I guess this is some kind of topical question being asked by a member of the contemporary human species with the benefit of speech, language, writing, and several thousand years of civilization. The latter is in the benefit column, right? :-)

Who knows what wiped out the Neanderthals, since it could have been any number of occurrences over the latest geologic period? Was it the benefit of early experiments organizing early civilizations as opposed to nomadic tribalism? (like, my tribe is bigger than yours' kind of thing) We probably don't know a lot about prehistory, where knowledge of the copulation question among the human species probably resides.

This question could be the luck of the evolutionary draw as homo sapiens supposedly came close to being wiped out due to natural disaster occurrences during various epochs of prehistory.

We might conjecture some behavior traits of early humanoids, they probably weren't into waxing and stuff like that. :-)