Abstract

In order for the process of hominization to continue, with its prolonged and extreme period of juvenile defencelessness, it was necessary, or at least convenient, for males to more actively participate in the care of females and offspring. This necessity, together with the abrupt loss of hominid sexual dimorphism starting with Homo ergaster (more than 1.5 million years ago) suggests to the authors that our ancestor’s sexuality might have evolved around the same time from an earlier state of polygamy to monogamy. Taking into consideration our meagre dimorphism, small relative testicular size, and interest for living in partnerships, monogamy may still persist in modern Homo sapiens. This theory would allow for new perspectives regarding the complex suite of enigmatic emotions have plagued modern humans since our beginnings.