In this SF Chronicle piece, Ash Zemenick discusses evidence for biological sex as a continuum rather than a binary. They argue that humans whose chromosomes, gametes, or hormones do not fit into a binary are common and that it is more useful to view them as a form of diversity rather than as an exception to a rule.
Remember Thomas the blind bisexual goose
ID: Thomas, a white goose, with two black swans named Henry and Henrietta. The three adults stand surrounding several gray baby swans sitting in a nest. Thomas played the role of a "doting uncle" to Henry and Henrietta's many children.
Thomas was a New Zealand goose who rose to prominence for his notable relationships and behaviors. He formed close, lasting bonds with both male and female swans and was involved in a "love triangle". Thomas became blind later in life. He reared many children, both his biological children and young orphaned geese and swans.
Below are two article commemorating Thomas’ life, published shortly after his death.
Queer Animals Are Everywhere. Science Is Finally Catching On.
This article by animal studies graduate student Eliot Schrefer for The Washington Post highlights a recent surge in scholarship on same-sex animal behavior which challenges longstanding misconceptions about the connection between animal sexuality and evolution.
Language Drops Visual Dictionary
This visual dictionary by Language Drops is available as a web page or a smartphone app. This can be a useful tool for working with multilingual students. For example, the link below is for a set of words called Words for Gender Pronouns in Arabic.
Dads Also Pass on Mitochondrial DNA, Contrary to Long-Standing Belief
This article from Smithsonian Magazine describes new evidence that some people receive their mitochondrial DNA from the sperm cell rather than the egg cell that made them. This contradicts a longstanding generalization that only egg cells contribute mitochondrial DNA.
This article uses the words mother/maternal and father/paternal to refer to two contributors of genetic material in humans. Consider speaking with your students about other terms that may be more inclusive of all people and their families, such as sperm-derived and egg-derived DNA.
The Intersex Roadshow (Blog)
In this blog, intersex sociologist Dr. Cary Gabriel Costello writes about current intersex issues in historical context.
Intersex people are supposed to lie low and keep quiet. Not me.
I'm not defective, I'm not disordered, I'm not ashamed. I just don't fit in your M/F boxes.
I'm intersex by birth and honest by choice.
Inclusive Zines from the Queer Sex Ed Community Curriculum
Clownfish, a dolphin, a whale, and other fish swim over the title “Sex Diversity in Nature: A brief exploration of sex diversity in the natural world.”
The Queer Sex Ed Community Curriculum is an LGBTQ-led project that is developing inclusive, trauma-informed, and sex-positive resources for use with youth. Their resource library includes zines, posters, and training materials that you can implement in your classroom. Check out the awesome Sex Diversity in Nature Zine, as well as their zine on Deconstructing the Gender Binary.
Transgender Researchers Want to Make an Impact
A female, transgender, and male symbol are written in chalk in the colors of the trans pride flag: pink, white, and blue. Equal signs are drawn between each symbol.
This article from Science News for Students is one way to introduce transgender identity in the science classroom. The article includes explanations of transgender identity and profiles several transgender researchers and how their identity intersects with their work as scientists.
The article is written in student-friendly language, and includes a glossary of “power words” that can be used as an additional learning tool.
Nature is Queer! Infographic
Check out this awesome infographic focused on diversity in the natural world created by Theo Bamberger, a graduate student working towards their Master’s of Education at the University of Washington. It highlights parallels between diverse expressions of gender and sexuality in nature with the diversity in human experiences.
Sex Redefined: The Idea of 2 Sexes Is Overly Simplistic
In this Scientific American article, Claire Ainsworth, discusses evidence for the spectrum model of biological sex using introductory language.
You don't have a male or female brain – the more brains scientists study, the weaker the evidence for sex differences
Lise Eliot of the Rosalind Franklin University of Medicine and Science addresses common misconceptions about differences between male and female brains. She reviewed 30 years of research on human brain sex differences and found that almost none of these claims are reliable. This article addresses claims of difference in brain size and composition in both humans and animals. Eliot discusses what this data means for nonbinary and transgender people.
The Unbelievable Secrets of Sex-Changing Animals
In Interesting Engineering, Trevor English surveys the common phenomenon of animals changing sex, and its physiological and genetic basis. For student-facing use, we recommend prefacing this article with a language distinction: Animals “change sex” meaning there is a change in their production of sex hormones and a physical change in their reproductive organs. Humans instead undergo “gender transition”, with “sex change” being an outdated term for this process.
Sex isn’t binary, and we should stop acting like it is
This article by Liza Brusman is available in English and Spanish, text or read loud.
Gynandromorph Animals - BBC Earth article
This BBC Earth article explores the rare phenomenon of bilateral gynandromorphs, or animals which develop different physical sex characteristics on their left and right side. This occurs when a cycle of meiosis yields multiple viable eggs rather than one egg and three polar bodies to be discarded. When two eggs are fertilized by sperm, mosaicism can occur in the sex chromosomes.
When introducing students to the article, the teacher should be sure to note that overgeneralizing language is briefly used to describe humans (“In humans, men have an X and a Y chromosome, while women have two X chromosomes.”) However, the article can still have value in demonstrating the nonbinary nature of biological sex and the scientific processes by which evidence is gathered to support this.
A Reddit post shows a gynandromorph lobster found in the wild:
Gender and Sex – Transgender and Intersex (Book Chapter)
This UMass Amherst textbook chapter models the use of precise, modern, and non-pathologizing language for discussing transgender and intersex topics in the context on human biology. The textbook authors are Miliann Kang, Donovan Lessard, Laura Heston, and Sonny Nordmarken. The chapter is available through Openbooks under a Creative Commons Attribution license.
Sex Determination – Why So Many Ways of Doing It?
Image shows simplified diagrams of some systems of sex determination - hermaphroditism in plants and fish, environmental sex determination in reptiles and plants, and genotypic sex determination in humans and birds.
This PLOS Biology article details the diverse mechanisms by which sex is determined in different species, how they evolved, and how they may look in the future. The article opens with a treatment of three common myths of sex determination.
Editor’s note: The term "hermaphrodite" is appropriate for referring to non-human animals with sex characteristics that do not fit typical binary notions of male or female bodies. For humans, “intersex” is the appropriate term—learn more here!
Although the entire reading is not for k-12 audiences, the three myths, Figure 3, Figure 4, and Box 2 are suitable for high school.
Journal: The Biological Contributions to Gender Identity and Gender Diversity: Bringing Data to the Table
This study is a review of evidence that gender identity is influenced by innate factors including genetics. The authors hypothesize that gender identity is a multifactorial complex trait with a heritable polygenic component, and that the study of this trait is important.
Although gender identity as a polygenic trait is only a hypothesis, this example could serve to show biology students how heritability studies can be used to gain a better understanding of a complex, socially relevant trait. Most textbooks cite skin color and height as examples of polygenic traits, and gender identity might be another to add to that list.
A Brief History of Twin Studies
Images shows twin brother astronauts Scott Kelly and Mark Kelly in front of a sliding glass door.
This article from Smithsonian Magazine summarizes how twin studies have been used untangle the influences of genes and the environment on particular traits. Twins have been used in the study of eugenics, I.Q., eating disorders, obesity, sexual orientation, and the effect of spaceflight on the body.
Resource: WHO Gender and Genetics
The World Health Organization website has a concise but comprehensive overview of the relationship between genetics, sex, and gender. This website presents an overview of the major ethical, legal, and social implications associated with gender and genetics. This website is a useful resource for students researching sex and gender in the context of genetics or health.