According to reports in The Telegraph, the energy and drive that originally focused humans on basic survival, such as food and shelter, have become unfocused and secondary in the 21st century.
This is because people are largely provided for, leaving the motivations that fuel basic survival without an appropriate outlet.
Humans evolved to become angry in certain situations because the emotion motivates us to want things. For example, hunger makes us angry by raising our serotonin levels, prompting us to look for food.
Anger also played an important role in helping early humans live together in social groups, by warning individuals when their behaviour was upsetting others.
'The red mist of rage helped our ancestors survive,' Dr Mann claimed