Narrated by Elliot Page, the new documentary challenges long-held assumptions about sex and gender in nature and makes the case for bringing that science into classrooms.
Think back to your high school biology class. When you learned about how animals mate, did you ever learn about same-sex pairings? Or that some animals can change their sex? You may have heard of a few instances of queer behavior in nature—like stories of two male penguins raising an egg together, or that male seahorses, not females, become pregnant. But did you know queer behavior exists across the animal kingdom?
That’s the focus of Drew Denny’s new documentary, Second Nature. Narrated by actor and queer activist Elliot Page, the documentary explores sexuality and sex diversity in the animal kingdom and promises to teach viewers “everything you didn’t learn in high school biology.” Bringing together experts and pioneers in biology, the film paints a picture of nature’s diversity and makes the case for including these facts in high school curricula.
Denny drew inspiration and research from evolutionary biologist Joan Roughgarden’s book, Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People, which challenges traditional interpretations of Charles Darwin’s theory of sexual selection. Roughgarden argues that sex serves purposes beyond reproduction, that same-sex sexual behavior is widespread in nature, and that matriarchal and egalitarian animal societies challenge assumptions about male dominance.
“As somebody who grew up in a place where I was told that females are naturally inferior to males and queerness is unnatural, I just feel lucky that I made it to this point where I could find Joan’s book … and realize I belonged here the whole time, which is a beautiful feeling,” Denny said at an Oct. 10 screening of the film during Banned Books Week, hosted by PEN America. “I figure if I needed that feeling, other people must need it, too.”
Denny started the project in 2015, originally envisioning the documentary as a miniseries. Over the next 11 years, the project evolved into a feature film, receiving support from the Sundance Institute’s Sandbox Fund. Eventually, Pageboy Productions, Elliot Page’s production company, became attached to the project.
“When I think of this project, I just saw it and loved it so much, and it meant so much to me as a queer person, as a trans person,” Page said at the same screening. “It’s so funny. It’s so expansive. There’s such a warmth to it. And it taught me so much.”
Animals That Challenge Assumptions About Sex and Sexuality
Bonobos, one of humans’ closest living relatives, live in female-led societies. Bonobo females form close relationships with each other, including same-sex sexual relationships, and together hold considerable social power over males. Bonobos also resolve conflicts and strengthen social bonds through hugging, kissing and engaging in sexual activity.
Other animals that defy traditional expectations are albatrosses. While male and female birds often co-parent their offspring, same-sex parenting occurs, too. In one population of Laysan albatrosses on the Hawaiian island of Oahu, researchers found that approximately 31 percent of pairs consisted of two females raising offspring together.
While birds are often known for being monogamous, many species are only socially monogamous. Female birds may form a pair bond with one male while mating with others—essentially not “putting all their eggs in the same basket.” When the chicks hatch, pair-bonded birds may raise the offspring together, regardless of their biological connection.
Most birds mate through a brief touch known as the cloacal kiss. However, males in roughly 3 percent of bird species, including ducks, possess penises, allowing for penetrative sex. Duck penises can be shaped like corkscrews. Female ducks have similarly complex reproductive anatomy, including vaginal spirals that twist in the opposite direction—raising the question: How do they mate?
Researchers have found that these anatomical differences can help female ducks control fertilization: When female ducks want to engage in consensual sex, they will relax their vaginal walls to allow for the penis to fit. If the female duck is being raped, which can occur if a male does not find a partner during mating season, they can reject the penis by not relaxing their vagina walls. The shape of the vagina acts as a natural barrier to ward off unwanted mates.
Fish can undergo even more dramatic reproductive changes: In some species, such as the bluehead wrasse, females can change sex when dominant males disappear from the population. During this process, estrogen levels decline and ovarian tissue transforms into functional testes, allowing the fish to reproduce as males. In these species, changing sex is a natural part of reproductive life, and the fish that transition are embraced for helping their community grow, rather than rejected for transitioning.
While animal behavior does not map neatly onto human identities, this diversity challenges the idea that variations in sex and sexuality are somehow unnatural.
So if this diversity exists throughout the animal kingdom, why aren’t we learning about it?
Why Queer Biology Is Kept Out of Schools
The fight for LGBTQ+ inclusion in classrooms takes place against a long history of laws and policies stigmatizing same-sex relationships.
Many of the arguments against queer and trans-inclusive curricula center around the remnants of sodomy laws in the United States, which have existed since Puritan colonizers first set foot on Native soil in North America. These laws originated from misinterpretations of Christian scripture and lasted until 2003, when the Supreme Court ruled in Lawrence v. Texas that state sodomy laws were unconstitutional.
Today, so-called “Don’t Say Gay” or “Don’t Say LGBTQ” laws continue to restrict classroom discussions of sexuality and gender identity. According to the Movement Advancement Project, 18 states have laws restricting discussion of LGBTQ+ topics in school curricula (but a federal judge temporarily blocked Iowa’s law in December 2023).
Meanwhile, only eight states have laws supporting LGBTQ+-inclusive curriculum standards, and just seven require LGBTQ+ inclusion. Though this is still a huge step up from no inclusive curriculum, these standards largely focus on subjects like history, civics and social studies, rather than the biology and science classes that could help validate queer and trans students’ identities.
Research suggests that LGBTQ+-inclusive biology can make a difference. A 2026 study involving 127 high school students found that LGBTQ+-inclusive biology activities reduced rigid, binary beliefs about sex and gender and improved attitudes toward gender and sexual diversity.
Other research has found that school-based interventions, including Gender-Sexuality Alliances, inclusive curricula and anti-bullying policies, can help reduce discrimination and improve LGBTQ+ students’ well-being, particularly when schools commit to these efforts over time.
Beyond requiring LGBTQ+-inclusive social studies curricula, states should incorporate sex and gender diversity into biology classes and actively support schools in enforcing anti-bullying policies. These steps could help prevent discrimination based on gender identity or sexual orientation—and ensure students receive a more complete picture of the natural world.
How to Help
If you are an educator or a parent, you can help students and children by incorporating gender-inclusive lessons into their education. Gender-Inclusive Biology is an organization dedicated to providing teachers and students with resources to teach inclusive science lessons. It offers educator guides, lesson plans and ways for students and teachers to make a difference in their schools.
Many LGBTQ+ books geared toward children and young people also teach about diversity and queerness at an age-appropriate level.
For children 6 and under, options include And Tango Makes Three, about two male penguins who raise a chick together, and Worm Loves Worm, about two worms getting married whose friends want to know who will wear the tuxedo and who will wear the dress.
For preteens and teens, Queer Ducks (and Other Animals): The Natural World of Animal Sexuality is a great way to learn about diversity in the animal kingdom.
Another way to make an impact is to share Second Nature with your community. You can host a screening, encourage educators to incorporate the film into their lessons or simply talk about what you learned.
After all, the natural world has always been more diverse than many of us were taught. It’s time our biology classes reflected that reality.
Second Nature: Gender and Sexuality in the Animal World is available for streaming on:
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