Sex can be classified in many ways depending on the species and context. The one fundamental method of classification that applies to all living things is to look at the size of the gametes. This article summarizes the concept of anisogamy (having two gametes of different size) and its evolutionary origins.
Archaeology's Sexual Revolution
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.
Other, Neither, Both - Talk by Sam Sharpe
Biological sex takes on so many diverse patterns across species, but discussion of human sex often consists of an oversimplified and incomplete binary. Biologist Sam Sharpe discussed this issue in a five-minute INSPIRE talk at the Ecological Society of America annual meeting in 2020.
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.
Article: Transgender People and “Biological Sex” Myths
In this Medium article, biochemist and writer Julia Serano discusses the myth of a binary biological sex, and its implications for oppression and social justice.
Glossary resources, sports access, and new podcast appearances [Apr]
Hi, everyone!
You are in our thoughts during this challenging time. Though we are physically isolated from our students and each other, the Gender-Inclusive Biology team would like to share gender-inclusive resources for remote learning and support.
Please email us if you have other suggestions or are seeking help.
Check the end for an invitation to the first of a series of informal social hours on Zoom.
Useful gender-inclusive resources for teaching remotely: Here are a few assets that we think will be useful for teachers distributing lessons remotely during this time. Please email us if you have other suggestions to add to this list!
Activity: Sex verification in athletes This activity guides students through analyzing data and the history of how sex verification in athletes has changed over time. When using with students, you can emphasize the idea that "biological sex" is an ambiguous, non-scientific term with a definition that has changed over time.
Video: There are more than two human sexes This engaging video (mostly geared towards the high school level) is a great introduction to diversity of sex characteristics and distinguishes the differences between sex and gender identity.
Video: Secrets of the X Chromosome This video and lesson addresses the differences between sex chromosomes and autosomes, including high-engagement topics like colorblindness, identical twins, and cats, all while approaching sex and gender using more accurate language than most online resources.
Gender-inclusive Biology Talkspace/Social hour: We will be hosting our first informal check-in space for educators interested in Gender-Inclusive Biology on Thursday, April 16th at 3 PM Pacific/6 PM Eastern via Zoom. If you are interested in joining us, please email Lewis (fishyteaching@gmail.com) for the link to join in!
Upcoming appearances:
Many in-person conferences have been canceled in the coming months. However, there are some exciting opportunities to connect with Gender-Inclusive Biology Education and related work in online and remote settings.
Sam gave a 30-minute webinar about Gender-Inclusive Biology on the STEM Village on Monday, April 6th - you can check out the video recording here!
Jamie Kubiak, a chemistry teacher in New York City, gave a recent webinar on creating LGBTQ-inclusive classrooms. You can view the recording and see the slide deck here.
Sam has been doing a Twitter series focused on dispelling common stereotypes and misconceptions about Asian-Americans by sharing his own stories and the stories of Asian-American heroes in STEM and beyond. You can check the project out using the hashtag #ExpectAsianVsReality
Sincerely,
Lewis, Sam, and River
The Gender-Inclusive Biology Team
All female spotted hyenas have penises they use to mount, pee, & give birth. (Gender Showcase, 9-12)
Editor’s note: Earlier, the author defines “penis” in this discussion as something the animal can pee through. —RXS
All female spotted hyenas have functional penises. They use it pee, signal, anally mount males & females for dominance, and give birth.
Intersex plumbing is found in ALL females of the spotted hyena (Crocuta crocuta) of Tanzania—in which the females have penises nearly indistinguishable from those of the males. (EN23)…The first scientific investigation in 1939 showed that a spotted hyena makes only one-size gamete throughout its life, either as an egg or sperm. (EN24) Thus these hyenas are not hermaphrodites. Rather, female spotted hyenas are intersexed, like some female bears.
