Amity-enmity complex

The amity-enmity complex is a theory the anatomist and anthropologist Sir Arthur Keith proposed in his 1948 book A New Theory of Human Evolution, arguing that human beings evolved a dual moral instinct: warmth, trust and cooperation toward the members of one's own group, and suspicion or open hostility toward outsiders. Keith held that conscience itself evolved with this double purpose, to protect and support friends and to hate and fight enemies, and that showing generosity toward rivals would have been a competitive disadvantage in the evolutionary struggle between early human groups. Building on earlier ideas about tribalism from Charles Darwin, Alfred Russel Wallace and Herbert Spencer, Keith argued that patriotism, in-group morality and nationalism are all evolved expressions of the same underlying complex, one that holds a community together but grows harder to sustain as that community expands past the scale of a small tribe, a strain he thought mass communication might offset even at populations of a hundred million or more. He controversially framed racial segregation, apartheid, caste systems and religious division as expressions of this same innate in-group and out-group instinct rather than as separate social problems.