Clear evidence of women's promiscuity throughout evolutionary history is in the size and shape of men's genitals and what men do with them.

the human male during copulation engages in repeated thrusting motions before he ejaculates. The combined effect of the particular shape of the penis glans and the repeated thrusting motions during intercourse is to draw foreign semen back away from the cervix. If a female copulated with more than one male within a short period of time, this would allow subsequent males to scoop out semen left by others before ejaculating. In other words, the human penis is a semen displacement device.

It is designed and used to remove other men's semen from the cervix before the man ejaculates.

If women did not engage in extensive extra-pair copulations throughout human evolutionary history, then the human penis would not be shaped as it is (like a wedge or scoop), and the human male would not engage in repeated thrusting motions during intercourse before ejaculating. Clear evidence of women's promiscuity throughout evolutionary history is in the size and shape of men's genitals and what men do with them.