UK: Women play hard to get to find out how helpful men will be, scientists say

Article here. Excerpt:

'Researchers believe that the female of any species employs the technique so that men can prove themselves more worthy than their rivals.

But it only works where there are a large number of males to choose from and where there is a mixture of different types of men.
...
Professor John McNamara, co-author of the paper, came up with the conclusions after crunching the data into a mathematical model.

He believes coyness and helpfulness tend to encourage each other - although some males have learned to cheat.

"The more coy females are, the more helpful men will be; and the more men around, the more coy women are," he said.'