Size, does it matter?

A study with mammals proves that the group with the promiscuous females has males boasting the biggest testicles, but had the smallest brains. On the contrary, when the females were faithful, the males had smaller testes and larger brains.
A research study was done at Syracuse University biologist Scott Pitnick on bats. They are the second largest group of mammals (behind rodents) with about 1,000 known species.

Men, I know women say all the time that size doesn’t matter, but it does matter, at least in this study!

“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 Center for Ecology and Conservation at the University of Exeter in England and a leading authority on bats' mating behavior.”

Pitnick's team looked at 334 species of bats and found a convincing contrast in testes size. In species with monogamous females, males had testes starting at 0.11 percent of their body weight and ranging up to 1.4 percent. But in species where the females had a large number of mates, Pitnick found testes ranged from 0.6 percent to 8.5 percent of the males' mass (in the Rafinesque's big-eared bat).

"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. Promiscuity is known to make a difference in testicle size in some other mammals. For example, chimpanzees are promiscuous and have testicles that are many times larger than those of gorillas, in which a single dominant male has exclusive access to a harem of females.”

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.

The study found that in more monogamous species, the average male brain size was about 2.6 percent of body weight, while in promiscuous species, the average size dipped to 1.9 percent.

To my knowledge, there has not been any human studies to support this evidence. So, gentlemen....size doesn't matter....at least in this case ;)