The evolution of sex contains two related, yet distinct, themes: its origin and its maintenance. The origin of sexual reproduction in prokaryotes is around 2 billion years ago (Gya) when bacteria started exchanging genes via the processes of conjugation, transformation, and transduction.
The evolution of sex (and its accompanying reproductive capability) is not a favorite topic of discussion in most evolutionary circles, because no matter how many theories evolutionists conjure up (and there are several), they still must surmount the enormous hurdle of explaining the origin of the first fully functional female and the first fully functional male necessary to begin the process.
Freud was aware of Darwin's theory. Evolution acts strongly on anything related to reproduction, so sex and everything connected with it is important in animal behavior. Survival hangs in the balance. This lends a general plausibility to the idea that sexual issues are important and psychologically potent.
Evolutionary Theory Evolutionary theory is a broad based view that certain types of sexual behavior are genetic and passed down from one generation to another through the process of evolution, natural sex, and survival. This theory separates into two types to explain violent crime and sexual.
Theories of the Evolution of Sexual Dimorphism. Sexual dimorphism refers to differences between individuals of differing gender in traits other than gender itself (Chap. 1, Table 1), and can be found in both primary and secondary sex characters. Primary sex characters are traits, such as gonads and copulatory organs, Cited by: 66.