Lefties have been bouncing back in recent decades, following a decline in the beginning of the 20th century, a new study shows.

While lefties currently make up about 11 percent of the population, earlier studies found only 3 percent of those born in 1900 were left-handed. These claims led Ian Christopher McManus of the University College London and his colleagues to learn more about this change.

“Left-handedness is important because more than 10 percent of people have their brains organized in a qualitatively different way to other people,” McManus said. “That has to be interesting. When the rate of a [variable trait] changes, then there have to be causes, and they are interesting as well.”