Who do men and women find attractive in the opposite sex?

Erica Tempesta reports at Dailymail.com that new research show that men find women in their early twenties the most attractive. This was true for all ages of men up to age fifty. Why didn't they study men over age fifty? Do they assume it is irrelevant who we find attractive?

...women like men to be slightly older than them until they hit their 30s. Then they become interested in men who are their own age or slightly younger. By their 40s, women are most attracted to men who are two to eight years younger than they are.

Read more here.