"How does the capacity for low mood give a selective advantage?"

"How does the capacity for low mood give a selective advantage?"
Links:
[1] http://www.edge.org/annual-question/what-questions-are-you-asking-yourself
[2] http://www.edge.org/inthenews/what-questions-are-you-asking-yourself
[3] http://www.edge.org/contributors/what-questions-are-you-asking-yourself
[4] http://www.edge.org/responses/what-questions-are-you-asking-yourself
[5] http://www.edge.org/print/response-detail/11546
[6] http://www.edge.org/memberbio/randolph_nesse