This a tale of mice and men. And women. And trans men and women. And cis men and women. And teenagers. And people in general.
Because, regardless of our sex, our sexual orientation or our gender identity, we are all human. Strictly speaking, this tale is more about biology than about politics. But it’s about politics, too. Because politicians try to legislate human behavior. Sometimes, imprudently so.
Like now. All too commonly, politicians, religious leaders and others falsely claim that anti-trans legislation is simply recognizing the self-evident difference between “biological” males and females. After all, God created only two sexes, according to the Bible, Mormon doctrine and Mormon Apostle Dallin Oaks.
But “sex” isn’t truly binary. Even in standard textbook biology, “sex” is routinely defined in multiple, different ways. See, for example, “Sexual Differentiation of the Nervous System” in Principles of Neural Science.
“Anatomical” sex refers to overt differences such as genitalia and body hair. “Gonadal” sex refers to the presence of testes or ovaries. And “chromosomal” sex refers to the distribution of the sex chromosomes in females (XX) and males (XY).
Importantly, these three criteria don’t always match each other, and within each there are more than only two variants. Less well understood are the specifics of what might be termed “neurobiological” sex — how the brain and nervous system differ between males and females. But differ they do.
Arguably, that’s often the most important difference of all. Our brains determine who we are. Rocks don’t have brains. Rocks don’t have gender identities, either. But animals and people do.
Importantly, someone’s neurobiological sex and gender identity don’t necessarily correspond to the other three definitions of sex.
Genetic factors, social factors and nongenetic factors before and shortly after birth all contribute to determining adult brains and behaviors.
For example, consider the “sexually dimorphic nucleus of the medial preoptic area (SDN-POA)” of the hypothalamus, a neural structure implicated in male sexual behavior. Normally, it’s much larger in adult male than female rats.
But what happens if newborn female rats are treated temporarily with testosterone? As adults, they exhibit male-like sexual behaviors (mounting instead of back arching), male-like secretion patterns for sexual hormones and male-like synaptic connections between neurons in the medial POA.
Conversely, castrated newborn male rats show more female-like behavior, physiology and neuroanatomy as adults.
But, for both sexes, if the same treatments are delayed till just a few weeks later, the treatments don’t produce comparable changes.
A similar tale emerges with male rats stressed or not stressed before birth, from a study at Brigham Young University. Rats stressed before birth showed less masculine sexual activity as adults, lower testosterone levels and had smaller SDN-POAs than did non-stressed rats.
In short, early temporary hormonal exposures can have life-long, irreversible consequences on brain and sexual behavior. That’s not because rats have been indoctrinated by an LGBTQIA+ agenda.
In humans, too, neuroanatomical differences have been associated with sex, sexual orientation and gender identity. Sexually dimorphic neuroanatomical structures often differ more in quantity than quality between males and females, with considerable overlap between the two distributions. Early sensitive periods are a common developmental theme in humans and other species across multiple domains — vision, language, synaptic plasticity, learning and others.
These neurobiological realities have important practical consequences and implications for public policy. Maternal health matters. Early education matters. Pre- and post-birth nutrition matters. Often, irreversibly. But it’s unrealistic to tell a fetus or newborn infant to go work for food, no matter how much we want to encourage self-sufficiency and independence. So society steps in.
Politicians typically don’t try to override the specifics of most medical decisions in other, nonsexual domains that are less culturally charged. Correctly so. They don’t have the appropriate qualifications to make informed, judicious decisions.
They don’t have the appropriate qualifications to determine specific medical treatments for trans youth, either.
Medicine by legislative fiat too often can be highly injurious and even deadly, particularly when based on poorly informed personal and religious biases.
How would you feel if someone forced you to be the opposite sex?
Utah politicians routinely argue for reducing government interference in family life. Overriding someone else’s self-identity is among the most egregious personal violations of all.
Gregory A. Clark, Ph.D. is a professor and neuroengineer. His previous research looked at the effects of early pre- and post-birth malnutrition in rats on the adult nervous system.