Assigning humans to discrete categories based on common ancestry is known as and was once a main way that scientists studied human biological diversity.

Racial classification

Explanation: Racial classification can be defined as the way humans are classified based on their physical and social traits which they have such as how they look, their skin color, hair texture, the native languages they speak.

Scientists used racial classification to learn how unique and different humans are.

you did not attach the discourse, but i assume it to be the discourse on the origin and basis of inequality among men (the original titile in french is: "discours sur l'origine et les fondements de l'inégalité parmi les hommes"), also know as "second discourse". in this discourse, jean-jacques rousseau emphasizes that private property is the basis of all inequalities.

therefore, what enabled the old regime to maintain as long as it did was private property.

the answer to the blank provided is “an autosomal gene that is required for the expression of genes on the x chromosome”.

testis-determining factor, abbreviated as td, which is more popularly known as sex-determining region y or sry protein, is a dna-binding protein or  gene-regulatory protein/transcription factor, encoded by the  sry gene. it is the gene responsible for the initiation of male gender determination in humans.