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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.
Elizabeth Duthinh, a physician and high school teacher, developed these inclusive activity and practice problem sets covering the Monohybrid Cross, Dihybrid Cross, X-linked Traits, Non-Mendelian Inheritance, and the PTC taste lab.
Elizabeth writes:
These problem sets and PTC tasting lab are adapted to cover Mendelian genetics without presuming gender based on chromosomes and without assuming families and individuals are cisgender or heterosexual. We suggest pairing the X-linked characteristics problem set with the video What it's Like to be Intersex by InterACT and a short introduction to the SRY region of the Y chromosome.
This highly accessible lesson was designed by Sabrina Kayed for Grade 11 Biology. The lesson is designed to move students’ understanding of biological sex beyond the simplistic binary model and introduce them to the idea of sex as a spectrum.
Analysis of ancient DNA found in Finland has unveiled a surprise a century later – the remains of an early medieval warrior thought to be female may have been nonbinary. Xcaret Nuñez reports for NPR.
The data indicate that the person had a feminine presentation, likely XXY chromosomes, and a penis. The way they were buried led to the conclusion that the remains were of "a respected person whose gender identity may well have been non-binary."
To use this article with students, pre-teach the difference between gender and sex because this is not well-defined in the article.
A host of factors figure into whether someone’s biological sex appears female, male, or somewhere in between. This reference poster from Scientific American represents some elements in the spectra of gender (identity) and (biological) sex.
Though this poster uses the phrase "intersex conditions", we advise using "intersex traits" instead.
Creator Amanda Montañez tells the story behind the infographic in her article, "Visualizing Sex as a Spectrum".
Emily Quinn, an intersex activist, delivered this 14-minute talk at the TedWomen 2018 event. Emily tells her personal story and discusses the little-known truth that biological sex is a spectrum and not a binary. This is true whether we measure biological sex by chromosomes, hormones, gonads, or external genitalia. She dispels the myth of intersex people as extremely rare outliers, and humanizes diversity in biological sex.
It's rare to meet an intersex person that hasn't been operated on. Oftentimes, these surgeries are done to improve intersex kids' lives, but they usually end up doing the opposite, causing more harm and complications, both physical and emotional. I'm not saying that doctors are bad or evil. It's just that we live in a society that causes some doctors to "fix" those of us who don't fit their definition of normal. We're not problems that need to be fixed. We just live in a society that needs to be enlightened.
This video is uploaded to Youtube but its mature content tag makes it inaccessible through some school internet filters. Alternatively, TED.com page contains the video, transcript in 24 languages, and further reading list.
Pedigree charts are one of the most requested topics that we get from visitors to our website. We have built a guidance document below that will be continually updated. You can also view it on Google Docs.
Image https://www.theknowledgeroundtable.com/tutorials/decoding-pedigrees-made-easy/ What is a pedigree chart? A pedigree chart is a diagram that shows the occurrence of phenotypes through several generations of genetically related individuals. Because a pedigree chart is often confused with a family tree, and uses symbols to differentiate males and females, it is important for educators to give clear and inclusive messaging to their students about these charts.
GLSEN and interACT developed the Gender Triangle as an educational tool to highlight the main components that revolve around gender identity—our bodies, how we use our bodies to express ourselves, and how the world around us reads our bodies based on the cultural and social codes of our time and place.
This is the second episode of the PBS documentary series “9 Months That Made You.” The episode uses family interviews, documentary footage, and computer animations to detail the relationship between genetic and phenotypic variations in humans. Among those featured is güevodoces, a specific intersex trait observed in the Dominican Republic. We felt that the individuals were portrayed with empathy and autonomy, and using modern language. As a post-viewing exercise, students may discuss the various choices of language used to describe variation within the episode.
The güevodoces clip can be streamed for free on Vimeo. The entire episode can be streamed for free on Kanopy with a public library card or university login. It is also available with a paid subscription on Netflix and PBS as of the time writing this post.
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.
This brochure gives best practices for educators addressing the topic of intersex in classrooms, sex education classes, and school health centers. This resource was created by InterACT Youth and informed by their personal experiences.