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!(EN23) L. Frank, 1996, Female masculinization in the spotted hyena: Endocrinology, behavioral ecology, and evolution, pp. 78-131 in J. Gittleman, ed., Carnivore Behavior and Evolution, vol. 2, Cornell University Press; L. Frank, 1997, Evolution of genital masculinization: Why do female hyenas have such a large ‘penis’? Trends Ecol. Evol. 12:58-62.
(EN24) M. Harrison, 1939, Reproduction in the spotted hyena, Crocuta crocuta (Erxleben.), Phil. Trans. Roy. Soc. Lond., ser. B, 230-1-78.
The females have a phallus 90% as long and the same diameter as a male penis (yes, somebody measured, 171 millimeters long and 22 millimeters in diameter). The labia are fused to form a scrotum containing fat and connective tissue resembling testicles. The urogenital canal runs the length of the clitoris, rather than venting from below. The animal can pee with the organ, making it a penis. Completing the picture, the female penis contains erectile tissue (corpus spongiosum) that allows erections like those of a male penis.
Sex & reproduction with two penises is as costly as pre-Industrial human reproduction, so why has this survived so long? (book excerpt)
A female spotted hyena mates and gives birth through her penile canal. When mating, a female retracts the penis on itself, ‘much like pushing up a shirtsleeve,’ and creates an opening into which the male inserts his own penis. The female’s penis is located in the same spot as the male’s penis, higher on the belly than the vagina in most mammals.
Therefore, the male must slide his rear under the female when mating so that his penis lines up with hers. During birth, the embryo traverses a long and narrow birth canal with a sharp bend in it. About 15% of the females die during their first birth, and they lose over 60% of their firstborn young. (EN 25) These obvious disadvantages lead us to question why female spotted hyenas have this penis instead of a clitoris.
(EN25) L. Frank and S. Glickman, 1994, Giving birth through a penile clitoris: Parturition and dystocia in the spotted hyena (Crocuta crocuta), J. Zoology London 206:525-31; L. Frank, M. Weldele, and S. Glickman, 1995, Masculinization costs in hyenas, Nature 377:584-85.
Erect hyena penises are a sign of submission; the female hyena without the erect penis is the dominant leader of the entire pack. (book excerpt)
Female spotted hyenas have a dominance hierarchy, and the erect penis is a signal of submission. When two females interact with each other in a struggle for dominance, the one who wants to back down signals by erecting her penis. (EN26) No one knows why female hyenas evolved this method of signaling.
(EN26) M. East, H. Hofer, and W. Wickler, 1993, The erect “penis” is a flag of submission in a female-dominated society: Greetings in Serengeti spotted hyenas, Behav. Ecol. Sociobiol. 33:355-70; H. Hofer and M. East, 1995, Virilized sexual genitalia as adaptations of female spotted hyenas, Revue Suisse de Zoologie 102:895-906.
Erections occur in the “meeting ceremony” when animals greet after having been apart. The animals approach each other and stand alongside one another, head-to-tail, one or both lifting her hind leg to allow inspection of her erect penis. When only one member of a greeting pair displays an erection, she is normally the subordinate.
Each hyena puts her reproductive organs next to powerful jaws. Greetings between captive females that have been separated for a week are tense and frequently wind up in a fight that starts when one bites the genitals of the other, doing occasional damage to the reproductive capability of the injured party.
[This] social-inclusionary trait…allows a female hyena access to resources needed for reproduction and survival. If a female were not to participate in social interactions using her penis for signaling, she would not be able to function in hyena society and presumably would either die or fail to breed.
[Testosterone from elevated aggression in hyena society can’t develop] a full-fledged replica of male genital anatomy, complete with scrotal sacs and fat bodies resembling testicles. This structure can’t develop from a few extra splashes of testosterone in the blood.
Citation: Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. pp. 138-39.
Article: "Stop Using Phony Science to Justify Transphobia"
In this Scientific American article, Simón(e) D Sun explains how misunderstandings of science have been used to dehumanize trans people in society. Sun explains how genetic sex and the relationship between the body, brain, and hormones are both complex and validate the existence of transgender people.