religion as a biological organ . . .

Man is always concerned about his destiny—that is to say, his position and rôle in the universe, and how he is to maintain that position and fulfill that rôle. All societies of man developed some sort of organs for coping with this problem—organs for orientating their ideas and emotions and for constructing attitudes of mind and patterns of belief and behavior in relation to their conception of their destiny. All of the social organs concerned with destiny can, I think, properly he included under the head of religions. Even if some of them are exceedingly primitive and consist of little but magic rituals, while others are highly developed and claimed to be entirely rational, they are all, from Haitian voodoo to Roman Catholicism, from neolithic fertility religions to Marxist Communism, concerned with the same general function. In the same sort of way, the tube-feet of a starfish, the legs of a horse, the pseudopods of an amoeba, and the wings of a bird, though profoundly different organs from each other, are all animal organs concerned with the same general function of locomotion.

Julian Huxley
Religion Without Revelation
1957