All XX Spanish Moles have ovotestes (both ovarian & testicular tissue) and make Eggs & Testosterone, but XY moles only have testes & Make Sperm. (Gender Showcase, 9-12)

Talpa occidentalis (mole, Iberian peninsula)

All females have ovotestes (ovotestes are gonads containing both ovarian & testicular tissue) XX have ovotestes & make eggs and testosterone only, XY have testes only and make sperm only.

Image caption: A Spanish blind mole emerges from underneath a rock. Photo credit (C) Tiago Magalhães.

Most gender-gene committees, with or without the presence of SRY, pass a resolution creating only a testis in males and only an ovary in females. In some species, though, even this most elemental aspect of bodily gender has been given a different configuration.

Among Talpa occidentalis—another burrowing mammal, an old world mole from the Iberian peninsula—all females have ovotestes, gonads containing both ovarian and testicular tissue. The ovotestes occur at the site in the body where simple ovaries are found in other species. 

Talpa XX individuals have ovotestes and make eggs in the ovarian part of their ovotests. They don’t make sperm, but they do have both sperm-related and egg-related ducts. The testicular part of these ovotestes secretes testosterone. XY individuals have testes only and make sperm.

References

• R. Jiménez, M. Burgos, A. Sánchez, A. Sinclair, F. Alarcón, J. Marin, E. Ortega, and R.D. de la Guardia, 1993, Fertile females of the mole Talpa occidentalis are phynotypic intersexes with ovotestes, Development 118:1303-11.

• Roughgarden p. 202

4 Ways Biology Can Make Your Teaching More Inclusive

When I switched to science teaching, I worried we weren’t preparing students for the diverse professional work environments I had left. Peers from different backgrounds often struggle to work together, and some curriculum can limit, not expand, the student conversation.

A student says…

• “You need a mom and dad to make a baby.”

• “Same-sex pairings or transgender behavior is unnatural because they don’t produce babies.”

• “My textbook says a characteristic ‘goal’ of life is to mate and have biological children.”

• “But I was taught that everyone is XX or XY. Is that wrong?”

What do we say?

Even in San Francisco, more experienced teachers asked me, a nonbinary immigrant biology teacher, whether science had any unbiased resources for talking to students in a gender-inclusive way. I’m passionate about creating a classroom where students can stay curious about new experiences and identities, but I still want to keep science at the center.

To get you started, I’m sharing four ways teachers at any level or subject can respond to common gender-related questions using the evidence-based model of actual scientific research. Click through to read the article on WeAreTeachers, which includes the infographic below. Feel free to print and/or share!

–RXS

80% of gay swan couples successfully raise their young, compared to 30% of straight swan couples. (Gender Showcase, 9-12)

Life-long pair-bonded male-male couples of the species Cygnus atratus will raise an egg together donated by a female.

Male-male black swan parents are more successful.

80% of gay black swan couples successfully raise their young, but only 30% of straight swan couples successfully raise their young.

Black swans (Cygnus atratus) also form stable male-male pairs that last for many years. Gay swans may even raise offspring together as a couple. A female may temporarily associate with a male-male pair, mate with them, and leave her eggs with them.

By sharing the workload more equally, male-male parents access better nesting sites and territories than straight couples.

The male couple then parents the eggs and is reported to be more successful than a male-female couple because together they access better nesting sites and territories, sharing the workload more equally than between-sex couples.

A full 80-percent of the gay couples successfully fledge their young, compared with 30 percent for straight couples. (EN19)

(EN19) L.W. Braithwaite, 1981, Ecological studies of the black swan: III. Behavior and social organization, Australian Wildlife Research 8:135-46.

Citation: Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. p. 136.

Update (5/24/23): Thanks to J. Boeheme at Science TV Australia for clarifying these papers are about black swans, not all swans.

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.

The sex-changing Australian goby species have 2 sexes: all-female or part-male-part-female. (Gender Showcase, 9-12)

Image credit: Yellowfin Goby, Acanthogobius flavimanus, in Jawbone Marine Sanctuary, Williamstown, Port Phillip, Victoria, February 2018. Source: Wayne Martin / iNaturalist.org. License: CC By Attribution-NonCommercial.

Edit (6/23/21): The book excerpt uses “gender” when it talks about morphology (body plan) in the Barlow study. Thanks to reader Breanna H. for asking about a previous draft of this post that repeated the book’s wording. I learned recently how much K-6 material leans on gender norms to explain biological things. Models are always imperfect, and Breanna refers to a teaching approach that avoids applying the human concept of gender to animals, and a discussion about the risks in conflating sex and gender in animal model studies. (-RXS)

Edit (6/8/23): Thanks to Wayne, adding this: 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!(-RXS)

A species of goby from Lizard Island on Australia’s Great Barrier Reef [is the Australian goby].(EN12) In the Australian goby, all the juveniles mature into females, with some later becoming males. The males, however, can change back into females. In fact, the meaning of male is ambiguous here. The investigators defined a male to be any fish with at least some sperm production. All males, however, contain early-stage oocytes—cells that develop into eggs—in their gonads. So all the males remain part female. The species therefore consists of two genders at any one time: all-female fish and part-male-part-female fish.