Some schools do a lab exercise where students stain their own cells and determine their sex chromosomes (X and Y). This is a letter from the Executive Director of interACT that can be used to advocate for not doing this exercise due to the potential harm it can cause for intersex individuals.
Honeybee eggs start out male by default!
Most of the time, unfertilized bee eggs develop into males and fertilized bee eggs develop into females.
In their haplodiploidy sex determination system, males have 1/2 the chromosomes that females do, so the males are haploid and females are diploid.
Double-diploid bees are automatically cannibalized by the nurse bees.
The total number of chromosome sets determines whether bees become male, female, or a mix. This haplodiploidy system means all male bees are haploid and all females are diploid (see above). Male bees have half the number of chromosomes that female bees do.
Distinguish this from XO sex determination, where only the number of sex chromosomes are halved, not the autosomes. For example, males and females both receive the same number of autosomal chromosomes, but males only get O for their sex chromosome (1 chromosome) and females get XX for their sex chromosome set (2 chromosomes).
Fertilized eggs are either homozygous at the Sex Determination Locus (SDL) and differentiate into diploid males or are heterozygous and develop into females. The diploid males, however, don't survive in a bee colony as they are eaten by worker bees shortly after hatching from the egg. Fertile males are produced by the queen's unfertilized, haploid eggs that are hemizygous at SDL. (Gempe et al. 2009)
Image credit: Ian Alexander
Gempe et al. (2009) tested areas in the Apis mellifera sequence and manipulated the complementary sex determiner gene (csd in excerpt below) and the feminizer gene (fem in excerpt below). They tried different ways of suppressing and adding the influence of these genes. They discovered that female bee development requires fem activity and csd activity processes the heterozygous (female) state and not the homozygous or hemizygous (male) states.
We show that heterozygous csd is only required to induce the female pathway, while the feminizer (fem) gene maintains this decision throughout development. By RNAi induced knockdown we show that the fem gene is essential for entire female development and that the csd gene exclusively processes the heterozygous state. Fem activity is also required to maintain the female determined pathway throughout development, which we show by mosaic structures in fem-repressed intersexuals. We use expression of Fem protein in males to demonstrate that the female maintenance mechanism is controlled by a positive feedback splicing loop in which Fem proteins mediate their own synthesis by directing female fem mRNA splicing. The csd gene is only necessary to induce this positive feedback loop in early embryogenesis by directing splicing of fem mRNAs. Finally, fem also controls the splicing of Am-doublesex transcripts encoding conserved male- and female-specific transcription factors involved in sexual differentiation.
This means that fatal mutations automatically kill their haploid males, and double-diploid bees automatically get cannibalized by nurse bees when they hatch! But recently, researchers discovered an unusual intersex honeybee, shown below.
Figure 1 (a-k). Individual of Euglossa melanotricha with male and female phenotypic characteristics. a Side view (right), b side view (left), c front view of the head, d scutellum with a scutellar tuft (as observed in the female of this species), e view of the abdomen showing the sting, f ventral view of the sting, g dorsal view, h metatibia (left) with the presence of slit, i metatibia (right) with corbicula, j mesotibia (left) with velvety area and basal and distal cushions, k mesotibia (right side).
Researchers discovered an orchid bee that had a blend of male and female body parts and genetics, though genetic analysis allowed them to conclude this bee is mostly feminine.
Findings obtained through both morphological and genetic analyses of a gynander orchid bee (Euglossa melanotricha). For the genetic analysis, microsatellite markers were used to genotype the gynander bee. The morphological analysis revealed that the individual studied had a sting, and most parts of the insect body showed female phenotype, except for the three left legs. As in other reports on gynanders of orchid bees, the specimen of E. melanotricha analyzed herein was included in the category of mixed (or mosaic). From the seven microsatellite loci amplified, five were heterozygous for both male and female tissues, indicating that the organism analyzed is compatible with a diploid organism and not with a hemizygous or haploid one. Both the morphological and genetic characteristics of the gynander of E. melanotricha analyzed reveal that this specimen shows predominantly female characteristics.
