Penis is a competitive beast

Scientists believe the shape of the penis may have evolved to help men remove the semen of love rivals during sex.

Tests led a team of US researchers, headed by Professor Gordon Gallup, to conclude that the penis acts as a "semen displacement device" and its shape has evolved in part to displace another man's semen.

The team from the State University of New York believe the thrust of the penis during sex may help to clear a woman's reproductive system of a previous lover's semen.

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