Repercussion Section: Science Like A Girl
By Sandra Steingraber, SEHN senior scientist and writer in residence
In 1987, via Public Law 100-9, Congress declared the month of March as Women’s History Month. In subsequent years, Congress passed additional resolutions that authorized the President to rededicate each March thereafter as a time to celebrate the contributions of women in history and society.
And each March since 1988, the sitting President has so declared it. Including this year.
Each year has a dedicated theme. In March 1987, the theme was “Generations of Courage, Compassion and Conviction.”
In March 2018, the theme was “Nevertheless, She Persisted: Honoring Women Who Fight All Forms of Discrimination,” throwing some shade at Senator Mitch McConnell and his intended-to-be-disparaging remarks about Senator Elizabeth Warren.
In March 2023, the theme was “Celebrating Women Who Tell Our Stories,” and, to enact it, U.S. Air Force 37th and 76th Airlift Squadrons commemorated the role of women in the story of aviation by staging a Fly Like a Girl event at the Ramstein Air Base in Germany in which female Airmen operated C-130J Super Hercules and C-21A aircrafts as part of an all-women’s formation.
Last year, March 2024, the theme was “Women who Advocate for Equity, Diversity & Inclusion.”
Oh.
And this year’s theme, as declared by the current President: “Moving Forward Together! Women Educating & Inspiring Generations.”
So, in 2025, women are being honored for… homeschooling?
The slogan decidedly feels like a move backwards, despite the exclamation point. Or maybe it should be called “Moving Ironically Together!” in light of the purge at the U.S. Department of Education where more than 1,300 federal employees lost their jobs last week.
Also, in time for Women’s History Month 2025, the White House removed from all official websites the U.S. Air Force photo of the Fly Like a Girl air crew from two years ago. (The “page not found” message in the link above is the message you’ll see on all the U.S. government websites when you search for this image.)
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Here at SEHN headquarters, we have been watching the ongoing dismantling of two intertwined systems—policies that are protective of public health and the body of science that informs these policies—and we are doing our best to step into the breach (as described in the Editor’s Note by Carmi Orenstein above).
The attack on public health science takes three forms: the disappearance of research that has already been done—as when Centers for Disease Control databases are taken offline a la the Fly Like Girl U.S. Air Force photograph; the defunding of scientific research that has yet to be completed; and prohibitions on federal agencies from using science to make decisions.
Consider that there are two bills before Congress now that would forbid the U.S. Environmental Protection Agency (EPA) from using the results of hundreds of assessments of toxic chemicals completed by its Integrated Risk Information System (IRIS) program.
IRIS data is used to help the EPA create environmental rules and regulations, decide on enforcement actions, or issue permits that limit the levels of chemical contaminants allowed in air and water. IRIS assessments estimate, for example, the concentrations of various chemical exposures that can trigger cancer formation.
As reported by journalist Sharon Lerner, the EPA would also be prevented from using IRIS data to map the health risks from toxic chemical exposures. “If it becomes law, the ‘No IRIS Act,’ as it’s called, would essentially bar the agency from carrying out its mission.”
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On top of these direct assaults, science is harmed via the ongoing vilification of diversity, equity, and inclusion initiatives, which strongly influence who gets to do science in the first place.
My own dissertation topic in ecology was focused on white-tail deer, specifically on the feeding behaviors of does and how their dietary choices shaped the species composition of forest ecosystems. Does in winter congregate together, and, because they are almost always pregnant, they have particular micronutritional needs that differ from their male counterparts and, accordingly, seek out different twigs and buds to feed on.
By contrast, bucks are solitary and overwinter by themselves.
It turns out that pregnant does strongly influence the species diversity of their forested habitats in ways that bucks do not.
I would not have pursued this line of inquiry had my doctoral advisor, community ecologist Beverly Rathcke—the only tenured woman in my department at the time—not strongly encouraged me. I quickly discovered that, in the scientific literature on deer, there were many more papers funded and published on the growth patterns of male antlers than on the biology of female deer altogether and there were almost none about their feeding preferences during pregnancy.
And that’s because large-mammal biology has historically been dominated by male biologists who grew up hunting, and antlers are culturally significant masculine trophies.
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So, to commemorate Women’s History Month this year, I’d like to shine a little spotlight on an early 20th century biologist, Nettie Stevens, the discoverer of the two chromosomes that all kinds of people who otherwise disparage science claim to understand deeply and currently invoke as having primacy over everything: the ones named X and Y.
Nettie Stevens, 1904. Source: TriCollege Libraries Digital Collections
Nettie Stevens studied the sperm of mealworms. In 1905, she figured out that the sperm cells that had a small version of the 20th chromosome would, when they fertilized a mealworm egg, produce male offspring. The ones that had a large version made females.
From her monograph: “The spermatozoa which contain the small chromosome [determine] the male sex while those that contain 10 chromosomes of equal size determine the female sex.”
Prior to Stevens’ discovery, which was rooted in Mendelian genetics, the dominant view was that various environmental factors influenced sex and gender. In humans, for example, the thinking was that the diet and sleeping habits of the pregnant mother—including which side she preferred to lie on—influenced whether the baby would be a boy or girl. This assumption, based on no evidence at all, doubled as a convenient way of blaming women for, say, failing to produce a male heir.
Aristotle, for example, asserted that heat determines its biological sex. Specifically, he argued that all embryos are meant to develop into males, but those without sufficient heat suffer arrested development and become females.
You might even say that, before Nettie Stevens’ 1905 book Studies in Spermatogenesis, with Especial Reference to the “Accessory Chromosome,” sex and gender were understood as fluid states that could easily transition from one to the other.
Stevens did not get credit for her work during her lifetime. She died at age 50 of breast cancer. She never married.
Science, of course, marches on.
Nearly 120 years later, we now understand that the determination of sex and gender are far more complex than the simple possession of an X or Y chromosome.
We know that the human body, no matter what the underlying genetics, will develop a female appearance unless it is changed by the two hormones secreted by the fetal testes.
We know that intersex individuals are more common that previously appreciated and that it is also possible to be XX and look male in appearance and XY and look mostly female.
We know that a constellation of other genes determines the sensitivity of cells to testosterone and that this sensitivity guides the development of sexual anatomy.
We know that the sexual differentiation of the gonads and the brain happen at two very different points of pregnancy and can indeed be influenced by environmental factors.
Nettie Stevens was right about the sperm of mealworms. They can carry X or they can carry Y.
But the vicious culture war unleashed by political leaders who assert the sole biological determinism of X and Y chromosomes while in the next breath ordering the destruction of our nation’s scientific research institutions are not acting in good faith.
Happy Women’s History Month to the brilliant geneticist Nettie Stevens who could not have imagined where her discovery would land. It’s not your fault, girl.