Baculum
Most male mammals have bones in their penises. It aids sexual reproduction by maintaining stiffness during sexual penetration.
But not humans wherein the rigidity of the erection is provided entirely through blood pressure in the corpora cavernosa.
Richard Hawkins proposed “honest advertising” as the evolutionary explanation for the loss of the baculum in humans.
The hypothesis is that if erection failure is a sensitive early warning of ill health (physical or mental), females could have gauged the health of a potential mate based on his ability to achieve erection without the support of a baculum.
Extrapolating, that hypothesis assumes that a relationship focused on reproduction starts with test sex.
So what was the church on about eh?
offshore westerly 