Question: What is the main purpose of a brain and why do people remember stuff?

David Ho answered on 12 Nov 2018:

I’m no expert on this (I study particles much smaller than a brain!) but I’ll tell you what I know. The brain is the control centre of the body — it takes information from the outside world and uses this information to carry out a response. For animals to take in complicated information and carry out complicated responses they need a brain.

As far as I know we still don’t know a lot about how memory works. But the answer to almost all “why” questions about living things is “it makes us more likely to survive”. If we can remember a situation we’ve been in, we can react more quickly if we encounter the same situation again. So if we’ve been stung by a nettle before, we remember what it was like so we don’t need to touch it again to find out if it’s safe to touch! Through the process of evolution living things develop features that make them more likely to survive — I would guess that memory is one of these.