Virgin Birth

constructing a major and Nativity scene. Okay, and of course you have to have your various animals present, and and so we've been arranging the animal and I guess others bearing gifts of of nursery web spider style wrapped up packages of dead insect husks and sticks and stuff. I don't know who the shepherds would be. Well, whatever the shepherds are, we know that at the heart of the of the Nativity you have to have that that baby Jesus. Granted, we did an episode last year on the Baby Jesus

homunculus and that is rerunning this year. But at the heart of this story of the Christmas story and Christian traditions is the story of a virgin birth. Now, the story of a miraculous birth, of course, is very common in in mythology and legend around the world. A god being the father of a famous or heroic person is a very common motif to appear wise settle for an earth dad when you can have a cosmic dad. Yeah,

it's a it's it's a time tested story. Right. You have your demigod heroes that are that that have have we at least one parent that is of divine lineage. Now, before we go any further, I do want to just summarize the Christmas story as it's presented in Christmas Christian traditions, just really quickly here, so it's probably familiar to a lot of you. You have a first century BC woman by the name of Mary, and she finds out via angelic visitation that she's destined to become a first century

CE mom, and not in the way she'd plan. No, instead of using offspring via relations with her husband Joseph, she has been impregnated by the High God. She is a virgin, but will give birth to a divine son.

And like you, said, this is not an anomaly in global myths, legends, and religions, we have other stories of some sort of miraculous birth taking place, right, And what we wanted to focus on today was the fact that though this may in fact be some form of miracle if it were to actually happen to a human being, in other corners of the natural world, stories like this are actually not all that miraculous. They in fact happen all the time. Right. So today we're gonna be talking

about parthenogenesis. That is the the scientific term for what's occurring here. It's taken from the Greek words parthenos meaning virgin, and genesis meaning origin. So this means in the animal world, or in the world of sexually reproducing species, a female that reproduces without fertilization by male sex cells, right, And it occurs pretty commonly among lower plants and invertebrate animals,

particularly rotifers, a fids, ants, wasps, and bees. I do want to hit just two of my favorite examples from the invertebrate invertebrate world. First of all, in the termite world is pointed out in a two thousand nine research

paper from North Carolina State University. Certain female termite primary queens of the species Radical Attorney's Separatus reproduce both sexually and a sexually during their lifetimes, sexually with the male kings, and a sexually to essentially clone themselves to create secondary queens. And these are the successor queens that will then mate with the king, So it's important for them to have no genes in common with them. So that's just I think,

a fun example. All right, Well here you can you can clearly see in this picture why it is advantageous to use a sexual reproduction alongside sexual reproduction. Of course, the greatest benefit of sexual reproduction is that you get some variety in there. You don't have the a stagnant gene pool right sexual recombination. If you were just making copies of your own genes over and over again, it becomes much easier for say, parasites to find exploits with

your body. But if you're constantly randomly recombining your genes with other members of your species, then you add some diversity to the mix and give yourself more room to more genetic wiggle room. It's kind of like say Hollywood made the same movie for ten years straight, Like the same, say superhero movie, just the same one time after time, and it was a really tremendous design. Everyone loved it. But then suddenly everyone's decides, you know, not that into

superhero movies anymore. Bam, an entire decade wasted. Right, that's a very loose um explanation, but but that's why you get the genre mix up. Throw some zombies in there. No, and now you got a whole new thing. Now it's fresh again. Yeah, and now people will get into it. Uh. Here's another example that I love. This is probably my absolute favorite. It's a particular type of Amazonian ant micro Capris Smithy, like Alan Smithy speaking films. Uh. This is

a fungi growing species. It's not unlike the leaf cutter aunt and they've actually given up on sexual reproduction altogether and have become an all female species. It's a colony of clones, so there are a lot more efficient in some ways, but they're highly vulnerable due to their lack of gene diversity. But they're an example of a species that took a reproductive tactic that existed in balance with sexual reproduction and eventually made it their own. Means. They're

only means of reproduction. Now, while this might be more common and of course a sexual reproduction is the norm amongst a like single celled organism, but while it may be more common among invertebrates and these sort of what are considered lower order animals, though I don't know if it really makes sense to consider them lower or higher.

