288. Bitch: On the Female of the Species (2)
2 (11m 51s):
That's a long time ago. Right. I mean, and with still was still believed that females are not sexually strategic. I mean, you turn on, you turn on the television. I mean, I can't even watch it watch natural history documentaries anymore. It's been completely ruined for me. It's just the sort of perpetuation of these ideas is just, you know, it's all told from a male narrative, you know, as, as a females are just the sort of passive victims to the, to the male story. And it, I'm just kind of amazed that, you know, this started questioning this back in the late seventies, early eighties, and we're still fighting to have these myths over time. I mean,
1 (12m 32s):
Right. All those David Attenborough documentaries, they're so beautifully and well produced, but you know, whatever, I don't even know what the biases are there. I don't know if you've seen the little meme video somebody made of his voice, describing the Russian tanks, migrating all the way from the hinterlands of Russia, to the Plains of Ukraine, where they go to D this is the Russian tank, like the spawning salmon. They traveled to Ukraine where they all die. It's really funny that voice, I can't do that voice, but yeah. So, right. So let's start with, with the deepest question. Why or why is there sex? Why are there males and females? Why can't we just clone or, you know, do parthenogenesis or colonial or whatever, you know, what's the origins of sex and why do we have it?
2 (13m 18s):
Oh, I mean, that's, that's, that's been dubbed the queen of all questions, doesn't it? I mean, that's, that's, that's one of the biggest questions there is start, start me off on an easy one. Well, so, well, you know, traditionally we we've, we've said that the reason why, you know, sex evolve was, was two-fold right. Sex does two jobs, one, it creates variation. It creates novel variation when sperm and egg come together, that they have half the amount of genes of, of a full genome and in each and sperm and an egg. And so together, this recombination creates variation. So that's number one, and we need variation in order to evolve and to adapt when you environment number two, it stops the buildup of deleterious mutations, and what's called ominously mutational meltdown, which happens when too many, too many bad mutations build up.
2 (14m 12s):
And it allows those to get switched out. So sex does these two jobs and you know it, but there are, as I talk about in my book, which is kind of fascinating, there are all these species where, and so it's, so the idea is, is that a species that cloning them? So, so th the first, originally, you know, the first life before sex cloned itself, but that also means by the way, the first life was female, because it made X. So that's something know that doesn't get it, doesn't get banded around a lot, but that's, that's widely considered that, that, you know, if you were going to give a sex to, to the first, to, to, to the first organism, they would, they would have to be female because they were producing eggs and then came along second and David Cruz at ship university, who's retired now, the university of Texas, he he's actually gone back and he would, they looked for the oldest transcription factor in Eastern region and found that that was, I'm going to have, I'm going to get the numbers wrong now, but it's something like 750 million years old.
2 (15m 21s):
And the testosterone transcription factor didn't come for another three, 400 million years. So, so definitely he thinks that females were the original sex and that, and the, and the, and th that, and that's males and sperm came along afterwards. So what, what we find is, is actually that this, this, this sort of, there are quite a few species that, that do very well with cloning. So there's this idea that, that, that females would need, it would need sex in order to switch it up. And the idea that if you're an asexual creature, you've got an, even a shelf life of about a hundred, hundred thousand years, but there are a number of species that we now know of most notably the Delloyd rasa for, which is a small relative of the flatworm.
2 (16m 9s):
Hasn't had sex for 80 billion year, 18 million years. You know, there's, there's a lot, I mean, dry patch, but she's doing fine. So she's like, you know, John May not Smith. We call such a creature, an evolutionary scoundrel, you know, because they call into question the whole place of sex.
1 (16m 28s):
Right? Yeah. So, and that brings us to the deeper question then what is a female? What is a male? You probably know, there's this movie going around, that came out last week. What is a woman by the conservative commentator, Matt Welch, where he, I haven't seen it yet. I just saw the trailers where he seems to, dumbfound so many people who can't answer the question. I don't know if it's, it's a bore at like gotcha. Type editing, you know, where anybody can be made to look stupid, obviously the context, but how, how do biologists define a female or a w what does a woman, what does a man, how do you answer that question?
2 (17m 5s):
I haven't seen that video. I'd love to see it. So, so I, don't my book just first and foremost, my books about animals, right? So I'm not writing about humans. That's not my specialty, Amazon ologists. Right. So, but to answer, what's the question of what is a female? You think it would be a really straightforward thing. Most people would say, oh, it's defined by the genes, or, you know, genitals, or, you know, or finally all go nuts. Right. So, but actually putting, putting marshaling, you know, the animal kingdom into one of two neat binary buckets becomes actually quite problematic. So the question of what is a female is, is, is really interesting, right? So, you know, first of all, you know, you, you, you sort of think, you know, most, most of us learn in high school, don't we, that the males are X, Y, and females are execs, and you sort of think, okay, that's like, you know, that that's a standard way of sort of defining the sex is, is genetically.
