There are many things that make humans a unique species, but a couple stand out. One is our mind, the other our brain.

The human mind can carry out cognitive tasks that other animals cannot, like using language, envisioning the distant future and inferring what other people are thinking.

The human brain is exceptional, too. At three pounds, it is gigantic relative to our body size. Our closest living relatives, chimpanzees, have brains that are only a third as big.

Image: Viktor Koen / NY Times