What does lower or higher means? But anyway, it is going to be more surprising to find something like this in vertebrates, which normally would expect to be sexually reproducing animals. You've got a backbone, you should be having sex, right, yeah, I mean that's why it's such a rarity. Roughly seventy backbone species have been known to engage in parthenogenesis or

exhibit parthenogenesis. That's a roughly point one percent of all vertebrates. Now, just a few basic category categories of parthenogenesis before we move on to specific examples. Uh, there's accidental. This is spontaneous parthenogenesis. Uh, it's not part of the plan, not part of the plan, but it does occur. And one example we'll see that later is in sharks. There's also facultative. This is when a female can produce offspring either sexually

or via a sexual reproduction. Um, this is a common example, but one that we'll look at here in a minute is komodo dragons. And then there's obligate Uh, this is exclusive a sexual reproduction. That doesn't mean that a given species can't use sexual reproduction, but it's certainly not their primary means of reproduction. So, you know, think of the various invertebrates as an example of this, including the ants that I mentioned earlier. Single sex species, yes, especially especially

single sex species. Well, let's take a look at those komodo dragons. Yeah, so the komodo dragon, which is Verona's komodo insists, is of course the largest lizard species in the world. And Robert, I don't know about you, but this was one of my favorite animals when I was a kid. I could not get enough of them. I love pictures of them. I think I would actually if I could get like a national geographic with a picture of one, I would cut it out. I seem to

have some memories of that. Oh yeah, because it's the really it's the closest thing you can get to to a storybook dinosaur, like not counting not getting into like, you know, the the evolution of avian species and all that, But just in terms of like, I want a giant lizard creature like I see in my children's books. This is the closest you're gonna get. So yeah, I remember being super into it. I remember being like weirdly excited when I think was it Kim not Kim Baysinger, Sharon

Stone's husband was bitten by one. I just remember being in thee and yeah, not to make light of that, I mean, I'm thinking that now it's probably horrific, but I remember the time it was like, oh my goodness, the Komodo dragons are coming after our celebrities, Like there was something weirdly exciting about that. And yet at the same what if they get Richard Gear. No, not Richard Gear.

He's a national treasure. But in terms of seeing them in zoos, though, this is one of those animals it is both impressive and boring to see in most zoos because it's a it's a cold boded creature. It's it's just going to be sitting there most of the time. An impressive organism, but very little movement unless you're lucky. At the same time, there's there's some tremendous footage of them in the wild. If you've watched any of the the BBC Earth documentaries, you've seen some of this footage

of of the active Komodo dragon. And there's nothing, there's nothing more terrifying than watching them, say, move in on a on a a vulnar horble cow that is trapped in the mud. Have you ever watched them doing acrobatic barfing? Oh, they're quite They are quite adept at barfing, aren't they unbelievable barfing? Like there, I've seen footage of them barfing where it looks like they barf up more than their

own body mass. They are also Remember one of the notable things about them is that they will sling intestines around to remove the fecal matter from them so they can eat the intestines. Okay, I don't think i've read that, but I think maybe i've heard you mentioned that before. Yeah, yeah, they're they're voracious eaters. So the young commodo dragons have to hide from the adults so they don't get eating. I believe they climb trees, and of course the grown

ups cannot really go after them. Yes, they can be quite aggressive, even to one another. So this species. They live on a number of islands in Indonesia, and as adults they get huge. They can grow up to about three meters or tin feet in length. Actually, I think the UH the largest one ever I read was even bigger than that. It was like tin point three feet in length, and they can weigh over a hundred and

thirty kg or about three hundred pounds. Again, I think I read that the biggest one ever measured was something like three hundred and sixty pounds. They are venomous. They deliver a bite that prevents the praise blood from clotting. However, they do not primarily hunt live prey, because the majority of their diet from scavenging dead or dying animals, though of course they do also hunt, and when they hunt

