The bigger the brain, the smaller the

Male bats with developed brains are quite humble. The researchers say this correlation is because both agencies consume a lot of energy to develop, so forcing species to find the optimal balance.

The analysis of 334 bats was found in species where females or promiscuous females have large testicles but have relatively small brains. In species where children are faithful, the situation is the opposite. Male sympathy has no effect on brain or testicular size.

Both brain tissue and sperm cells require a lot of metabolic energy to grow and maintain. Different species have different priorities in developing one or the other, all to help them produce more children.

" Bat's testicle volume accounts for 0.12% to 8.4% of body mass - exceeding the level of any mammal. The primate's testicle volume accounts for 0.02-0. , 75% of body weight , "said Scott Pitnick at Syracuse University, USA.

Energy efficiency is important for bats, Pitnick said: "They are small creatures that fly over a wide surface, they need to fly a lot, especially during the breeding season."

Initially, Pitnick and his colleagues surmised that in species with a common female, males need larger brains to avoid being " horned ". So they were surprised to find the opposite. " Maybe fidelity costs more neurons ."

Harry Moore, a researcher at the University of Sheffield, UK, said testicle size is often related to sperm count. " In species with diverse females, males have to compete for fertilization of her eggs and therefore need to produce more sperm. This is especially true when females store sperm for several months. ".

MT ( Newscientist )