1. Women Are From Earth, Men Are From Earth

2. Thesis Different patterns of behavior in men and women can be explained by the same principle: natural selection.

3. The Basics of Natural Selection Evolution refers to changes in organisms over generations Evolution is driven by the process of natural selection

4. The Basics of Natural Selection There is variability across individuals in any generation of organisms Some of the variation is caused by genetic differences Characteristics vary in their adaptive value in a particular environment

5. The Basics of Natural Selection Genes causing more adaptive traits are more likely to be passed to the next generation Over a large number of generations, more adaptive traits become more common in the population

6. Just to be clear…. Current adaptive value is not the issue Evolution is not random Complex functions can develop gradually We did not evolve from current species An evolutionary explanation for something does not provide moral justification

7. Selection Pressures The evolutionary psychology perspective predicts that different behavior patterns should have evolved in the presence of differing selection pressures Selection pressures were similar in most areas for men and women, but different in others, particularly for mating-related behaviors

8. Selection Pressures for Women Find a reproductive partner who will provide resources to help ensure the survival (and eventual reproduction) of the offspring

9. Selection Pressures for Men Maximize the chances that any resources provided are supporting the man’s own offspring, not those of a rival

10. Example 1: Jealousy Women should be more distressed by emotional infidelity Men should be more distressed by sexual infidelity Research confirms this pattern across cultures

11. Example 2: Commitment Skepticism Women should tend to underestimate how committed a man is to a long-term relationship High cost for a woman of engaging in sex too early in a relationship Women who are the recipients of courtship displays (e.g., flowers) rate their importance lower than do observers of the displays

12. Example 3: Sexual Overperception Bias Men should tend to overestimate the desire of a woman to engage in sex High cost of missed opportunities Men tend to misread gestures such as smiles and touches as indicating sexual interest But this does not occur when the woman is not a possible reproductive partner

13. A Few Caveats As with most research, these findings are probabilistic The fact that there are genetic influences on behavior does not mean that people have no choice Finding an explanation for a behavior does not morally justify the behavior