Humans are a highly social species
Perceiving, understanding and interacting with other people is at the core of what it means to be human, and brain regions supporting different aspects of social cognition take up a large area of the cortex.
To Learn More:
1. Watch two TED talks by two of the most brilliant neuroscientists alive today that illuminate this idea with specific examples:
Rebecca Saxe’s TED talk on a brain region specialized for thinking about what other people are thinking, Rebecca Saxe: How Brains Make Moral Judgements
Doris Tsao’s TED talk about brain regions in monkeys that are specialized for perceiving faces, http://tedxcaltech.caltech.edu/content/doris-tsao
2. Even young infats spontaneously help strangers. To see videos documenting this behavior and scientific papers, go here: http://www.eva.mpg.de/psycho/study-videos.php and here https://software.rc.fas.harvard.edu/lds/research/warneken/video-clips/
3. Many people have written eloquently about the idea that the need to understand other people was a major driver of the evolution of the human brain. Here are just a few:
Byrne, R. W., & Whiten, A. (1989). Machiavellian Intelligence: Social Expertise And The Evolution Of Intellect In Monkeys, Apes, And Humans (Oxford Science. Brothers, L., & Ring, B. (1992).
A neuroethological framework for the representation of minds. Journal of cognitive neuroscience, 4(2), 107-118. Dunbar, R. I. (1998).
The social brain hypothesis. Brain, 9(10), 178-190. Hrdy, S. B. (2009).
Mothers and others: The evolutionary origins of mutual understanding. Harvard University Press.