The Coevolution of Altruism, Parochialism and War - Santa Fe Institute

Why humans
escaped the
evolutionary fate
of an altruistic trait
A N
A b-c -c
N b 0
• The degree of positive assortment is P(A|A) - P(A|N)
• How different groups must be in order for the As to survive
shown in the figure = c/b namely, the ratio of the individual
costs to the group benefits.
•Those who put group selection in the dog house believed
that between group genetic differences, namely P(A|A) -
P(A|N) were much too small small, maybe on the order of
0.02 (requiring b to be 50 times c!)
• Others also thought that b/c would be quite small (2, 4, etc)