Bronislaw Malinowski was a phenomenal and well-regarded anthropologist, doing research throughout Africa and the Pacific Ocean. His contributions deal in large part with the sexual mores and taboos of society and whether they are inherent or learned behaviors. His belief was that these behaviors are not inborn but are more often than not learned, and he even believed he found a society that had yet to discover the link between sex and childbearing (though this is disputed).
Perhaps the greatest achievement, however, was simply the view he took of anthropology, as opposed to his actual discoveries. Malinowski is credited with a much more human-centered approach to anthropology, and he attempted in large part to understand the individual characteristics and experiences of people in cultures. This ground-level view of cultures has shaped the practices in anthropology since his time and has led to a great number of other discoveries and theories.