Too Short for a Blog Post, Too Long for a Tweet 449

 

 

Here are a few excerpts from a book I recently read, "Eve: How the Female Body Drove 200 Million Years of Human Evolution," by Cat Bohannon.

 

One-size-fits-all doses of antidepressants are given to men and women, despite evidence that they may affect the sexes differently. Prescriptions for pain medications, too, are considered sex neutral, despite consistent proof that some may be less effective for women. Women are more likely to die of heart attacks, even though they’re less likely to have them—symptoms differ between the sexes, so women and their doctors alike fail to catch them in time. Anesthetics in surgery, treatments for Alzheimer’s, even public education curricula suffer from the ill-conceived notion that women’s bodies are just bodies in general—soft and fleshy, and missing a couple of significant nether bits, but otherwise, just the same as men’s. And of course, nearly all of the studies that produced these findings include only cisgender subjects—in the world of scientific research, there’s been very little attention to what happens in the bodies of people assigned one or another sex at birth who then go on to identify differently. In part, that’s because there’s a massive difference between biological sex—something wound deep into the warp and weft of our physical development, from in-cell organelles all the way up to whole-body features, and built over billions of years of evolutionary history—and humanity’s gender identity, which is a fluid thing and brain based and at most a few hundred thousand years old.

But it’s not just that. The fact of the matter is that until very recently the study of the biologically female body has lagged far behind the study of the male body. It’s not simply that physicians and scientists don’t bother to seek out sex-specific data; it’s that until all too recently the data didn’t exist. From 1996 to 2006, more than 79 percent of the animal studies published in the scientific journal Pain included only male subjects. Before the 1990s, the stats were more disproportionate. And this is hardly unusual—dozens of prominent scientific journals report the same. The reason for this blind spot concerning female bodies, whether we’re talking about basic biology or the nuances of medicine, isn’t just sexism. It’s an intellectual problem that became a societal problem: for a long time, we’ve been thinking about what sexed bodies are, and how we should go about studying them, in entirely the wrong way. 

In the biological sciences, there’s still such a thing as the “male norm.” The male body, from mouse to human, is what gets studied in the lab. Unless we’re specifically researching ovaries, uteri, estrogens, or breasts, the girls aren’t there. Think about the last time you heard about a scientific study—some article about a new window into obesity, or pain tolerance, or memory, or aging. More than likely that study didn’t include any female subjects. That’s as true for mice as it is for dogs, pigs, monkeys, and, all too often, humans. By the time a clinical trial for a new medication starts testing on human subjects, it might not have been tested on female animals at all. 

And that’s one of the most surprising discoveries about breast milk. Just in the last decade or so, scientists have come to realize that maybe its nutritional value isn’t the biggest deal off the top. Milk is really about infrastructure. It’s city planning. Some combination of a police force, waste management, and civil engineers. 

There’s one last point to make against the idea that mammals’ milk evolved mostly for nutrition. It turns out a significant portion of our milk isn’t even digestible. 

Modern human milk is mostly water. Among the things that are not water—proteins, enzymes, lipids, sugars, bacteria, hormones, maternal immuno-cells, and minerals—one stands out. The 6ʹ-sialyllactose that colostrum delivers to newborn baby guts is not the only oligosaccharide in breast milk. In fact, the third-largest solid component of milk comprises oligosaccharides. These complex, milk-specific sugars aren’t even digestible by the human body. We don’t use them. They’re not for us. They’re for our bacteria.

It’s been quantified, in fact: while men are nearly 18 percent faster than women in 5K races, they are only 11 percent faster at marathons, 3.7 percent faster at 50 miles, roughly even as they approach 100 miles, and then women routinely outpace the men at races 195 miles and up (Ronto, 2021).

If you put a pregnant mouse in an enclosure with a male who isn’t the father, she’ll abort (this is called the Bruce effect).

The consensus is that this capacity evolved as a response to threat since male mice will usually kill and eat pups they don’t recognize as their own. From the female body’s perspective, why invest energy giving birth to pups the new guy will eat? Cut your losses and abort. 

Once the scientific community recognized the Bruce effect in the 1950s, researchers started finding it all over the mammalian world. Rodents do it. Horses do it. Lions seem to do it. Even primates do it. 

But we humans don’t. And that’s rather telling.

Between ages two and four, you have a very difficult time sorting out all the strong emotions you’re feeling. But if having that emotionally unstable toddler brain of yours also makes you better at learning language, the gains could outweigh the tantrums. Your growing brain is engaged in a very special sort of cognitive development—building a communication engine inside the narrow window when your brain is just plastic enough to be able to wire itself for the job. 

