Risk taking and the menstrual cycle

From the Economic Logic blog comes this piece on Risk taking and the menstrual cycle:

Matthew Pearson and Burkhard Schipper asked an unusual question to the female participants in an otherwise standard auction experiment: what stage of your menstrual cycle are you in? It turns out the answer can explain bidding behavior: while otherwise indistinguishable from men, women in their menstrual and premenstrual phase bid significantly higher, thus exhibiting more risk taking.

If correct, there is an obvious question, Why such behaviour?

Pearson and Schipper argue this can be explained by biology and evolution. This is when women are most likely to be fertile and take risks to increase the probability to procreate.