Sex Determination across Evolution: Connecting the Dots.

The article focuses on the discovery of the key sex-determining genes. The identification of the Hox genes in Drosophila melanogaster and the subsequent discovery of their conservation and similar expression in different Metazoans led to the revolutionary realization that many of the mechanisms critical to basic animal development have been conserved across more than 500 million years of evolution. The variety of primary sex determination cues was appreciated long before the advent of molecular genetics.