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Can evolutionary thinking shed light on gender diversity?

  • Bernadette Wren (a1), John Launer (a2), Michael J. Reiss (a3), Annie Swanepoel (a4) and Graham Music (a5)...


Issues of sexual reproduction lie at the core of evolutionary thinking, which often places an emphasis on how individuals attempt to maximise the number of successful offspring that they can produce. At first sight, it may therefore appear that individuals who opt for gender-affirming medical interventions are acting in ways that are evolutionarily disadvantageous. However, there are persuasive hypotheses that might make sense of such choices in evolutionary terms and we explore these here. It is premature to claim knowledge of the extent to which evolutionary arguments can usefully be applied to issues of gender identity, although worth reflecting on the extent to which nature tends towards diversity in matters of sex and gender. The importance of acknowledging and respecting different views in this domain, as well as recognising both the uncertainty and likely multiplicity of causal pathways, has implications for clinicians. We make some suggestions about how clinicians might best respond when faced with requests from patients in this area.


After reading this article you will be able to:

  • understand evolutionary arguments about diversity in human gender identity
  • identify strengths and weaknesses in evolutionary arguments applied to transgender issues
  • appreciate the range and diversity of gender experience and gender expression among people who present to specialist gender services, as well as the likely complexities of their reasons for requesting medical intervention.


Corresponding author

Correspondence Dr Bernadette Wren, Tavistock and Portman NHS Trust, 120 Belsize Lane, London NW3 5B, UK. Email:


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DECLARATION OF INTEREST: The authors are members of the evo-psychotherapy study group at the Tavistock Clinic, London. The aim of the group is to promote evolutionary thinking in psychotherapy and psychiatry.



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Can evolutionary thinking shed light on gender diversity?

  • Bernadette Wren (a1), John Launer (a2), Michael J. Reiss (a3), Annie Swanepoel (a4) and Graham Music (a5)...


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Can evolutionary thinking shed light on gender diversity?

  • Bernadette Wren (a1), John Launer (a2), Michael J. Reiss (a3), Annie Swanepoel (a4) and Graham Music (a5)...
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Gender is not a protected characteristic

David Curtis, Honorary Professor, UCL
03 February 2020

This statement is incorrect: "In the UK, it is important for clinicians to know that UK equality legislation (the Equality Act 2010) makes discrimination based on gender illegal." In the Equality Act, sex is a protected characteristic. Sexual orientation is also protected. Gender is not. Gender reassignment is a protected characteristic, meaning that one cannot for example discriminate against somebody who needs to take time off work to attend hospital appointments or surgery. Discrimination based on gender is not illegal. The protected characteristics are listed online and easily verified:

It is untrue that gender-diverse people are legally entitled to choose their pronouns, their school uniform or their changing rooms, as stated in the article. Accommodation may be made for them if it does not impact the rights of others. Allowing males into female changing rooms could discourage females from using those facilities and so could constitute indirect discrimination under the Equality Act.

Finally, the authors repeatedly refer to "sex assigned at birth". Sex is not assigned at birth. It is observed. I would expect doctors to know this.

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Conflict of interest: None declared

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