The Trobriand Islanders of the Melanesian region, as well as many other cultures in the Australian and New Guinea regions, had a believe that there was no cause and effect relationship between sexual intercourse and pregnancy. As detailed in this monograph, the Trobrianders believed that the Baloma, the spirits of the dead, would return from the afterlife and impregnate women when they bathed in the lagoon, thus reincarnating the dead ancestor. This often cited monograph by one of the foundations of modern ethnography is a classic of the field. Malinowski makes a breakhrough observation this is not just a quaint lack of scientific understanding by 'natives'; it is part of an entire cultural complex that makes as much sense as any other, relatively speaking.