live prey. Those prey species can be all kinds of things, mainly dear, I think dear is the biggest one, but also bovines, pigs, rodents, monkeys, goats, and they have on occasion, as we said, attacked and killed humans. But this does not make them our enemy. These are magnificent scaly beasts, and they themselves are threatened in conservation status terms, you know, like you got the UH the i u c N classifications, they are not yet considered endangered, but they are considered

vulnerable according to the w WF. They're only about six thousand and left on Earth and only about three fifty breeding females, and for that reason there are these conservation and captivity breeding efforts going on around the world. But so I want to tell a komodo dragon story. In two thousand five, a female komodo dragon named Sung Guy was living at the London Zoo and that year she produced a clutch of twenty two eggs, four of which

were viable. But there was a problem. It had been two and a half years since Sung Guy had been anywhere near a male komodo dragon, so in order in order to explain her laying these eggs, it would seem she either had to somehow store sperm from a male for over two years, which is technically possible sometimes in reptiles there are like sperm storage methods that sometimes happen, or she had performed parthenogenesis and her eggs hatch seven and a half months after she laid them, and her

offspring seemed healthy. Uh. In two thousand six, a female komodo dragon named Flora was living at the Chester Zoo in the UK, and she was at the time one of only two sexually mature female komotos in the whole continent of Europe. As I said, you know, many zoos around the world do these komodo dragon breeding programs to try to help get the numbers back up, and at the time Flora had not been breeding. In fact, she had never even once been kept in an enclosure with

a male. Nevertheless, in two thousand six she produced a clutch of twenty five eggs and eleven seemed viable at first. So what could explain this? I mean, you have to wonder, was there like a male komodo dragon running loose in England, secretly getting into the pins when nobody's watching. And if we do entertain that possibility, we have to name that English komodo dragon. What was his name? Oh, I don't know,

a rogue English komodo dragon. Uh, that'd be Rupert, right, Rupert May or maybe kind of it's kind of a Robin Hood type figure. It could be a Komoto Hood. Robin Koma's not Clive, He's Clive, Okay, So Clive? Did Clive get in there or did something else happen. Turns

out it was not clive. So there was a paper published in Nature in two thousand and six by Watts, Bully, Sanderson, Boardman, CPI, and Gibson called parthenogenesis and Komodo Dragons, and the authors here performed genetic fingerprinting tests on the eggs of these dragons, and they found that in both cases the offspring were what are known as parthenogens, which are made entirely out of their own mother's DNA, rather than through sexual recombination with a mail. And in the case of Flora, this

was true virgin birth. But in both cases they had created baby komodo dragons without the help of a mail. So the author's note that the offspring were homozy guess at all loci on on their genome, but that they were not identical clones of their mothers. So how would that work? Well, you've got to think about what happens in sexual recombination of an animal like this. So the mother contributes half of her genome and the father contributes half of his genome, and they combine to produce a

mix of the two. And in this case the mother still only contributed half of her genome. So in order to produce an entire genome in the offspring without any mail input, the mother's half set of chromosome simply doubled itself. So the offspring are not clones of the mother, their homozygous at all loci. So everywhere you look on their genome, there's a double copy of the same allele, all made from half of the mother's genes. But so, how does this happen? You know, I was wondering, what are the

actual mechanics here? Uh, there's a there's a pretty good summary in a Scientific American article from the time by Philip y am Uh and yam rights quote. Evidently, in the case of these komotos, the doubling of the egg genes occurred when, in essence, another egg, rather than sperm, did the job of fertilization. Oh genesis, the biological process of making an egg cell typically also yields a polar body, a mini ovum of sorts containing a duplicate copy of

egg d NA. Normally, this polar body shrivels up and disappears. In the case of the komodos, though, polar bodies evidently acted as sperm and turned over into embryos. So it's like the eggs cell had a little copy of itself there with it that would normally shrivel up and go away, but instead it pretended it was sperm and then fertilized

