I remember that to be false, and just looking it up online: In prehistoric times, night owls could keep watch and protect their tribes from nocturnal predators

I remember that to be false, and just looking it up online: In prehistoric times, night owls could keep watch and protect their tribes from nocturnal predators, and in ancient times, they could protect their cities from conquerors trying to sneak in at night. There was an evolutionary benefit to having both morning larks and night owls within our species.