Human brains evolved over the last four million years in response to the interaction between environmental challenges and behaviours that enabled us to overcome these challenges. But the future of the brain may be more directly in human hands.

Our ancestors became more successful at ensuring their survival with greater behavioural complexity over time. So their bodies grew in size because of more efficient ways of obtaining foods. And the advantages of greater body size and strength provided security from predator attacks.

As our bodies were growing taller – from about 1.2 metres 3.5 million years ago to about 1.7 metres at the end of the Ice Age some 10,000 years ago, brain expansion followed. This is not surprising because bigger bodies need more nerve cells to control them. But this part may come as a surprise – during the last few thousand years, especially from the time the oldest civilisations arose (about 5,000 years ago) our brains became smaller (yes, smaller!) by about 10%

Read more at The Conversation.