Human brains do seem to have a cutoff for such wiring. If you learn a new language after puberty, you’re never going to achieve true fluency. You’ll be able to function. But unless you’re a very rare bird, no American is going to speak French well enough to pass as a Parisian.[*18] You can certainly brutalize an older brain into memorizing the new rules of grammar. But there’s something about how the brain learns language when it’s young that older brains just can’t do. For fluency in a second language, the cutoff ranges anywhere between ages ten and seventeen, depending on whom you ask.

Which brings us back to mothers. Among songbirds, evolution has long since optimized parent-child interactions to take advantage of the critical window. During that window, zebra finch parents, for instance, communicate with their offspring in ways that seem particularly good at teaching them how to sing. After that window closes, the parents spend much less time fussing over the kids, who slowly gain their independence. 

Because milk is part of how we make and grow babies, we mammals have a preestablished period of childhood when the mother has to closely interact with her offspring. If a mammal were to have a critical window for language learning, it would make sense for evolution to optimize for that while the child is still breast-feeding. Among modern-day hunter-gatherers, babies aren’t completely weaned until somewhere between ages three and five—precisely the stretch where their brains reach peak synaptic density and when most children’s vocabularies and grammatical sophistication explode. 

You could call it coincidence. Or you could call it a useful optimization. If humans do have a critical window for language learning, it would be useful if it coincided with the time the child has regular, necessary, up-close interaction with an adult language user. Given how expensive brain tissue is to grow and utilize, it’d also be handy to have that window coincide with a time when the child’s food supply is regular, easily supplemented, and dense with sugars and brain-friendly fatty acids. 

So when we think about the evolution of human language—how it’s actually passed on from generation to generation—it’s useful to remember that what seems to be the most critical part of the so-called critical window happens while the child is spending regular portions of the day in its mother’s arms. While there’s more collective child-care happening among humans than among chimps or gorillas, most human infants and toddlers still spend most of their time in close contact with their mothers. 

Mom, in other words, is at least half of how language happens. And she’s not passive. Not at all. Human mothers have evolved to be language engines—prodigious users and teachers of language. This is especially true during the synaptic blooming of their children’s brains.

No—sexism is one of the ways our ancestors solved our hardest problem, which, as I’ve already discussed at great length, is that we categorically suck at making babies. 

I think of sexism and gynecology as two sides of the same coin: they’re two behavioral strategies our species employed—and still employs—to try to jury-rig a glitchy system. If pregnancies are dangerous and babies are needy, you need work-arounds. For example, birth spacing to control how often the girls in your troop are pregnant. Gynecology gives you tools for birth control and abortion. But you can also create cultural rules around when and where the males get access to female bodies, and then create punishments for those who break the rules. 

That’s the core of what sexism is: a massive set of rules that work to control reproduction. The aspects shift from place to place, but every single human culture has rules about what women should wear, where they can go and in what circumstances, whom they should talk to and when, and most certainly when and how and with whom they should have sex. Each rule tweaks access to a woman’s body, shaping the parameters of her reproductive life. 

But again, let’s take a biological view here: how smart you are affects how likely you are to stay alive. If you have an IQ even fifteen points higher than the average when you’re eleven years old, you’ll have a 21 percent higher chance of surviving into your seventies. That’s a bigger boost to longevity than just about anything you can think of—bigger than what’s provided by your level of wealth and your access to medicine combined. 

As I discussed in the “Brain” chapter, your IQ is influenced by your genes, but being “smart” isn’t something you’re just born with. “Smartness” is something that brains actively do. It’s also strongly shaped by how your brain developed in the womb, in childhood, and even through the sorts of things you ask it to do when you’re an adult. Sexism can compromise the cognitive development of children in both genders. In other words, sexism makes everyone less smart. 

You might think I’m about to talk about education again. But let’s start with something even more basic: food. The human brain is literally built out of food. All the sugar, protein, and fat a fetus uses to build its nascent brain come directly from the mother’s body. So, what happens when you starve women and girls? Their future fetuses and nursing children starve, too. 

In many Indian states, it’s normal for young women and new brides to eat last. In Maharashtra, for example, the cultural rule is that guests eat first, followed by the oldest men, then the younger men, then the older women, then the children. In traditional families, a younger woman eats only once everyone else has been fed. That rule doesn’t change if she’s pregnant. 

More than 90 percent of adolescent Indian girls are anemic. More than 42 percent of all Indian mothers are underweight. And that’s not just down to poverty; only about 16.5 percent of sub-Saharan mothers are underweight. Even worse, the average woman in India weighs less in her third trimester than most sub-Saharan African women do when they first become pregnant.[*52] Malnutrition is deadly and dangerous all the time, but especially when you’re pregnant. If the mother and child both manage to survive, the newborn usually arrives too soon, too tiny, and too fragile. Many die within weeks of being born. Those who don’t usually face severe health problems throughout their lives, including problems with cognitive development. 

