Men and attractive women
We are descended from the humans with the most children – not from those with the "enough" of today's world. Thousands of years ago the relentless drive amongst men was to procreate. We are descended from those who were most successful – and our genetic framework still carries the imprint, a memory from this past. Today we see echoes of this driver in many ways. What man does not look up at once as a pretty arm, tummy or leg goes by?
He may feel a pang of guilt towards the girl on his own arm. As an unaware "lad", he may respond to the immediate attraction by feeling the need to "play the field". His girlfriend may feel annoyed at his eyes constantly following the passing women and see them as a never–ending stream of competition. Neither needs to feel like this. Once they understand that he is responding instinctively to his ancient biological drivers they can grow into an adult, more rational awareness. He will realise he has no intention of doing anything about his flickering gaze. He will know he is only momentarily and superficially out of control. He will have no need to build this almost capricious head–turning into the destructive need to play the field and perhaps destroy a developing and valuable relationship with someone he already knows and likes. However irritating this habit of men, she can know it is relatively harmless. She can just smile at the throwback to the caveman who is on her arm — at least he is alive and well and in no need of an eye check!