its own copy another thing. After producing some offspring parthenogenically, the one Komodo dragon, Sun Guy went on to produce a normal clutch of eggs with a male named Raja. So the researchers also concluded that parthenogenesis is not a fixed reproductive trait that lasts forever. In the Komodo dragons, you can go back and forth. So, in fact, the findings suggests that this is probably probably a form of reproductive plasticity. It's the ability to switch between sexual reproduction

and asexual reproduction when mates are not available. Amazing. Yeah, I mean you can see why this would be a tremendous survival advantage. I mean, in particular, when you have a case where a female is not exposed to males at all for an extended period of time and yet is capable of producing viable eggs. Like if there's no mail around this, this show still has to start one way or another. Yeah, Now there are some reasons you

might think that there are genetic drawbacks to that. In fact, the author is right that there is a downside to this discovery. Quote, parthenogenesis presents a previously unrecognized problem for

the genetic management of threatened populations. Why would this be well, in captive breeding programs designed to help commodo dragons build their numbers back up, females are often kept isolated from males, and males are only brought in occasionally for the obvious reason there are good sense to do it like this, like sometimes these animals are aggressive toward one another, and you don't want them unnecessarily fighting or injuring one another,

that kind of thing. But this means that if you keep females in all female environments with no mates, they may spontaneously give birth to parthenogens. Now what's wrong with that? Why Why wouldn't that just help increase their numbers even more? Well, it doesn't quite work like that. The problem is parthenogenesis

reduces the fitness of the komodo dragon gene pool. The author's right quote oppressing concern with parthenogenesis is instantaneous homozygosity of the entire genome, as this inbreeding carries an associated risk of reduced fitness and an increased probability of extinction. Uh. And then there's another problem with the parthenogenesis, and it's that it biases the sex ratio of the offspring. Uh.

The author's right quote. In Verona species, females have dissimilar chromosomes Z and double you sort of like human chromosomes sex chromosomes X and Y, uh, continuing with their quote. Whereas the combination Z Z produces males, so the parthenogenic mechanism can produce only homozygous ZZ or w W individuals and therefore no females. So the parthenogenesis in the Komodo dragons, because of the way their sex cells work, they can

only make male offspring. Uh. It's sort of the opposite of the way like human sex chromosomes work, that males have an x Y chromosome and females in humans have an x X chromosome. In the dragons, it's the other way around. The males have the same two sex chromosomes and the females have the two different sex chromosomes. If you can only make a duplicate copy, you can only make new male dragons. Yeah, and this is important to keep in mind as we move forward, because we're going

to see, um, you know, the exact chromosome. All situation is going to play into what kind of offspring are produced by a given species density for parthenogenesis. Yes, so back to that question about whether this is uh, this is useful in the wild. It does seem like it's probably an adaptation right for the reason you mentioned earlier. Assume a wild female Kommoto dragon finds herself isolated on an island environment. Maybe she gets washed up somewhere after

a storm. She could help her genes survive by parthenogenetically producing a clutch of males with which to mate and establish a new colony genetically. This is not ideal, but it's better than nothing, But it's not good for the dragon populations that are you know, trying to be sustained right now, for the females to be laying clutches exclusively

of essentially inbred males. This may be better than nothing in the wild when there are no males present, like we said, but it actually interferes with the breeding programs that conservationists are using to help like replenish the species. So this leads to the idea that hey, maybe we should be careful about keeping female dragons in isolation in captivity because when there's no mail around, this can happen and it's not actually what's best for the species if

we can help it. Yeah, that's fascinating because it's easy to just on the surface of things think, yeah, I go way to go. Commoto dragons just reproduce whether there's a mail around or not. But well, it is better than nothing probably. I mean, if there literally is no mail to reproduce with, this makes sense to do. But the problem is in these cases it's not actually that there's no male, it's just there's no mail right now.