Yet, Suzuki and colleagues suggest that this female-male labeling is not as clarifying as directly studying the mechanisms would be, and urge other researchers to look further into csd gene regulation:
In parallel, when considering the genetic uniformity of phenotypically different tissues (male and female) of this individual, the gynandromorph of E. melanotricha would be, in fact, an intersex bee.
In the current literature, there are over 100 reports of anomalous bees, showing both female and male phenotypes in the same individual, usually named gynander or gynadromorph (Wcislo et al. 2004; Michez et al. 2009). In light of the above scenario [of possible sampling bias discussed in omitted text], we suggest that future studies on gynander and intersex bees should give more emphasis to the understanding of the mechanisms involved in the csd gene regulation in an attempt to better elucidate how these anomalous organisms are generated.
Interested in haplodiploidy?
This sex determination system exists in all insects, Hymenoptera (bees, ants, wasps) and Thysanoptera (thrips), rotifers, Hemiptera (cicadas, aphids, leafhoppers), and Coeoptera (bark beetles).
Gempe, T., Hasselmann, M., Schiøtt, M., Hause, G., Otte, M., & Beye, M. 2009. Sex Determination in Honeybees: Two Separate Mechanisms Induce and Maintain the Female Pathway. PLoS Biol. 2009 Oct; 7(10): e1000222. doi: 10.1371/journal.pbio.1000222. PMID: 19841734.
Hoff, M. 2009. Male or Female? For Honeybees, a Single Gene Makes All the Difference. PLoS Biol. 2009 Oct; 7(10): e1000186. doi: 10.1371/journal.pbio.1000186. PMID: 20076733.
“The origin of the gynandromorphs has been attributed to genetic problems, and although different hypotheses have been raised to explain genetically the origin of the gynandromorphism in bees, the mechanisms that generate these abnormal individuals have not been elucidated.” Michez, D., Rasmont, P., Terzo, M., Vereecken, N.J. (2009) “A synthesis of gynandromorphy among wild bees (Hymenoptera: Apoidea), with an annotated description of several new cases.” Ann. Soc. Entomol. Fr. 45, 365–375
Michez, D., Rasmont, P., Terzo, M., Vereecken, N.J. (2009) A synthesis of gynandromorphy among wild bees (Hymenoptera: Apoidea), with an annotated description of several new cases. Ann. Soc. Entomol. Fr. 45, 365–375
Suzuki, K.M., Giangarelli, D.C., Ferreira, D.G. et al. (2015) “A scientific note on an anomalous diploid individual of Euglossa melanotricha (Apidae, Euglossini) with both female and male phenotypes”. Apidologie (2015) 46: 495. https://doi.org/10.1007/s13592-014-0339-5.
Wcislo, W.T., Gonzalez, V.H., Arneson, L. (2004) A review of deviant phenotypes in bees in relation to brood parasitism, and a gynandromorph of Megalopta genalis (Hymenoptera: Halictidae). J. Nat. Hist. 38, 1443–1457.
Narita, S., Pereira, R.A.S., Kjellberg, F., Kageyama, D. (2010) Gynandromorphs and intersexes: potential to understand the mechanism of sex determination in arthropods. Terr. Arthropod Rev. 3, 63–96.
How do changing temperatures affect a crocodile egg’s development?
How will average global temperature changes affect a crocodile egg’s development?
Predict an increase, decrease, or stable population change if average temperatures increase or decrease.
Book excerpt: Among reptiles, specifically turtles, crocodiles, and some lizards, gonadal identity is determined by the temperature at which eggs develop, not by chromosomes. The eggs are usually laid in the ground and covered with sand or moist dirt from which they absorb water, swelling in size as they age. Reptile embryos start developing within their egg, and after a while primordial germ cells form. When reptile primordial germ cells move to the genital ridges of their parents, both the germ cells and the parental embryo presumably experience the same environmental temperature. Both germ cells and parent therefore receive the same message about which sex to develop as, and their agendas automatically agree.