It’s true that pregnant women in India’s rural areas are more vulnerable to these problems. But rural Indians make up 68 percent of the country’s population.[*53] The majority of the world’s second most populous nation live in areas where there often isn’t enough food and, as a rule, pregnant women eat last. 

Sexism, in other words, is starving India from the inside out. At the same time, the country is investing a lot of its resources in a bid to become one of the biggest technology centers of the world. You need a lot of good brains to be a tech giant. Well-fed brains. To build them, you’re going to need pregnant women to jump the line at dinner. 

Now, I’m hardly the sort of person who wants to think of women as simply baby factories. But as a species, let’s say all of us want to get smarter. That’s what it takes to cure cancer. To solve the climate crisis. How do we do that? For a start, we might want to acknowledge that human brains are something that are made primarily out of women’s bodies: first in their wombs, and then from their breast milk, and then from the quality of interactions mothers have with their children. So if you want the best possible chance to make a lot of kids with high IQs, you want healthy women who are fed well, and have been fed well, consistently, for at least two decades before they become pregnant. You want them to have had a rich and well-supported childhood education. And you want them to be well cared for throughout their reproductive lives, with readily available education about nutrition and healthy habits and newborn caretaking. You want them to have community resources available when they get sick and when their kids get sick. And, because STIs have such a proven effect on reproductive health, you want them to have ready access to prophylactics and good sex ed.

There’s also a ton of evidence that more sex-egalitarian education tends to be associated with the golden ages of human civilizations in our past. Our societies seem to be at our best, in other words, when we’re educating girls. 

One well-studied example is the history of Islam in the Middle East, Africa, and Europe. By many measures, medieval Islamic societies were more gender equal than the Arab world today. In fact, the Prophet Muhammad’s first wife, Khadija—famously his most beloved—was older than him, twice widowed, already had children, and was a widely respected businesswoman when he met her.[*54] In the twelfth century, the Islamic philosopher Ibn Rushd (Averroes) wrote that women should be considered equal to men in all respects, including education and opportunities for employment. 

Remember, this is the Middle Ages. At the time, Islam wasn’t just more egalitarian than European societies. It was also more intellectually productive. Because Muslims believed reading the Quran was vital for the soul, these societies expected all children, male and female, to be literate and well educated—not just in the Quran, but in a range of topics they found valuable: visual arts, mathematics, the sciences, even music. Public education was both available and well funded. Public schooling didn’t take hold among the Christians of Europe and North America until the Industrial Revolution. If you were a child born between 1100 and 1400, you definitely wanted to be born in an Islamic society, whether you were male or female. 

The payoffs were enormous. Islam’s golden age produced algebra, chemistry, the magnetic compass, better modes of navigation, and all sorts of advancements in medicine and biology. While Europe was busy telling itself the plague was caused by an evil fog, Islamic doctors had already figured out that copper and silver instruments were best for surgery (the metals are antimicrobial). Philosophy also flourished, with new ideas about humane government and social interdependence, many of which directly influenced the rise of the European Enlightenment. The golden age of Islam, in other words, produced one of the most intellectual, egalitarian, cosmopolitan, and profoundly influential societies of its time. And women were right there at the fore, contributing to its success.[*55] 

This isn’t to say the only reason civilizations falter is that sexism rears its ugly head. Many factors contributed to the decline of Islamic nations, colonialism not least of them. And money is certainly a factor in whether a civilization is likely to be intellectually productive. (Golden ages are called “golden” for a reason.) But as of 1989, many Arab nations had become incredibly wealthy and yet managed to produce only 4 frequently cited scientific papers. The United States, by contrast, produced 10,481. Why? For one, they’d systematically cut off education for half their population. Roughly sixty-five million adult Arab people are illiterate right now, of which two-thirds are women.[*56] Many of those women live in wealthy countries, such as Iran and Saudi Arabia. Places that, once upon a time, shone with the brightest lights in human intellectual progress. But we’ll never know which of these women could have been a modern Khadija. We’ll never meet their Marie Curie, their Ada Lovelace. Whatever contributions those women and girls might have made have been sacrificed to the symbolic function of their modesty. Unless, of course, they escape these more restrictive communities and get the support they need elsewhere—but what if they can’t afford to? 

Where women are undereducated, entire societies eventually go fallow. If history proves right, neglecting girls’ education is a sign of a civilization’s decline. You can neglect half the brains in your community for only so long.