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Male, female, transgender, and other circular symbols made of multi-colored bones
Read this article, which details the reckoning archaeology has had to do when addressing the complex, non-binary nature of biological sex characteristics. Includes several case studies of ambiguous archaeological remains which have pushed scientists to reconsider preconceived notions of both gender and sex in prehistoric times.
In JSTOR Daily, Juliet Lamb discusses non-human species that gain advantages by project an opposite-sex appearance which has parallels to transgender humans.
This SciShow video reviews data concerning differences in the brains of biological males and biological females. The writers are careful to mention that research on this topic does not account for transgender or intersex individuals, and that neuroscience research as a whole is heavily focused on studying the brains of male humans and animals. You may also wish to discuss with students about the definition of “biological sex” and how that definition has changed throughout history.
The most accurate single indicator was sacrum shape (94.1%). On the other hand, three combinations of pelvic criteria produced higher levels of accuracy than the trait list as a whole: obturator foramen shape and presence of the ventral arc (98%); obturator foramen shape and presence of the ventral arc (98%); obturator foramen shape and true pelvis shape (98%); pubic shape and acetabulum shape and size (95%).
The William Bass Field Manual mentions other studies of European populations, but reproduces in full several tables by Rogers and Saunders based on 49 “adult skeletons from a 19th-century cemetery located on the grounds of the St Thomas Anglican Church in Belleville, Canada.”
Embedded below are tables for:
Table 3-24. Accuracy Levels for Each Individual Pelvic Trait (after Rogers & Saunders (1994:1051, Table 5) (Bass 2005: 216)
Table 3-25. Probability of Estimating Sex Correctly for Combinations of Two Traits (after Rogers & Saunders (1994:1051, Table 3) (Bass 2005: 216)
Curious about what the broad labels for male and female anatomical regions are for those anthropologists using the Bass Manual?
Source
Bass, William. 2005. Human Osteology: A Laboratory and Field Manual, 5th ed. Special Publication No. 2 of the Missouri Archaeological Society. Columbia, MO. http://coas.missouri.edu/mas
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.
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.
Image shows four intersex individuals smiling in front of a blue background.
In this video, four intersex individuals talk about the meaning of intersex, their personal identities, the difference between gender identity and biological characteristics, and "normalizing" surgery. In the biology classroom, this video is a way to supplement textbooks and other curricular resources that may pathologize and anonymize the topic of intersex traits.
Source: American Psychological Association. (2015). Guidelines for Psychological Practice with Transgender and Gender Nonconforming People. American Psychologist, 70 (9), 832-864. doi: 10.1037/a0039906
Research has primarily shown positive treatment outcomes when TGNC adults and adolescents receive TGNC-affirmative medical and psychological services (i.e., psychotherapy, hormones, surgery; Byne et al., 2012; R. Carroll, 1999; Cohen-Kettenis, Delemarre-van de Waal, & Gooren, 2008; Davis & Meier, 2014; De Cuypere et al., 2006; Gooren, Giltay, & Bunck, 2008; Kuhn et al., 2009), although sample sizes are frequently small with no population-based studies. In a meta-analysis of the hormone therapy treatment literature with TGNC adults and adolescents, researchers reported that 80% of participants receiving trans-affirmative care experienced an improved quality of life, decreased gender dysphoria, and a reduction in negative psychological symptoms (Murad et al., 2010).
In addition, TGNC people who receive social support about their gender identity and gender expression have improved outcomes and quality of life (Brill & Pepper, 2008; Pinto, Melendez, & Spector, 2008).
Several studies indicate that family acceptance of TGNC adolescents and adults is associated with decreased rates of negative outcomes, such as depression, suicide, and HIV risk behaviors and infection (Bockting et al., 2013; Dhejne et al., 2011; Grant et al., 2011; Liu & Mustanski, 2012; Ryan, 2009).
Family support is also a strong protective factor for TGNC adults and adolescents (Bockting et al., 2013; Moody & Smith, 2013; Ryan et al., 2010).
TGNC people, however, frequently experience blatant or subtle antitrans prejudice, discrimination, and even violence within their families (Bradford et al., 2007). Such family rejection is associated with higher rates of HIV infection, suicide, incarceration, and homelessness for TGNC adults and adolescents (Grant et al., 2011; Liu & Mustanski, 2012). Family rejection and lower levels of social support are significantly correlated with depression (Clements-Nolle et al., 2006; Ryan, 2009).
