Complex sentence: There is also evidence that both intra-group and inter-group violence were much more prevalent in the recent past and in tribal societies which suggests that tendencies to use violence in order to achieve goals are affected by society.
Split into simpler sentences: There is also evidence that both intra-group and inter-group violence were much more prevalent in the recent past and in tribal societies. This suggests that tendencies to use violence in order to achieve goals are affected by society.