Tag Archives: neurobiology

Horses and Humans: The Unlikely Bond between Prey and Predator

Horse and rider jumping a hurdle
Photo by Gene Devine on Unsplash

Debbie says:

Horse-and-human teams perform complex manoeuvres in competitions of all sorts. Together, we can gallop up to obstacles standing 8 feet (2.4 metres) high, leave the ground, and fly blind – neither party able to see over the top until after the leap has been initiated. Adopting a flatter trajectory with greater speed, horse and human sail over broad jumps up to 27 feet (more than 8 metres) long. We run as one at speeds of 44 miles per hour (nearly 70 km/h), the fastest velocity any land mammal carrying a rider can achieve. …

That’s the opening of Janet Jones’ essay in Aeon, “Becoming a Centaur.” Jones has been a neuroscience professor and a stable owner, so she brings a beautifully doubled perspective to the topic, reminding me of Adam’s Task by Vicki Hearne, a 1986 book about training (mostly) horses and dogs from the perspective of a philosopher and poet who extensively studied animal training as well as doing it professionallly. But Hearne’s perspective was only secondarily scientific; Jones is steeped in numbers and fascinating explanations:

No one disputes the athleticism fuelling these triumphs, but few people comprehend the mutual cross-species interaction that is required to accomplish them. The average horse weighs 1,200 pounds (more than 540 kg), makes instantaneous movements, and can become hysterical in a heartbeat. Even the strongest human is unable to force a horse to do anything she doesn’t want to do.

Jones cannot get over her wonder that humans and horses aren’t enemies, and she describes quite lyrically how the connection works:

In mounted teams, horses, with prey brains, and humans, with predator brains, share largely invisible signals via mutual body language. These signals are received and transmitted through peripheral nerves leading to each party’s spinal cord. Upon arrival in each brain, they are interpreted, and a learned response is generated. It, too, is transmitted through the spinal cord and nerves. This collaborative neural action forms a feedback loop, allowing communication from brain to brain in real time. Such conversations allow horse and human to achieve their immediate goals in athletic performance and everyday life. In a very real sense, each species’ mind is extended beyond its own skin into the mind of another, with physical interaction becoming a kind of neural dance.

Jones provides a wealth of scientific detail–the differences between horse and human eyes, different communications with the brain cortexes, the art and science of subtle signals (inward pressure from a rider’s left calf tells the horse to move sidewise to the right). But the part that feels, well, miraculous, is the brain-to-brain communication:

Specifically, neural signals from the horse’s eyes carry the shape of an object to his brain. Those signals are transferred to the rider’s brain by a well-established route: equine receptor cells in the retina lead to equine detector cells in the visual cortex, which elicits an equine motor reaction that is then sensed by the rider’s human body. From there, the horse’s neural signals are transmitted up the rider’s spinal cord to the rider’s brain, and a perceptual communication loop is born. The rider’s brain can now respond neurally to something it is incapable of seeing, by borrowing the horse’s superior range of vision.

These brain-to-brain transfers are mutual, so the learning equine brain should also be able to borrow the rider’s vision, with its superior depth perception and focal acuity.

And if that weren’t enough, Jones goes on to speculate that humans may be able to transmit executive function (the ability to form expectations, make a plan, and carry out that plan) to horses, whose brains don’t operate on that level. This is unproven, but Jones gives some examples of why she believes that scientific study might find evidence.

I have effectively never been on the back of a horse, beyond a few childhood forays in those very controlled pony ride attractions. So I can only faintly comprehend the sensations Jones describes. If you’re a rider, I suspect this article will have an even stronger impact–meanwhile, I’m just going to spend some time revelling in the magic relationship between horses and humans–and the science driving the magic.

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Gender Binary Exposed Again; Replaced (or Not) with Neuroscience Binary

Debbie says:

I found a lot to appreciate in Robert Sapolsky’s thoughtful essay, “Caitlyn Jenner and Our Cognitive Dissonance,” published last week in Nautilus.

Sapolsky’s piece is in two parts. The first is an overview of why gender isn’t binary, and how complicated gender really is. Some examples:

For starters there’s plants, a number of which are “monoecious,” which is to say that any given plant has both female and male organs (those stamens and pistils). Things are stranger with animals. There are parthenogenic species, where females reproduce without males—numerous reptiles fall in this category, including the incomparably cool Komodo dragon. There are synchronous hermaphrodites where, like monoecious plants, an individual has both sexes’ organs simultaneously. This includes worms, sea cucumbers, snails, and sea bass.

Then there’s spotted hyenas, gender-bending pseudo-hermaphrodites. It’s nearly impossible to determine the sex of a hyena by just looking, as females are big and muscular (due to higher levels than males of some androgenic hormones), have fake scrotal sacs, and enlarged clitorises that can become as erect as the male’s penis. None of which was covered in The Lion King.

