September 22, 2021

I, Science

The science magazine of Imperial College

Evolutionarily advantageous or just a bloody good bonus?

The debate of the origins of the female orgasm in humans has been of great interest to both the scientific community and the world at large for centuries, yet the debate is still not concluded based on current evidence.  In addition certain standpoints, whilst seeming scientifically savvy, have sparked controversy because of their implications to feminism: the idea that the female orgasm is simply the by-product of physiology, for example, has been argued to devalue its psychosocial value. Indeed Freud and others referred and refer to women incapable of achieving orgasm as being “dysfunctional” and “neurotic”. This illustrates the sensitivity that must be taken when discussing this delicate matter.

It is necessary to define what a female orgasm is. It is a peak of intense pleasure, whereby a woman undergoes involuntary pelvic, uterine, vaginal and anal contractions. In addition an altered state of consciousness is achieved due to the closing of emotion centres in the brain, which in studies has been used as a measure to test the authenticity of orgasm. The involuntary contractions associated with genuine orgasm can also be determined by the frequency of muscular contractions, measured from the anus.

A selective adaptation?

Many believe that there is an evolutionary justification for this behaviour, in that it facilitates optimal mate choice. Essentially the logic is that a male capable of satisfying a female by providing pleasure must have a great deal of ‘good’ genes – by providing such pleasure he is advertising this to the mate-selecting female, who will be looking for such traits to be inherited in turn by her sons, so that they too may also be good lovers and thus successful at further passing on her genes. This seemingly sound logic starts to fall apart when we consider the usual courtship process in most animals (including humans): it takes a lot of convincing by the male to encourage the female to copulate, so by the time intercourse is occurring she has in fact already decided that his genes are up to standards – the selection for genes has already occurred.

A non-selected by-product?

Symons’ ‘fantastic bonus’ hypothesis instead advocates that the female orgasm serves no evolutionary function at all, and is merely an evolutionary artefact resulting from shared embryonic development patterns in men and women: development in the first 8 weeks of life is parallel for both sexes and during this time nerve pathways are irreversibly laid down. In the same way that men acquire useless nipples due to parallel embryology, the female orgasm may well be a ‘fantastic bonus’. This is one of countless examples of natural selection as a force lacking foresight, hence artefacts like human male nipples and the ‘unintelligent design’ of the recurrent laryngeal nerve in giraffes. The idea that the clitoris is vestigial has also been proposed by other prominent scientists including Stephen Jay Gould.

There is compelling evidence against the ‘selective adaptation’ hypothesis through the sheer fact that sexual intercourse is not a reliable way for a female to achieve an orgasm: the percentage of women claiming to consistently orgasm without assistance (i.e. without clitoral stimulation in addition to vaginal penetration) is only 25%, comparatively lower than the 46% of women who consistently orgasm with clitoral stimulation in addition to penetration. Taking it further, the fact that such a high percentage of women fail to orgasm regularly (and some never at all) can be seen as evidence against any selective adaptation: while there is no doubt that male orgasm is an evolutionary necessity in producing a child, if the same were true of women we would expect female orgasm to be much more common.


From examining some of the studies in favour of ‘selective adaptation’ it seems that many are flawed in some way, and they have failed to produce compelling evidence to suggest a selection pressure. On the contrary the ‘fantastic bonus’ idea seems more convincing, discrediting flawed studies and providing its own reasonable justifications through familiar examples like the presence of male nipples. However a study could emerge that succeeds in identifying a correlation between female orgasm and evolutionary fitness: the possibility may not have been proven but is certainly not out ruled.

Perhaps the reason why the ‘fantastic bonus’ has not been so well received is because of its implications in fields outside of the scientific realm. It is easy to see why feminists, for example, would be concerned at a lack of evolutionary importance for the female orgasm, in the same way that some are concerned about sharing a common ancestor with chimpanzees and other animals. Regardless of possible misinterpretations, science should still concern itself with producing theories through evidence, and not leave relevant and interesting issues such as female orgasm undiscussed because of some possible political backlash.

By Chris Richardson.

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