• Question from:Jonathan

I read in a stats book (Field, 2011) that the reason why the penis in humans has a bell at the end with a ridge is because the idea is that if someone else has been insider their mate (you know what I mean) then this acts as a scoop to pull out existing sperm so that there isn't competition with the latter man's sperm.

Surely this can't be true - is it?

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  • University of Bristol
  • Posts: 2,462

the refrence he refers to is:
http://www.sciencedirect.com/science/ar … 3803000163

Abstract
Inanimate models were used to assess the possibility that certain features of the human penis evolved to displace semen left by other males in the female reproductive tract. Displacement of artificial semen in simulated vaginas varied as a function of glans/coronal ridge morphology, semen viscosity, and depth of thrusting. Results obtained by modifying an artificial penis suggest that the coronal ridge is an important morphological feature mediating semen displacement. Consistent with the view of the human penis as a semen displacement device, two surveys of college students showed that sexual intercourse often involved deeper and more vigorous penile thrusting following periods of separation or in response to allegations of female infidelity.


I have to say that the evidence for their hypothesis is in my view weak at best!

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  • University of Exeter
  • Posts: 576

"this acts as a scoop to pull out existing sperm so that there isn't competition with the latter man's sperm"



Just to add that while this may or may not be important in the evolution of human penis shape, sperm competition is widely hypothesised to have influenced the evolution of penis morphology across many animal taxa.