Many TGNC people seek support through peer relationships, chosen families, and communities in which they may be more likely to experience acceptance (Gonzalez & McNulty, 2010; Nuttbrock et al., 2009).
Peer support from other TGNC people has been found to be a moderator between antitrans discrimination and mental health, with higher levels of peer support associated with better mental health (Bockting et al., 2013).
Bockting, W. O., Miner, M. H., Swinburne Romine, R. E., Hamilton, A., & Coleman, E. (2013). Stigma, mental health, and resilience in an online sample of the US transgender population. American Journal of Public Health, 103, 943–951. http://dx.doi.org/10.2105/AJPH.2013 .301241
Brill, S., & Pepper, R. (2008). The transgender child: A handbook for families and professionals. San Francisco, CA: Cleis Press.
Byne, W., Bradley, S. J., Coleman, E., Eyler, A. E., Green, R., Menvielle, E. J., . . . American Psychiatric Association Task Force on Treatment of Gender Identity Disorder. (2012). Report of the American Psychiatric Association Task Force on Treatment of Gender Identity Disorder. Archives of Sexual Behavior, 41, 759 –796. http://dx.doi.org/10.1007/ s10508-012-9975-x
Carroll, R. (1999). Outcomes of treatment for gender dysphoria. Journal of Sex Education & Therapy, 24, 128 –136.
Clements-Nolle, K., Marx, R., & Katz, M. (2006). Attempted suicide among transgender persons: The influence of gender-based discrimination and victimization. Journal of Homosexuality, 51, 53– 69. http://dx .doi.org/10.1300/J082v51n03_04
Cohen-Kettenis, P. T., Delemarre-van de Waal, H. A., & Gooren, L. J. G. (2008). The treatment of adolescent transsexuals: Changing insights. Journal of Sexual Medicine, 5, 1892–1897. http://dx.doi.org/10.1111/j .1743-6109.2008.00870.x
Davis, S. A., & Meier, S. C. (2014). Effects of testosterone treatment and chest reconstruction surgery on mental health and sexuality in femaleto-male transgender people. International Journal of Sexual Health, 26, 113–128. http://dx.doi.org/10.1080/19317611.2013.833152
De Cuypere, G., Elaut, E., Heylens, G., Van Maele, G., Selvaggi, G., T’Sjoen, G.,... Monstrey, S. (2006). Long-term follow-up: Psychosocial outcomes of Belgian transsexuals after sex reassignment surgery. Sexologies, 15, 126 –133. http://dx.doi.org/10.1016/j.sexol.2006.04.002
Dhejne, C., Lichtenstein, P., Boman, M., Johansson, A. L. V., Långström, N., & Landén, M. (2011). Long-term follow-up of transsexual persons undergoing sex reassignment surgery: Cohort study in Sweden. PLoS ONE, 6(2), e16885. http://dx.doi.org/10.1371/journal.pone.0016885
Gooren, L. J., Giltay, E. J., Bunck, M. C. (2008). Long-term treatment of transsexuals with cross-sex hormones: Extensive personal experience. Journal of Clinical Endocrinology & Metabolism: Clinical and Experimental, 93, 19 –25. http://dx.doi.org/10.1210/jc.2007-1809
Grant, J. M., Mottet, L. A., Tanis, J., Harrison, J., Herman, J. L., & Kiesling, M. (2011). Injustice at every turn: A report of the national transgender discrimination survey. Washington, DC: National Center for Transgender Equality & National Gay and Lesbian Task Force. Retrieved from http://endtransdiscrimination.org/PDFs/NTDS_Report .pdf
Kuhn, A., Brodmer, C., Stadlmayer, W., Kuhn, P., Mueller, M. D., & Birkhauser, M. (2009). Quality of life 15 years after sex reassignment surgery for transsexualism. Fertility and Sterility, 92, 1685–1689. http:// dx.doi.org/10.1016/j.fertnstert.2008.08.126
Liu, R. T., & Mustanski, B. (2012). Suicidal ideation and self-harm in lesbian, gay, bisexual, and transgender youth. American Journal of Preventive Medicine, 42, 221–228. http://dx.doi.org/10.1016/j.amepre .2011.10.023
Moody, C. L., & Smith, N. G. (2013). Suicide protective factors among trans adults. Archives of Sexual Behavior, 42, 739 –752. http://dx.doi .org/10.1007/s10508-013-0099-8
Murad, M. H., Elamin, M. B., Garcia, M. Z., Mullan, R. J., Murad, A., Erwin, P. J., & Montori, V. M. (2010). Hormonal therapy and sex reassignment: A systemic review and meta-analysis of quality of life and psychosocial outcomes.Clinical Endocrinology, 72, 214 –231. http:// dx.doi.org/10.1111/j.1365-2265.2009.03625.x
Pinto, R. M., Melendez, R. M., & Spector, A. Y. (2008). Male-to-female transgender individuals building social support and capital from within a gender-focused network. Journal of Gay and Lesbian Social Services, 20, 203–220. http://dx.doi.org/10.1080/10538720802235179
Ryan, C. (2009). Supportive families, healthy children: Helping families with lesbian, gay, bisexual & transgender children. San Francisco, CA: Family Acceptance Project, Marian Wright Edelman Institute, SanFrancisco State University. Retrieved from http://familyproject.sfsu.edu/files/FAP_English%20Booklet_pst.pdf
Ryan, C., Russell, S. T., Huebner, D., Diaz, R., & Sanchez, J. (2010). Family acceptance in adolescence and the health of LGBT young adults. Journal of Child and Adolescence and the Health of LGBT Young Adults, 23, 205–213.