2 (18m 6s):
And, and you think that the genes that make them male, that, that, you know, are on the why and the genes that make her a female are on the X chromosome, but why was completely astonished to discover? And, you know, I, I studied genetics at university as well. So, you know, but this is sort of, you know, what we're finding out now is this, these two pathways to becoming male or female, which are always thought of as linear and distinct. Yeah. Because you have in mammals, you know, the, the, the fetus, the fetus is sexually neutral to start off with. And then there's a trigger that starts one of these two pathways. So that the, the embryonic gonad becomes either a testes or an ovary, right.
2 (18m 53s):
In the humans. The trigger is the presence or absence of the Sr Y gene. But what fascinated me, I spoke to Jenny graves, who's this amazing, she's now in her eighties. And she's decoded the sex, sex chromosomes of everything from plastic to nematode worms. I mean, she's just like, she's an extraordinary, she part of the team that found the SROI gene. So, you know, she explained it to me, but yeah, so we always thought that these two pathways to becoming male or female are linear and distinct. He's like, they're not, they, they are meshed. So they basically work on tokenistic early. So, you know, the, the, the pathway to making a testes also is suppressing and ovary at the same time.
2 (19m 37s):
And the thing that really blew my mind to discover is that the genes involved in creating either a testes or an ovary, aside from the trigger gene, they're the same 60 genes in males and females. They just play to a different, I actually had to ask her three times I had to speak to her on three separate occasions. Cause I just, and, but then that, but, and then, so, so this, this sort of mush of kind of, you know, these pathways that are in meshed and they work antagonistic in one has this, this repression, they found, you know, 1, 1, 1 system re suppressing the other continues into adulthood. They found in mice now.
2 (20m 18s):
So this sort of, you know, that the testes is actively suppressing the ovary. You know what this does is it throws up tons of variation. And of course that's what, that's what you want. It's what evolution, you know, feeds off. It's the grip that drives evolution forward. So you end up with these incredible creatures, like the mall, for example, like the female mole, we're all familiar with moles, you know, probably got them in your guard and drive you mad. Well, tell you something about moles. It's not very easy. Living underground, got not a lot of oxygen to breathe. Lots of toxic waste gases, really hard digging for a living. So th the evolutions, given the mole, like some amazing adaptations, they got an extra thumb.
2 (20m 59s):
They can dig hard, they can process waste gases more effectively, but the most amazingly about the female mole bulging male gonads, she's got OVO testes that are, that are half ovarian and half testicular tissue. And the, you know, in the breeding season, the ovary side chucks out eggs, but outside the short breeding season, the testicular tissue produces tons of testosterone and it, and it makes her really defend, you know, defend their pups really aggressively and, and dig really hard. So, and, and makes also makes by the way, her vagina seals are outside of the breeding season. And, and so, you know, on a gonadal genital and hormonal level, she would appear to be a male, you know, but she's actually a female.
2 (21m 43s):
So, you know, this question of what is a female that, you know, th there's there's, it's a little bit, the kind of standard markers are, are, are very blurry. And, you know, but generally biology says that, you know, the biological definition of sex is that males are produce sperm and females produce eggs, but then, you know, you get creatures like the frogs that I, you know, they used to, I used to catch in my garden when I was young and that they have genetic sex determination, but then they also have environmental sex determination, which overrides the genetics X, the termination. So you get X, Y females and XX males, and they're going, ads are a mixture of, of, of, of testicular and ovarian tissue.
2 (22m 29s):
And so it becomes really tricky where you draw the line.
1 (22m 33s):
Right. So would that be an example, your 60 genes determining sex? Would that be an example of epigenetics where the genes are being turned on or off, depending on the environment?
2 (22m 45s):
Yeah. And epigenetics is definitely involved in it. I mean, it, it's, it's, it's a, it's a huge complex process of, of checks and negotiations and energy and negotiation. So yeah, the, you know, the, the effect of one gene passes onto the next, and then that feeds back and it's wildly complex.
1 (23m 7s):
Right. So
2 (23m 8s):
Well, and, and certainly epigenome.
1 (23m 11s):
Yeah, exactly. Right. So, I mean, you often hear that mammals never changed sex, but moles or mammals, but are they changing sex or maybe that's not even the right way to say it or even ask it,
