Some stories really ache for commentary. I will leave that up to you, my fine Blenders…

For some male bats, sexual prowess comes with a price — smaller brains. A research team led by Syracuse University biologist Scott Pitnick found that in bat species where the females are promiscuous, the males boasting the largest testicles also had the smallest brains. Conversely, where the females were faithful, the males had smaller testes and larger brains.

“It turns out size does matter,” said Pitnick, whose findings were published in December in “Proceedings of the Royal Society: Biological Science,” an online journal.

The study offers evidence that males — at least in some species — make an evolutionary trade-off between intelligence and sexual prowess, said David Hoskens, a biologist at the Centre for Ecology and Conservation at the University of Exeter in England and a leading authority on bats’ mating behavior.

[QUOTE OF THE DAY] “Bats invest an enormous amount in testis, and the investment has to come from somewhere. There are no free lunches,” said Hoskens, who did not participate in the study.

…”If female bats mate with more than one male, a sperm competition begins,” Pitnick said. “The male who ejaculates the greatest number of sperm wins the game, and hence many bats have evolved outrageously big testes.”

…Large brains, meanwhile, are metabolically costly to develop and maintain. Pitnick’s research suggested that in those bat species with promiscuous females, the male’s body used more of its energy to enhance the testes — giving it the greater adaptive advantage — and lacked the energy it needed to further develop the brain.

Hat tip, Paul.