Source: http://www.lgbthealtheducation.org/wp-content/uploads/LGBT-Health-Care-for-Asian-Americans.pdf
References:
Mosher WD, et al. (2005) Sexual behavior and selected health measures: men and women 15-44 years of age, United States, 2002. Advance Data; 2005:362.
Pathela P, et al. (2006) Discordance between sexual behavior and self-reported sexual identity: a population-based survey of New York City men. Ann Intern Med. 2006;145(6):416-425.
Description: A screenshot taken of a biology teacher’s post on Facebook.
A few of the facts that biology teacher Grace Pokela shares:
sex chromosomal variety: Insects use an XO sex determination system, while birds use the ZW system.
environmental factors for sex: A reptile’s sex is at least partly determined by the temperature in which the egg develops.
hermaphroditism: Flatworms transfer sperm through a process called penis fencing (which is described in graphic detail here).
hermaphroditism & sex change: In clownfish colonies, dominance is based on size, the female being the largest and the male being the second largest. If the female dies, the male gains weight and becomes the female for that group.
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!
transgender behavior: Other fish species take on female attributes while mating, and they release sperm in the process.
2+ sexes: Fungi like molds and mushrooms have 36,000 sexes.
In humans, 5-alpha-reductase deficiency is a real (albeit rare) condition, in which young women grow a penis during puberty.
In humans, androgen insensitivity syndrome (AHS) is an intersex condition in which a person who is genetically male is resistant to male hormones . As a result, the person has some or all of the physical traits of a woman, but the genetic makeup of a man.
In humans, the SRY gene is involved in male sexual development—without it fetuses can be genetically male (with XY chromosomes) but have a female body. The same is true in females (with XX chromosomes), who can develop a male body without the SRY gene.
In humans, XXY males are sterile, with small testes—while women with only one X chromosome (a condition called Turner syndrome) are infertile and don’t go through puberty. Males with two X chromosomes (called Klinefelter syndrome) are taller, with a higher risk of breast cancer and osteoporosis.
Read more at https://observer.com/2017/03/transgender-facebook-troll-biology-sexuality/
This SciShow video reviews several intersex traits in humans and several patterns of hermaphroditism in animal species. At different times in the video, the host describes this phenomenon as a “condition,” “disorder,” and “variation”. You may wish to discuss the impact of these word choices with your students.
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!
This SciShow video summarizes the complexity of human sex determination, which often wrongly thought to be binary. Mosaicism, chimerism, and intersex traits and nonconsensual surgeries are mentioned.
This video from Facts in Motion illustrates how the sex of crocodiles is determined by environment and not genetics. The sex ratio of developing crocodile eggs is shown to be a function of temperature, thought to be mediated by a thermosensor protein. Climate change may impact or even cause the extinction of crocodile populations.
This sex-determination system is not so “unusual” because it occurs in other reptiles and fish species. But it is certainly interesting and gathering attention. The College Board’s 2018 AP Biology exam had a free response question about temperature-dependent sex determination in fish.
In this article in The Scientist, Shawna Williams reviews current research on how brain structures may be linked to gender identity.
Check out the 🔎SPECIES DATABASE from Stanford biologist Joan Roughgarden’s book, EVOLUTION’S RAINBOW (University of California Press). Click the link above, or check out the embedded document below for 200+ species from the asexual, gay, lesbian, transgender, intersex, and hermaphrodite spectra. Includes behavior, neurobiology, and chromosomal phenomena.
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!