But evolution happens whether or not the creatures in question understand evolution or even heredity. (In fact, if they know nothing about it, that makes it ea

But evolution happens whether or not the creatures in question understand evolution or even heredity. (In fact, if they know nothing about it, that makes it easier for evolution to do its thing without interference.) The legendary "shape of the human penis designed to pull out the sperm of other men who have recently had sex with the same woman", if it worked, would do very well evolutionarily in the first kind of culture you describe. Likewise, if teenagers being awake at odd hours does cause them to have sex and reproduce more often, then (assuming the tribe will take care of the children) the genes that cause them to do this will be selected for, whether or not the teenagers or the adults realize it.