It seems as if we might be! A team of Swiss scientists has grown artificial human, chimp and macaque mini-brains from stem cells in a lab. These are miniature cell collections that allow for the study of brain development.
Good news: each of the brains initially developed at the same speed.
Bad news: once development moved on to the cells specializing in different neuron types, the macaque took the lead, the monkey followed, and we were stuck in bronze medal position!
Get-out clause: it’s reckoned that the slow development might be due to a human having to develop a larger and more complex brain.
So it seems that size is important – allegedly!
Source: https://www.bbc.co.uk/news/science-environment-50055547
