The 10% number is pure nonsense. Always has been. Always will be. All humans use all of their brains.

The question that should be asked is "to do what?"

Some use them to guess who the survivor will be on a reality show. Some use them to remember meaningless metrics about who pitched a perfect no-hitter in a baseball game 20 years earlier. And some explore the cosmos and develop cures for scourges like polio.

As with many things ... stupid people are concerned with quantity rather than quality.

DA Morgan