These Ants Shrink Their Brains for a Chance to Become Queen - The New York Times

In a study, published Wednesday in the journal Proceedings of the Royal Society B, scientists found that Indian jumping ants can shrink their brains by nearly 20 percent and unshrink them in a matter of weeks.

Although other insects, including honeybees, have been known to possess the ability to increase their brain size, the Indian jumping ant is the first insect known to be capable of both increases and decreases in brain size.

Like most ant colonies, those of Indian jumping ants consist of a queen, males for reproduction and an all-female worker class.

However, Indian jumping ants are a species that allow worker ants to compete for a chance to become royalty.

Although worker ants and gamergates are similar in size, their internal anatomy is vastly different.

Penick and his colleagues compared the internal anatomy of workers and gamergates and found that becoming a gamergate not only caused worker ants’ ovaries to balloon to five times their normal size, but it also caused their brains to shrink by roughly 20 percent.

“Worker ants need a large brain to deal with these cognitive tasks, but gamergates don’t need to think that much,” he said.

The researchers believe that these ants shrink their brains to conserve energy, a behavior also observed in Etruscan shrews, a tiny mammal that sheds brain size in winter to keep other parts of its body warm.

Traniello, who studies brain evolution in other ant species, believes that when female Indian jumping ants transform into gamergates, most of the energy that was once spent on the brain gets diverted to parts of the body that are responsible for reproduction.