PERSONALITY is pointless unless someone notices you have it.

Both humans and animals have personalities – consistent behavioural patterns – but how did they evolve? To find out, Max Wolf of the Max Planck Institute for Human Development in Berlin, Germany, created simple simulated animals with personalities that were either consistently aggressive or meek, or flipped between the two.

They were pitted against each other in repeated contests designed to be representative of many seen in the real world – for instance when an individual is defending its territory.

All three animal types did equally well until Wolf introduced a new one that …