Your brain is probably filled with useless trivia that you can show off by doing quizzes like this. But scientifically, about 75% of the brain is made up of what?

Because it's mostly water, the brain is very susceptible to dehydration, which can cause changes in memory and ability to pay attention. Of course, that's nothing compared to the lungs, which are almost 83% water.

Asked by Tom Cohen · Last updated 5 years ago · 37.7K views