Further, regard our closest evolutionary relatives. Chimpanzees sometimes go to war with other groups of chimpanzees. When they do the males of the weaker group flee. They show no propensity for self-sacrifice or taking risk for a fellow of their group.

Self-sacrifice outside of perhaps a parent defending its young does not appear in other species.

As no particular genetic adaptation appears for self-sacrifice, I suggest that it follows that the human brain and its intellect — operating at either a conscious or unconsciously level — has come to understand self-sacrifice as a preservation of a group’s or tribe’s or family’s gene pool. Self-sacrifice solves a problem.

Intellect, at all stages of cultural development, gets employed to solve problems. Nothing else ever has.