In recent years biologists have sought to show how human behaviour, culture and civilisation are reflected in our genes - and to show how these evolved.
For decades, the prevalent theory has relied on what's called "kin selection".
The idea is that because human beings lived in family groups, they developed selfless or altruistic behaviour.
Now, one of the leading thinkers in the field, Professor Edward Wilson, has said that is wrong.
The Today programme's Sanchia Berg met him at Harvard University where he explained his rival theory.
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