Talk about Trade-offs

http://www.foxnews.com/story/0,2933,178234,00.html

the particularly insightful part:

In the study, Pitnick and colleagues analyzed 334 species of bats and found
that in species with promiscuous females, the males had evolved larger
testes but had relatively small brains.In species where the females were
faithful to their mates, the correlation was reversed. The study also showed
that male fidelity appeared to have no influence over testes or brain
size.

Man.. it must be tough to make a choice like that:

Behind Door Number 1

Behind Door Number 2