Women are very attracted to a low voice because it's linked to testosterone, which for millions of years was a sign that men had very good spacial skills and would have been very good at hunting and finding their way back home.

It certainly would have been adaptive for ancestral man to have a chubby wife during stressful times of famine. Not only would she have had more calories to burn, and thus more energy and endurance, but since fat stores estrogen, she would have remained fertile for longer.

Like most animals, we're wired to associate height with power.

Natural beauty really entices men. They will tell you this time and time again, and studies consistently prove it.

Women apparently are quite drawn to men who have differences rather than similarities in their histocompatibility system. They pick it up by smell, and they can pick it up from kissing.

Men tend to be hierarchical, but women are driven to make lateral connections so they can cooperate.

Saliva has testosterone and estrogen. When you kiss, you're having a chemical experience.