Us Vs Them

For more than two million years, our human ancestors lived in small groups that they considered their own. They created a demarcation of us vs them, as people cared and cooperated with people in their own tribe while fearing and aggressing people outside their band. 

This ancient divide is now amplified, and larger groups of 'us' are now in constant conflict with the other groups of 'them', partly due to the advent of technology in the past hundred years.