What is it about?

Why the sexual climax, in humans, results in a pleasurable experience remains an important biological question. Analysis of evolutionary traits in numerous Vertebrates suggests that orgasm evolved through three phylogenetic stages during the transition from external to viviparity.

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Why is it important?

Although the analysis of natural history suggests that orgasm comes from the discharge mechanisms of gametes, its current evolutionary significance in vertebrates would rather derive from postcopulatory selective mechanisms. Orgasm has its origin in the evolution of fertilization patterns, and has evolved to stimulate sexual activity because the evolutionary transition from external fertilization to viviparity has been accompanied with a lessening in reproductive rates. Nevertheless, the orgasmic signal entails a positive experience, which emphasises the success of the relationship. Clearly, females can manipulate male behaviour to bias paternity. Thus, orgasm could find its current evolutionary significance in the preference of an unrelated sexual partner, in species using internal fertilisation. Because orgasm could promote a better choice of partner, female orgasm may have evolved as a postcopulatory selection tactic by which females can increase their control of mates. In any case, orgasm has naturally a behavioural reinforcement effect of reproductive activities.


The question of the function of orgasm opens up many unresolved issues, both about the role of the different fluids involved and about the diversity of sexual behaviour. The transition from internal fertilization to viviparity could hence be the most remarkable step in the evolution of the orgasm. Moreover, significant associations between sexual characters, intromittent organs and lineage-specific diversification rates showed that viviparity as a new reproductive life-history trait has boosted evolutionary diversification

Thierry Lodé
Universite de Rennes 1

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This page is a summary of: A brief natural history of the orgasm, Frontiers in Life Science, September 2019, Taylor & Francis,
DOI: 10.1080/21553769.2019.1664642.
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