What about this from BBC News April 26/06... more important info you can't live without!
Fertility sparks 'male rivalry'
Researcher Rob Burriss said many previous studies show that
women's preferences for male physical appearance change according to their fertility status. Whether they consciously know it or not women do tend to have affairs with dominant males during their most fertile phase
Dr George Fieldman Psychology expert
He said during the fertile stage of their menstrual cycle they are more likely to be attracted to, and have an affair with, a masculine-looking man.
"Earlier research has shown that women are more interested in men who have a high testosterone face type - a jaw line like Arnold Schwarzenegger for example - for a short term relationship.
"They have better genes and are more likely to have strong children.
"This is because high testosterone levels create stronger immune systems which make them more resistant to disease."
He surmised that men with fertile partners were sub-consciously aware of this preference change from their female partner and were reacting to it. Those with partners in the most fertile stage of their menstrual cycle were more able to spot classic masculine face types - ie men with strong jaw lines, thinner lips and smaller eyes and recognize them as potential rivals.