Wild chickens bred to be unafraid of humans have smaller brains

Junglefowl (aka wild chickens) are wisely fearful of humans. Researchers from Linköping University were able to catch some junglefowl and selectively breed the ones who showed the least fear of humans. After 10 generations, "the offspring acquired smaller brains and found it easier to become accustomed to frightening but non-hazardous events."

"We believe that the ability to become accustomed rapidly is beneficial for the birds that are to live among humans, where events that are unknown and frightening, but not dangerous, are part of everyday life," says Rebecca Katajamaa, doctoral student in the Department of Physics, Chemistry and Biology at Linköping University.

The researchers also investigated whether the birds differed in the ability to learn to associate two things with each other, such as coupling a certain pattern with food. This process is known as "associative learning." However, they found no differences between the two groups.

It is not possible to say whether the differences in behaviour shown in the study are directly connected with the differences in brain size and composition. The researchers plan to investigate this in more detail.

"Our study not only sheds light on a possible process by which chickens — and possibly other species — become domesticated. It may also give new insight into how the structure of the brain is connected with differences in behaviour between individuals and species," says Per Jensen, professor in the Department of Physics, Chemistry and Biology at Linköping University.