And by the way, it does appear that other female Commodo dragons in captivity have shown this same same phenomenon since the initial batch of observations. For example, it was reported in two thousand and eight that healthy male dragons hatched at the Sedgewick County Zoo in Wichita, Kansas from a female who had not made it with a male. But Commodo dragons are certainly not the only reptiles that

exhibit parthenogenesis. Some lizards are even obligate parthenogens that you mentioned earlier, the ones that have no choice, like the hybrid new male Mexico whiptail lizard. Uh, this is an

all female species and there's no sexual reproduction whatsoever. Or well, actually, what is true is that there is no sexual fertilization there uh, because in fact, these lizards have been observed to perform a series of same sex female courtship and mating rituals, the biological function of which is an interesting

subject that we could return to in the future. Uh. And I guess it's just a reminder that even in the animal world, the fact that you don't have to have sexual fertilization doesn't mean that there's not sexual behavior. All right. On that note, we're gonna take a quick break and we come back. We'll get into another reptilian species that exhibits virgin birth. Thank alright, we're back. So we've been talking about komodo dragons. We mentioned lizards reptiles

that exhibit parthenogenesis. Snakes are another great source of examples of parthenogenesis. There is at least one species of snake called Indo tie flops brahminus, also known as the Brahminy blind snake, which appears to be an obligate parthenogen. It's a burrowing blind snake, so you'll find it, you know, down underneath the soil and rotten wood and leaf litter

and stuff like that. It's found naturally in parts of Africa and Asia, though it has been introduced in other places, and as far as we know, all members of this species are female and they reproduce completely without sex. However, plenty of other snake species have been shown to exhibit facultative parthenogenesis, like the Komodo dragons. It appears to be

some kind of adaptation. Now, apparently, for a while this had only been observed in captive snakes that we're living in, you know, in tanks or in zoos or something like that, so it was believed to be some sort of captive syndrome. But more recently it appears that facultative parthenogenesis has been observed in wild snakes, sometimes even when males are present.

Just to cite one example by Booth, Smith, Eskridge, Hass, Mendelssohn, and Shoit, facultative parthenogenesis discovered in wild vertebrates in Biology Letters in two thousand and twelve. These researchers used quote micro satellite DNA genotyping and litter characteristics to determine that there was evidence of facultative parthenergenesis in snakes in the wild in populations of wild North American pit viper snakes

like the copper head and the cotton mouth. So the world may may yet be full of a sexually reproducing copper head queens. Well, that's amazing. Now we've so far we've talked about two different reptile species. It's I think it's time to move on to the birds, and not just any bird, but a bird that we've discussed a fair amount on stuff to blow your mind, especially given that we've never devoted and have we devoted an entire episode to them before? Did we do an episode on

the turkey? No, I think we've mostly talked about turkeys in the context of Benjamin Franklin and electrocuting them. Yes. Yeah, I think that's the main reason they keep coming up, So that's come up more than once. Yeah, Well, we're bringing up turkeys again because parthenogenesis has been observed in several bird species, though it usually results in non viable embryos that never become adults, and the turkey is one of the one of them. Reports of turkeys exhibiting virgin births.

These begin to roll in, especially in the eighteen hundreds, and it received a fair amount of attention in the decades to follow. Breeders were particularly interested because potential pitfalls aside, and we've discussed what those those are regarding, you know, stagnant gene pools and all the idea. They really like the idea of one prize turkey creating another prize turkey

without mightying the genetics horror. Yeah, but you know, we we're talking about the poultry industry here, so the shadowy mechanical priests of poultry science. So according to studies in the seventies and nineties, in particular, thirty two tot of infertile eggs may initiate development, but most embryos die at an early stage. Parthener genesis has also been observed in

domestic hens, Chinese painted quails, and the zebra finch. For the turkey, however, it's only going to result in a viable offspring in extreme situations, and when it does result in an actual hatchling, the turkey is always male due to sex chromo chromosome dominance. Now I was looking around for some more information about this, and I realized, well, the best place to look is probably the world of

of of Agricultural sciences and animal sciences. And indeed I found a wonderful overview of this from Thomas F. Savage, PhD, Professor and head advisor at the Department of Animal Sciences, Oregon State University in Corvallis, and he points out that the parthenogenesis and turkeys, it all comes down to environmental

