The laboratory-grown mini ‘brains’ of humans and monkeys reveal why man has grown so much

Using laboratory-grown mini-brains, scientists have figured out why humans have bigger brains than monkeys.

About 5 to 8 million years ago people and monkeys they parted from a common ancestor. Some time after that, humans began to evolve to have bigger brains; now human brain are about three times the brain size of chimpanzees, our closest living relatives.