Kevin Hsiung

Selection acts differently on males and females and drives their phenotypic dissimilarities. Most research has focused on males and how sexual selection shapes their ornaments and weaponry in the context of gaining access to female mates. This is not least due to the fact that humans, as most other vertebrates, show "conventional", "Darwinian" sex roles concentrating our perception on competitive males and caring mothers.

The mechanisms of sex determination are diverse despite their unifying function in defining male and female sex within a species. They range from an array of environmental factors over different genetic sex determination systems to a complex interplay of extrinsic and intrinsic factors. These mechanisms are ultra-conserved in some organismal groups (e.g. all mammals share the same sex chromosomal system), however, in other groups even sister species vary in their way how sex is determined.