Some of these questions can be answered by studying the brains of other animals like mice, for example.

But this isn't possible for other phenomena that are unique to human brains.

Researchers are now growing hundreds of tiny human brains in labs, in an attempt to understand what gives us unique disorders like autism and schizophrenia - and the method they use to create these brains is surprisingly simple.

Scientists across the world are developing cerebral organoids, or mini brains, to solve a variety of problems.

Many of these groups are trying to understand other complex neurological diseases that are unique to humans, like autism and schizophrenia.