Scientists reported the first case of intersexuality in an African dwarf crocodile (Osteolaemus tetrapspis), a 10 year-old male-presenting crocodile with gonads that were ovotestes.
We used to think crocodiles couldn’t be intersex, because we had never found any before. Our understand was that crocodiles needed two separate types of cells that never occur together.
This discovery shows we have so many more questions to ask about sex determination!
Image caption: A dwarf crocodile. (C) Jim Frazee
Because the model we use to explain sex determination in crocodiles cannot help explain this evidence, we must keep asking questions and build better models for looking at our evidence.
Langer: Half of the 22 extant species of crocodilians have been examined for occurrence of temperature dependent sex determination (TSD). In TSD reptiles, masculinizing temperatures yield 100% or a majority of males, whereas feminizing temperatures yield 100% or a majority of females. In the transition range of temperature (TRT), a mix of males, females and sometimes intersexes are obtained. However, the molecular mechanisms behind TSD and an explanation for the occurrence of intersexuality remain elusive.
References
C. Johnston, M. Barnett, and P. Sharpe, 1995, The molecular biology of temperature-dependent sex determination, Phil. Trans. R. Soc. Lond., ser. B, 350: 297-304.
J.W. Lang and H. Andrews, 1994, Temperature-dependent sex determination in crocodilians, J. Exp. Zool. 270-28-44.
S. Langer, K. Ternes, D. Widmer, & Frank Mutschmann. The first case of intersexuality in an African dwarf crocodile (Osteolaemus tetraspis). Zoo Biol. 33:459–462, 2014. DOI:10.1002/zoo.21149
C. Smith and J. Joss, 1993, Gonadal sex differentiation in Alligator mississippiensis, a species with temperature-dependent sex determination, Cell Tissue Res. 273:149-62.
Wibbles, Bull, and Crews, 1994, Temperature-dependent sex determination. Journal of Experimental Zoology 270(1):71 - 78. DOI: 10.1002/jez.1402700108
All female hyenas have functional penises they use to mount & give birth.
Erect penises are a sign of submission in the matriarchal society of hyenas.
The female hyena without the erect penis is the dominant leader of the entire pack.
Editor’s note: Earlier, the author defines “penis” in this discussion as something the animal can pee through. —RXS
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.
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.
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.
In this article for Slate, bone researcher Alexandra Kralick discusses scientific research that debunks the fundamental misunderstanding that sex is a binary.
In this blog post, Gender-Inclusive Biology contributor Lewis Maday-Travis shares a presentation he created to wrap-up a unit on the skeletal system. The presentation focuses on the science of the intersex experience and nonbinary identity, both of which are supported by scientific research yet frequently erased in public discourse.
"Rosie is now in the process of figuring out her gender identity on her own terms. While she says she still likes to use female pronouns for now and wants to keep her name, Rosie says that sometimes she feels like a boy and other times, nonbinary. "Because I am both!" she said.
"Rosie's mother, Stephani Lohman, said she felt extremely pressured by the surgeons to consent to surgery even after she voiced her concerns about the procedure, including the evidence that these surgeries can have devastating side effects including a loss of sexual function, psychological trauma and life-long pain.
Pending legislation in California and New York would effectively ban these surgeries in those places by requiring informed consent from the patient before a cosmetic genital surgery.
As of 2013, the United Nations has condemned the practice on the grounds that an infant cannot consent.
Three former US surgeons general agreed, writing in July 2017, "these surgeries violate an individual's right to personal autonomy over their own future."
In 2017, Human Rights Watch concluded the surgeries violate a patient's human rights. Their research found that these surgeries can cause life-long pain, scarring, loss of sexual function, the need for life-long hormone replacement and maintenance surgeries, and psychological harm similar to that of child sexual abuse victims.
Dr. Ilene Wong Gregorio is a practicing urologist and intersex rights advocate who supports the legislation.
"Doctors have been imposing their assumptions on heteronormativity and what a child should look like, and intersex bodies, for decades," she said. "There are still people who practice outdated medicine and the only way to protect children from these people, who through culture or ignorance or hubris, are doing these things, is to actually put something in writing in the court of law."
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.
