the gorilla louse.

所以生物学家长期为此困惑：为什么人类的头虱是黑猩猩虱子的近亲。而阴虱却是大猩猩虱子的近亲。

5·In 2003, Mark Stoneking, a geneticist at the Max Planck Institute in Leipzig, Germany, estimated from DNA differences that the body louse evolved from the head louse about 107,000 years ago.

2003年，普朗克学院的基因学家斯通金估算体虱大概在十万七千年前于头虱分叉。