Dawkins’ The Selfish Gene goes into this in greater detail. Many species are hardwired to be willing to sacrifice their own lives for the survival of their kin. Basically, genes that code for protective and social behaviors might result in any given individual more likely to die before reproducing, but makes that individual’s close genetic kin more likely to survive to reproduction such that a particular group/pod/clan/flock is much more likely to persist over generations.

The extreme example is ants and bees, where most of the workers we see biologically cannot reproduce and are dead ends as individuals. But they work for the hive/colony, and the reproducing queen is the center of that reproductive strategy.

You see it with a lot of animals, especially those wired to be social.