and genetic factors. So, first of all, the environmental factors that the outlines here age, he says, there's a higher rate in younger hens, and then and then there's also a viral influence here, there's an increased occurrent and turkey hens exposed to certain diseases such as Newcastle disease, foul pox, etcetera. Also,

it can be affected by what you're feeding them. There are certain additives used to enhance reproductive efficiency that can stimulate parthenogenic development, specifically the yeast culture UH sacro mices sera visa. And then also inactivated or I radiated sperm. In experiments, they found that if they if they had this irradiated sperm, it was unable to contribute genetically, but

it could lead to a higher rate of parthenogenesis. Oh, because it could like um stimulate the egg to start dividing, but it wouldn't actually provide genetic material. Yeah, that's my understanding of it. Also, temperature, even elevated pre incubation edge egg storage temperatures can play play a role and in all these you know, and we're talking about increasing the likelihood of it occurring, not necessarily like a trigger switch exactly.

And then their genetic aspects as well. Uh, some genetic strains just have a predisposition for it, and you can actually increase the chances via genetic selection. And this was proved out in a nineteen five study by this guy Olsen, who when you look at he's the turkey parthener genesis. Yeah he is. It's like it's you look at who has done research about it, and it'll be you know, various names and then like like twenty something different search

results for this awesome guy. All right, so that's turkeys and uh and imagined some of you out there listening to this podcast have some experience with turkeys or at least hens um. Maybe you can write in and tell us give us your take. On Parthener genesis in the Turkey world. Now, not to downplay the dangers of turkeys, but I think we should go to a little bit of a wilder territory. Can you give me a thrill ride, Robert. Yeah, let's talk about parthener genesis in sharks. And also we'll

get into raise a little bit. Uh. This is actually I believe this is a topic that that Mara hart Um, who wrote Sex in the Sea, touched on a little bit when she appeared on the program in the past. Uh. And I'm certainly going to cite her book Sex in the c because it is a tremendous book about uh, the wild world of reproduction in in Earth's oceans. But yes, as it happens, sharks have been observed to engage in

facultative parthenogenesis. It's it's not obligatory, and it creates offspring genetically distinct from the mother or sibling species, so these are not outright clones. Uh. This was first observed in sharks back in two thousand seven when Uh, studied by a Chapman at All, conducted tests on bonnet head sharks born in captivity. Um. The female in this Listnari had been isolated for from males for more than three years, and there was so and it turned out that they

were able to produce without any male DNA. Also, in two thousand seven, Chapman and his team found evidence of parthenogenesis in female black tip sharks. These in captivity for nine years without access to males, and a female black tip what happened is it died in captivity with a near term embryo inside it. Zebra sharks and white spotted sharks shark cases have also been confirmed UH and UH. Chapman and his team have also found genetic evidence for

hammerhead virgin birth as well. So the ability seems like it might be pretty common actually, from big sharks to a little sharks, from egg layers to lie birthers. But does it happen in the wild or is it just something that occurs in captivity? This is in this we're encountering a similar situation that we have with the study of commodo dragons, like is this is this something that is actually occurring in the wild, and if so, how

can we study it? It's actually pretty hard to study in the wild, though, because to do so you really need to look at the DNA of of the mother. You need to look at the DNA of the offspring. And the thing about shark uh, the world of shark parents is that they're pretty much donezo after the birth. You know, the the parents are not going to hang

around and look after the baby. Sharks not big into nurturing, right, Yeah. Now, Chapman and other re searchers, they have found examples of parthenogenesis in the critically endangered small tooth sawfish, which is threatened by over fishing and the loss of mangrove habitats. Now it's technically a ray, it's not a shark, but it winds up in shark fin soup a lot. According to mar j Hart in her book Sex and the Sea, this uh, this creature's population has declined, she says, more

than since the nineteen sixties. Now, meanwhile, we have Dr Jim gel Sliter who has conducted test using an ultrasound one which which he described he himself describes as looking like a Ghostbusters proton pack. It's a pretty expensive piece