(EN12 G. Barlow (2000) The Cichlid Fishes: Nature’s Grand Experiment in Evolution. Perseus.)

Citation: Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. pp. 137-38.

All bighorn rams that mate with ewes participate in gay courting & copulation most of the year. (Gender Showcase, 9-12)

Bighorn Sheep

1. Males (rams) & females (ewes) live separately except during breeding season.

2. Females are only sexually active 3 days of the year! They refuse all other approaches the rest of the time.

Book excerpt:

The males (rams), with large thick horns that curl back from above the eye to behind the ear, weigh up to 300 pounds. Their macho appearance has become a symbol for many male athletic teams. The females (ewes) live separately from the males. The sexes associate only during the breeding season, called the rutting season, which extends from mid fall to early winter. A female is receptive for about three days, and will not allow herself to be mounted outside of these three days. (EN29)

(EN29 ) V. Geist (1971) Mountain Sheep: A Study in Behavior and Evolution, University of Chicago Press; J.T. Hogg (1984) Mating in bighorn sheep: Multiple creative male strategies, Science 225: 526-29; J.T. Hogg (1987) Intrasexual competition in and mate choice in rocky mountain bighorn sheep, Ethology 75: 119-44.

All male bighorn sheep that breed with female ewes also participate in homosexual courting & anal copulation.

Book excerpt:

The males have been described as “homosexual societies.” Almost all males participate in homosexual courting and copulation. Male-male courtship begins with a stylized approach, followed by genital licking and nuzzling, and often leads to anal intercourse in which one male, usually the larger, rears up on his hind legs and mounts the other. The mounted male arches his back, a posture known as lordosis, which is identical to how a female arches her back during heterosexual mating. The mounting male has an erect penis, makes anal penetration, and performs pelvic thrusts leading to ejaculation.

Source: Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. pp. 137-38.

article excerpt:

Four behavioral phenotypes have been described in domestic rams raised in all-male groups: female-oriented, male-oriented, bisexual, and asexual. To make behavioral assignments, rams are first given sexual performance tests, also known as serving capacity tests, to determine whether or not they are attracted to females and to get a measure of their sexual performance.

Source: Roselli, C. E., Reddy, R. C., & Kaufman, K. R. (2011). The development of male-oriented behavior in rams. Frontiers in neuroendocrinology, 32(2), 164–169. https://doi.org/10.1016/j.yfrne.2010.12.007.

Bighorn Sheep have 3 behavior-based genders & 2 body types:

1. Female-body ewes live separately from gay male rams and only accept mounting 3 days of the year.

2. Male-body rams live together separately from females and copulate anally with other male-body sheep most of the year.

3. Male-body rams that live with female-body ewes most of the year and refuse mounting by other male-body rams.

Book excerpt:

The few males who do not participate in homosexual activity…are identical in appearance to other males but behave quite differently. (EN30) They differ from [so-called] “normal males” by living with the ewes rather than joining all-male groups. These males do not dominate females, are less aggressive overall, and adopt a crouched, female urination posture. These males refuse mounting by other males. In physical appearance, including body size and horn development, these males are indistinguishable from other males.

(EN30) J. Berger. (1985) Instances of female-like behaviour in a male ungulate, Anim. Behav. 33:333-35.

Citation: Roughgarden, J. (2013) Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press, Berkeley. pp. 137-38.

Species: Ovis canadiensis (wiki)

Range: North American (Rocky Mountains, Sierra Nevada, southwestern US, Mexico)

Heteronormative safety policies, violence, & harassment at schools cause decrease in perceived safety for gender-nonconforming students in 28 high schools. (J. Adolesc)

Heteronormativity, school climates, and perceived safety for gender nonconforming peers.

Abstract

Students' perceptions of their school climates are associated with psychosocial and academic adjustment. The present study examined the role of school strategies to promote safety in predicting students' perceptions of safety for gender nonconforming peers among 1415 students in 28 high schools. Using multilevel modeling techniques, we examined student- and school-level effects on students' perceptions of safety for gender nonconforming peers. We found that older students, bisexual youth, Latino youth, and youth who experienced school violence perceived their gender nonconforming male peers to be less safe. Similarly, we found that older students and students who experienced school violence and harassment due to gender nonconformity perceived their gender nonconforming female peers to be less safe. At the school-level, we found that when schools included lesbian, gay, bisexual, transgender, and queer (LGBTQ) issues in the curriculum and had a Gay-Straight Alliance, students perceived their schools as safer for gender nonconforming male peers.

Citation

Toomey et al. (2012) Heteronormativity, school climates, and perceived safety for gender nonconforming peers. Journal of Adolescence. 2012 Feb;35(1):187-96. doi: 10.1016/j.adolescence.2011.03.001. Epub 2011 Apr 8.