On the whole, males are more risk taking than females (just look at young men's insurance costs).

This is true outside our species, as well as within. In most species, including our ancestors, it was the aggressive males that acquired the most resources that contributed the most genetically to the next generation (interestingly a good percentage aggressive males also tended to die without reproducing, but of the males who reproduced, they made up the biggest share). Aggression does not pay off the same way for mammalian females. With substantial time and resource constraints, a conservative strategy was far more effective. Get going early and be sure you remain alive to care for the young, almost the opposite of the optimal strategy for the males.