Some years ago, I heard Doctor Daphne Yoel, a professor of
psychology and neuroscience at Tel Aviv University, speak.
When she visited Stanford, she spoke about her research using
functional MRI's to identify areas of the brain that differ
between men and women. That was interesting, but then
it got controversial when she went in search of men who
exhibited all male traits and women who exhibited all female
traits. There weren't many.
I found Doctor Yoel's research quite liberating.
It moves us past the stereotypes that we should all fit in only
one of two boxes, male or female, and if we don't, we are
somehow deviant. Her discoveries have profound
implications for how we view sexuality and gender.
This modern retelling of ancient scripture came to mind when I
was preparing this podcast. You are fearfully and
wonderfully made a multi colored mosaic.
Let me know what you think. Here to explain her research is
our dynamic duo from Notebook LM.
My apologies for their mispronunciations of Doctor
Yoel's name. It's spelled Joel Joel and they
just can't quite cope with the Hebrew pronunciation.
Enjoy. Do drop me a line.
So if I handed you like 1400 MRI brain scans, do you think you
could separate them into a male pile and a female pile?
I mean, for decades biology told us that the answer was an
absolute yes. Right.
Exactly. But our stack of sources today,
which includes neuroscientist Daphne Jewel's 2015 MRI study
and also some really fascinating rat behavioral research, says
that's basically a total myth. Yeah, it completely upends that
whole idea. It really does.
So welcome to today's Deep Dive. You are joining us as the third
person in this conversation while we explore Joel's mosaic
brain theory and, you know, really look at the liberating
implications all this has for the queer community.
So to start, the traditional rigid idea was that in utero
exposure to testosterone permanently masculinizes a brain
away from what was considered a default female form.
But Joel and her team actually put this to the test.
They analyzed this 1400 brain scans looking for what they
called internal consistency. Like if a brain has a male
typical structure in one area, does it reliably have male
typical structures everywhere else?
OK, so like if I have a male typical amygdala, which is the
region that processes fear, right?
Do I automatically have a male typical hippocampus for memory?
Exactly, and the results were pretty staggering.
Out of all those brains, only zero to 8% were internally
consistent. Wait.
Zero to 8%, that's almost nothing.
Yeah, almost nobody has a strictly male or strictly female
brain. It's just not a thing.
So instead of humans coming with two distinct operating systems,
you know, like Mac versus Windows, the brain is more like
this massive audio mixing board. I love that analogy.
Yeah, giant audio mixing board. Right, where everyone has the
same thousands of sliders, but your specific sliders are set to
completely unique levels. Yes, and crucially, those levels
don't align perfectly to one sex.
I mean, you might have the fear slider set to a statistically
male average, but then your memory slider is set to a female
average. OK, but you listening or
probably thinking, wait, if there's no set male or female
brain, how do critics explain the algorithms?
Because the sources note that critics like Check Route and Del
Giudice, they fed whole brain MRI data into machine learning
models. Yeah, they did.
And those computers could actually predict a person's
biological sex with like 73 to 93% accuracy.
So how is a computer guessing right that often if it's all
just a unique mixing board? Well, it really comes down to
what the algorithm is actually doing.
It isn't finding a single universal male blueprint.
Oh, OK, So what is it finding? It's looking at thousands of
microscopic variables across the brain and just aggregating them
to find a multivariate statistical pattern.
I see. So the algorithm is basically
looking at the sum total of tiny details to make an educated
guess, rather than like recognizing A distinct category.
Precisely. Yeah, sex from a broad
statistical likelihood is not the same thing as proving there
are two distinct cognitive types of humans.
The individual overlap is just way too extensive.
Right, so you can predict someone's sex, but you
absolutely cannot predict their unique cognitive setup just from
knowing their sex. Exactly.
OK, so if the physical structure of the brain is this unique
mosaic, is that set up like set in stone at birth?
Not at all, actually. And the rat behavioral research
in our sources illustrates this so beautifully.
They looked at dendritic spines. Oh, those are the tiny branch
like structures that connect neurons to each other.
Yeah, Yep, those are the ones in a specific region of the brain.
Male rats typically have a sparse network of these spines,
while females have a highly dense network.
And this is where it gets wild. The researchers introduced
stress. They exposed a male rat to just
15 minutes of acute stress, which is basically, you know,
the length of a bad commute. Yeah, and the physical structure
of that male rat's brain cells actually altered into the dense
female form. Wow.
What happens is that the sudden spike in stress hormones like
cortisol triggers this rapid biological reorganization in the
brain. Just 15 minutes of cortisol
completely reshapes the physical connections.
That is incredible. It really proves our brains are
incredibly plastic. I mean, the mosaic is constantly
physically adapting to our environment, our experiences and
our hormone fluctuations. So when you apply that to
identity and orientation, Joel's research intersects so
powerfully with the queer community.
Really does, because historically, psychology relied
on the flawed assumption that, say, a gay man must have a
female brain or a lesbian has a male brain.
Right, like those were the only. Options, exactly.
But Joel's work dismantles that entirely because the baseline
female brain doesn't actually exist.
The whole heterosexual homosexual binary is just as
artificial as the male female brain binary.
Yeah, and for queer individuals, or honestly, anyone who doesn't
perfectly fit society's rigid boxes, that is a profound take
away. Your variation isn't a deviation
from the norm. Variation literally is the
biological norm. Yeah, we simply aren't wired to
fit into just two categories. The data tells us that human
brains do not inherently have a binary sex.
They are a complex, ever shifting mosaic of traits shaped
by both biology and experience. Absolutely.
Which leaves us with one final thing to ponder.
We just talked about how a mere 15 minutes of stress hormones
can physically alter the so-called gendered structure of
a rat's brain. 15 minutes. Right.
So if our brains are that incredibly sensitive to the
world around us, how much of your own innate behavior is
really just your brain's physical adaptation to a
lifetime of society's gender expectations?
This is Elton Sherwin, thanks for making this podcast part of
your day. Please subscribe and recommend
us to your friends and family. Join us next time.
Meanwhile, stay safe and stay healthy.