of equipment. But the but that's how they can bring it out of the field, because it's quite a production they have to go through here, they have to they have to catch the ray, they have to keep invited by the side of the boat, and then they have to uh, you know, use the wand on it to see what's going on inside it. Um. What do they find with that wand? Well, the thing is that they have confirmed parthenogenesis. Uh. Now uh, it's a There are

a couple of things that should know here. One is that investigations regarding sharks and rays they can be complicated for the same reason that like the commodo dragon situation is complicated uh, in that you have to ask yourself, well are they storing sperm from a previous encounter um and And that can sometimes be the case with sharks

and rays um. But in the case of the sawfish, this is an example where this amazing adaptation could prove vital and helping them bounce back from the brink of extinction while new protections are in place, because there at a point now where again they're threatened by by overfishing and habitat loss, but certain legal protections that have been put in place, and so parthenogenesis could be the tool that helps them reach a sustainable level while those protections

are in place. However, over the generations it's you know, likely gonna uh you know, a negatively impact the species hopes for survival as well. So again it's that's that's similar scenario with the komodo dragon. It's better than nothing, but it is also potentially genetically devastating. So the reasons would be what that it limits genetic diversity essentially it's similar to inbreeding, and that it produces sex bias in the offspring. In this case, they would be almost always

female offspring. Yes, I believe so, the I mean think of it, It would just be it would be terrible when your your species bounces back from the brink of of of extermination and you're able to do so via this miraculous virgin birth, but then some sort of disease just wipes all of you out because you lack the genetic diversity to survive it. And this is actually outside

of the world of partheno genesis. This is something that is encountered to in efforts to restore certain species to the wild, Like if a population becomes uh too shallow, then you know you're you're not going to have the genetic diversity to really um have a have has a robust a genetic presence for the species. Yeah, but when you're when you're that low as a species, you're you're in a tough situation anyway. So best of luck to the parthenogens. All right, we want that note. We're gonna

take one more break when we come back. We're gonna ask the question, what about parthenogenesis in mammals than alright, we're back. So we've been discussing parthenogenesis in sharks and reptiles and birds. Uh. One thing that is certainly true is that you're going to find way fewer examples of this in mammals. In fact, if what I've read is correct, there are no known wild examples of parthenogenesis in mammals.

There have been examples that have been induced under synthetic lab conditions, but we've never found an example out in the world that's correct. That's that's what I was finding as well. Um, the really the only uh, the million examples that we run across our ones in human created

uh myths and legends and religious stories. So I was reading an article titled parthenogenesis, Birth of a new lineage or Reproductive accident by Casper J. Vander Koo from the University of Groningen and Tanja Schwander, and this was published in Current Biology in two thousand fifteen. And the authors they make an interesting choice, an entertaining choice in directly approaching the birth of Jesus Christ. Oh yeah, that's a

dangerous move. And Algy I was I was hesitant to incorporate too much Nativity story into this episode, but then the scientists did it, so I can only follow them. In fact, I want to read a quote from this paper. Quote. This reference to parthenogenesis, and by this reference is referring to the Nativity story is unusual in two ways. First, it is the only account of quote unquote natural parthenogenesis

in a mammal. Mammals are believed to be completely unable to report to reproduce via parthenogenesis because of a number of developmental and genetic constraints. Second, while the blessed Virgin Mary might have been able to conceive a daughter via parthenogenesis, the conception of a son is highly unlikely, as male sex and humans is determined by genes on the Y chromosome. Mary, as a woman, could not have transmitted any hy chromosomes

to her offspring. In contrast to humans, parthenogenetic production of sons is expected in species with other types of sex determination. Yeah, so that's dealing with the opposite of the komodo dragons issue we talked about earlier. Right now, I have to say it. I can't help but think of certain late medieval traditions in which Christ is illustrated or described in

terms of feminine qualities. Um. And then this is based in the idea that it's, you know, to an expression of the feminine characteristics of Christ nature, and of course has nothing to do with genetics or even any sort of egalitarian ideal. But yet I can't help but think about that. And when we're thinking about well, uh, yes, Mary could have genetically speaking, had this virgin offspring, but it would have had to have been a female. Now I assume that they are just having a little bit

of fun with the subject. They're not like trying to say, how can we explain the story of Jesus birth. Let's try to go to the science of parthenogenesis. I feel it's kind of like, uh, in the same way that we talked about papers about hemorrhoids. They feel that they just have to mention the the the the ark of the Covenant, just because you can get a little bit of Bible flavoring in there. It's kind of hard to resist incorporating this, the story of the birth of the