That section goes on to examine gender in humans:

The sine qua non of human sex designation in humans is chromosomal—all your cells either have two X chromosomes, making you female, or one X and one Y, making you male. End of story. But no: Instead, there’s various chromosomal disorders where individuals can be XYY, XXY, XXX, X, or XXYY. Most result in infertility; some, like Turner syndrome (in which there is solely an X) produce neurological, metabolic, endocrine, and cardiovascular abnormalities. …

[t]here’s numerous ways where chromosomal sex and phenotypic sex differ, accounting for 1 percent of births. This is not rare—pick a human at random and the odds are greater that they were born with ambiguous intersex genitals than they have an IQ greater than 140.

Perhaps the most interesting dissociation occurs one step further down the line. This is where the person has the chromosomes, gonads, hormones, genitals, and secondary sexual characteristics—hair, voice, musculature, facial structure, the works—of one sex. But has always felt like the other.

This is the transgendered world, and some intriguing science hints at its neurobiological bases. There are a number of places in the human brain that are “sexually dimorphic” (where the size, structure, function, and/or chemical makeup of the area differ by sex). The differences aren’t big enough so that you could identify someone’s sex just by knowing the size of one of those regions. …

And a clear conclusion …

In other words, it’s not that transgendered individuals think they are a different gender than they actually are. It’s that they’ve had the profoundly crappy luck to be stuck with bodies that are a different gender from who they actually are.

Slowly, a word becomes pertinent—“continuum.” Gender in humans is on a continuum, coming in scads of variants, where genes, organs, hormones, external appearance, and psychosexual identification can vary independently, and where many people have categories of gender identification going on in their heads (and brains) that bear no resemblance to yours. All with a frequency that, while rare, are no rarer than various human traits we label as “normal.”

On a side note, this article comes to a very closely related conclusion about sexual orientation, as opposed to gender identification. “The difference that jumps out at me right away is the new appreciation for “fluidity.” The binary view of male sexual orientation that dominated the field a decade ago has softened. Back then, there was real skepticism about men who reported being anything other than heterosexual or homosexual. After all, lab data tended to suggest that their arousal — which effectively defines sexual orientation in men — was either to male erotica or to female erotica, but not to both.”

 

Sapolsky and I part company in the second part of his piece, when he discusses human neurobiology and how he claims it locks us in to binary impressions of gender, even though he has just convincingly shown that binary gender is incorrect.

… we think categorically. And dichotomized gender is one of the strongest natural categories the brain has. The categorization is crazy fast—neuroimaging studies show the brain processes faces according to gender, within 150 milliseconds—that’s 150 thousandths of a second—before there’s conscious awareness of gender.

He illustrates this with a study dividing up various categories based on photos of basketball players. The study, for which he does not provide a reference, apparently demonstrated that jersey color overrides race as a category, but gender overrides jersey color. Because there’s no reference (and Google searching doesn’t yield anything obvious), there’s no way to tell how big this study was, how it was conducted, or any of the other ways we separate junk science from useful science.

What bothers me more is that even if this was a huge study, with great double blinds, superb statistics, and unimpeachable methodology (wanna bet?), it still has an obvious flaw: it’s single-culture. It’s about contemporary Western, probably American, sports. It doesn’t take into account the cultures that already don’t operate on a simple binary gender model. Hijras in India, berdache among Native Americans: just two examples of nonbinary gender expectations that — wow! — the brains of the people in those cultures learned (probably early, probably automatically) to recognize and accept.

Not to mention that even in the majority of cultures that do categorize gender as binary, all of them have different lines along which gender distinctions are drawn. In my lifetime, seeing a person in long pants has changed from becoming a gender marker to becoming gender-irrelevant in my U.S. culture. So has seeing a person with long hair. If recognizing gender is hard-wired and unchangeable, how have I changed those two clues inside my brain? I’ve watched young children figuring out gender, asking questions, making mistakes, learning contexts. I’ve listened to elderly native Chinese speakers, having spoken English for sixty years and completely fluent, be unable to “correctly” use gender pronouns. I see the exact same phenomenon in a friend who had a bad stroke.

Sapolsky is putting way too much weight on a few bits of neurological data, and ignoring the vast range of data which don’t fit his thesis. He says,

It’s difficult to imagine, though, any strong selective pressure against our brain’s automatic binary categorization by gender—it can be handy when it comes to that evolutionarily relevant goal of finding a mate. Accepting the fragility of that categorization requires some heavy lifting by the neocortex, the recently evolved, egg-heady part of the brain that is tasked with assimilating the information in an article like this. In 35 years, most of us will still be sniffing at crotches, asking, Boy or girl?

I agree with him that the industrialized world is not going to stop trying to fit people into “women” and “men” any time especially soon. And I even agree that there are evolutionary advantages to knowing “boy or girl”? At the same time, I believe that we can change that, and that the possibility of that change, and the seeds of how it can happen, and is happening, are everywhere if we look for them.