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Sex ≠ Gender

A guest post from Talia Young, Ph.D., David H. Smith Conservation Postdoctoral Fellow, Princeton University & Director of Fishadelphia

I recently saw another ecology talk refer to “gender ratios” of fish. I’d like to talk about the difference between sex and gender, and why ecologists should care about this topic.  


The words “sex” and “gender” are often used interchangeably in colloquial contexts, but they have different meanings that are relevant to our work in ecology.

Sex” refers to categories based on a combination of biological and physical characteristics, such as body organs, chromosomes, and hormones (WHO 2011, APA 2015). Sex is commonly assigned on the basis of external genitalia at birth and is often assumed to be only male or female, but scientists have identified at least five different groupings of human sex chromosomes, anatomy, and hormone physiology (Fausto-Sterling 1993).  Other terms that relate to sex include intersex, freemartin, and hermaphrodite. (Note that hermaphrodite is a term currently used for animals but considered outdated and rude when used to describe humans; the preferred contemporary term for humans is intersex.)  (“Sex” can also refer to activity among one or more individuals that may or may not result in sexual arousal and/or genetic recombination. I’m not addressing this meaning of the word in this piece.)

Gender” refers to identities and categories based on social or cultural characteristics (WHO 2011, APA 2015). Gender is both internal (gender identity, which is each person’s innate sense of their own gender), and external (gender expression, which is how each person expresses their gender identity). Woman, man, masculine, and feminine are all terms that can refer to gender. Transgender is a term used to describe a person whose gender identity is different from the sex they were assigned at birth. Gender is primarily a human and social term, and it is not usually relevant for non-human animals or plants.

When we observe biological and physical aspects of our study organisms, those observations tell us about the sex of those individuals, not the gender.

When we interact with other humans, we usually know more about their gender rather than their sex: for example, we often know about their clothing and hairstyles but not very much about their body organs, chromosomes, or hormones.  (Furthermore, and this fact may be obvious, but clothing and hairstyles are not necessarily signifiers of any particular gender identity.)  Among humans, sex and gender may be related, but they are not equivalent. In other words, female and woman are often thought to be synonymous, but in reality, female refers to different characteristics than woman does.

It also seems worth noting that both of these sets of categories (sex and gender) are imperfect systems that we have developed in an attempt to describe the world we live in.  As with all categorization systems (such as species, or developmental stages), the world is more complicated than our words can capture.


  1. If (a) you work with plants or animals, and (b) you are interested in categories such as female and male, and (c) those categories are determined by biological or physical criteria (such as presence of sexual organs or gonads, sexually dimorphic coloring, or hormone levels), the accurate term to use is “sex,” not “gender.” See examples in Table 1.

  1. If you (a) are talking about scientists and (b) interested in categories such as “women” and “men,” it’s more polite to use gender rather than sex categories. Why? In professional contexts, we may think we know what gender our colleagues present themselves as (e.g., women, men), but probably don’t know very much about the biological sex of our colleagues (e.g., chromosomes, body organs, hormones). It’s odd and inappropriate to make assumptions about other people’s bodies, especially in a professional context. See examples in Table 2. It’s also worth noting that it’s polite to ask people how they prefer to be described. For example, you might ask, “What are the best pronouns to use for you?”

Why is this language important?

  1. Accuracy. As ecologists, we are a profession dedicated to describing our beautiful but chaotic and messy world with the best accuracy we can muster. Using language correctly and appropriately is one important part of that work. If you have ever made a distinction between a substantial and significant difference, or taught a student that a single data point is singular while data are collectively plural, the difference between “sex” and “gender” is just one more way to increase the accuracy of our language and our work.
  2. Respect. Using gender rather than sex categories when talking about humans means that we do not make intrusive assumptions about other people’s bodies.


  • Language matters.  Using accurate language is important both in our work and in our community.  Being careful with our language helps us improve the quality of our science and allows us to describe our world with greater accuracy.  It also helps us build a considerate and thoughtful community of scientists.
  • Improving the accuracy of our language is a lifelong process.  None of us started out understanding the difference between a substantial and a significant change, or an individual’s sex and gender.  But one of the gifts of being scientists is that we are constantly learning new things about our world. Doing so helps us become both better scientists and better people.

Questions?  Comments? I’d love to hear them. Email me at #sexvsgenderinecology


Thanks to K. Baker, H. Batson, S. Borrelle, N. EtShalom, Y. EtShalom, S. Fox, S. Kassabian, E. Kaufman, and C. McDonough MacKenzie for suggestions and improvements to this piece.  All errors are mine.


Other resources

  • Krieger, N. 2003. Genders, sexes, and health: what are the connections—and why does it matter? International Journal of Epidemiology, 32(4), 652–7,
  • Fausto-Sterling A. 2000. Sexing the Body: Gender Politics and the Construction of Sexuality. New York, NY: Basic Books.

Banner image photo credits: Mimi Kessler and Don Young

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