Christ Child into your paper on genetics and parthenogenesis. Yes, I can certainly imagine that temptation. But so so they're not actually saying, this story is a historical record and we're going to explain how it happened biologic correct um. So you know, they point out a lot of what we've been talking about already. That male producing parthener genesis is rare, female producing parthenogenesis is widespread and mostly obligate, though only a few examples invertebrates, and there are no

examples among mammals. And then is this whole issue with the female or the or the male offspring? They say that accidental parthenogenesis is the method that can produce male offspring due to the way that the chromosomes come together. But that quote, the developmental and genetic constraints in humans and other mammals would most likely prevent the emergence of adaptive parthenogenesis in natural populations. Well, I do think it's

interesting they say, most likely. I wonder exactly how unlikely, it is, so could parthenogenesis in in mammals like humans? Is that essentially impossible or just so unlikely we wouldn't expect to see it? Well and true? And then also the question is like what kind of time frame we're talking about. Are we talking about tomorrow, our next year or hundred years from now? Are we looking at at at a longer history for our species? Wouldn't expect to

see it over a population of X number? Right, But then again, it's we're going beyond mere humans here, right, we're talking about mammals in general. And so if we have no examples from the mammalian world, uh that that that have presented themselves or have survived to present themselves uh to scientists today, then it does it does make you wonder how many mammals other than humans could there be?

What you've got, dogs, you got rats, Uh, that's about it in there, well, all the all the bat species. So yeah, yeah, yeah, yeah, you have considerable member species to consider here, but yeah, there if none of them are presenting an example of partheno genesis, then um, I don't know, it seems like a pretty safe bed alright. So there you have it, parthenogenesis, virgin birth, a little

bit of holiday full air thrown in there. Uh, And I think just the big take home is that, as always, when we're looking at something that is miraculous to humans, take it out to the animal world, and generally you're gonna find that it's actually no big deal. There's there's much weirder stuff going on, and plenty of if examples of virgin birth going on. Uh, certainly in the invertebrate world, but then also in the verse of your world as well.

It tends to remain the case that no myth, no magical story, no monster movie, no sci fi special can come up with anything as weird as nature. All right, So hey, as always, if you want to check out more episodes of Stuff to Blow your Mind, head out and over to stuff to Blow your Mind dot com. That is our website. That it's where you will find all of the episodes. You'll find links out to our social media accounts. You'll find a tab for our store. We can go check out some cool designs, get him

on stickers, shirts, et cetera. It's a cool way to support the show. And if you want to support the show in a way that doesn't cost you any money. Simply rate and review us wherever you have the power to do so, and hey, check out Invention. Invention is the new podcast that we've launched. If you like stuff to blow your mind, you're gonna love Invention as well.

It publishes every Monday, and in each episode, Joe and I look at a different invention, a different revolution in in uh in technology, where it came from, how it came about, and how it's changed the world forever. You can find that wherever you get your podcasts. If you search for Invention Invention podcasts, you put in our names. You might even might want to throw in something like our names or throwing an iHeart Media, etcetera. iHeart Radio

and see if that helps the search results. But you can also find everything about it at invention pod dot com. Big thanks as always to our excellent audio producers Alex Williams and Torii Harrison. If you would like to get in touch with us directly with feedback on this episode or any other, to let us know a topic you'd like us to cover in the future, or just to say hi, you can email us at blow the Mind at how stuff works dot com for more on this

and thousands of other topics. Is it how stuff works? Dot com Don't Busy pointed to part F