hamilton's rule states or implies that altruistic behavior is favored when the benefit to the receiver, weighted by its relationship to the altruist, is greater than the cost to the altruist. altruistic behavior toward a full sibling is more beneficial than altruistic behavior to a child. selection will not favor an altruistic behavior if it causes the altruist to die. altruistic behavior must be reciprocal to be favored by natural selection.