Strange Milk

and fish, they get the backbone going on. Mammals, along with birds, are of course endothermic or warm blooded, which can that can sometimes be a misnomer because, as we've discussed before, there are cases where mammals can cool their bodies down quite a bit. Most mammals, excluding monotreams, have

live berths rather than laying eggs. Mammals generally have hair as opposed to scales or feathers, right, unless they've lost that hair by becoming aquatic creatures or for reasons yet unknown, right, or for living underground, etceter Right, Yeah, yeah, and then we get to the big one, of course, It is that mammals nurse they're young, with milk, and this is

one of the real miracles of nature. It is really, and we're not just We're not just saying that because milk has such an important role in human child rearing, or because humans have this weird thing where we drink the milk of other species, especially around the holidays. You know, this is kind of a slightly holiday themed episode because a lot of people drink eggnog boiled custard type drinks, which are more traditionally milk based. Is eggnog a dairy product.

I thought it was made with eggs. I have no idea. Oh yeah, there's cream in there. I mean, obviously if you can get the soy nog, which I have memories of being tasty, and yet this year I do. Yeah, I have memories. I see like I saw it in the store. I got kind of excited. I got a particular carton of soy nog, brought it back home to share with my son, Um who is Um Who's who's six and uh and he said, oh, this is good. This tastes like wet cold sugar. And I was like, yeah,

it does kind of taste like wet cold sugar. It doesn't have this particular I don't want to damn all soy nog because I have to be remembering something real. But this particular one, yeah, did not have that fatty, creamy, uh finish to it anything, but like normal full fat milk products always does have a kind of strange sweetness to it. You're noticed the odd sweetness of skim milk. There's something feels a little off about it. Yeah, I mean it's been a while since I've had skim milk.

I do tend to just use um, like soy milk, almond milk, coconut milk, that kind of thing these days. Um, And thus my desire to get in the Christmas spirit by buying soy nog. Right, But so okay, it's not just the role in human culture that we use the milk of other animals in our cuisine, which is pretty much objectively weird. I think that's one of those things aliens would come to Earth and see us doing and think was weird. But it's also that it's it's a

deep part of what we are as an animal. The possession of memory glands and the rearing of children with milk is uh that that's like a main morphological feature of what it means to be a mammal. The word mammal basically means like breast beast. Yeah, we are a bunch of breastbeasts really so yes, it nourishes our offspring and in doing so helps to establish immune system competence

as well. Now, the exact nutrient composition of milk is going to vary across a lot across species, and it also can change quite a bit depending on the different stages of lactation, which is something that's easy to overlook. Milk is not just necessarily oh, here's the here's the formula coming out, and know the formula will change. The actual nutrient load will will vary depending on the developmental stage of the young, So milk fat content and seals,

for instance, can be as high as six. Meanwhile, it's basically nothing in wallabies. And speaking of wallabies, according to the Origin and Evolution of Lactation by Capuoso and Acres Posting two thousand nine, quote milk in the tamer wallaby that's uh. Macropus eugeny changes from a very dilute secretion containing primarily carbohydrate during early lactation to a more energy dense milk that contains substantial quantities of protein and fat

during late phases of that left lactation. So that's a nice example of just how the the the the exact details of the milk will change during the course of the the young's growth. Now, we could probably devote a whole episode or multiple episodes in the future to the study of milk, true biological mammal milk, because that's a fascinating subject on its own, But today we wanted to focus on something even weirder, which is all of the

non mammal quote milk that's out there. There has been an astonishing amount of research that I had not kept up with until diving into it recently about all about animals you would just never expect to produce milk, producing something like milk, Yeah, I have to say this also forced me to learn about a couple of different creatures I was not familiar with then we brought to my attention solely because they produced something that one might call milk.

So this will be our anomalous milk episode. But before we get into the anomalous milk, I guess it's worth a quick look at actual mammal milk itself. Right now, I know You've done some episodes on dairy products and on mammal milk in the past, right, Yeah, there's there's an older episode that I did with Julie Douglas back in the day, and then more recently did an episode

with Christians Say titled Uh Holy Butter. As the name implies, it's mostly about butter and how we make butter and some of the uses we have for better Did you all talk about bog butter? Yes, we did talk about bog butter. Bog butter is so good. Yeah, but we also talked about how butter and also milk, is nothing short of solar energy transformed through a few different steps into a food. For instance, there's the of course, the

the alchemy of photosynthesis to kick things off. The grass in the field converts energy in the form of sunlight into chemical energy in the form of sugars and other carbohydrates. This is essentially the first miracle of milk. And then you have a female ruminant in this case cow, sheet, camel, water, buffalo, goats,

et cetera. They consume that grass and truly, as Elaine Cosa Rova explores in her tremendous book, Butter a rich history Um, you're better off thinking of it as a processed harvesting rather than a meal, because ruminants are built to transform grass into milk. Uh. Consider that they have these three or four chambered stomachs. Uh. They're upper dental pad instead of teeth from massive for massicating green. And each animal puts its own particular chemical spin on the

process as well. But they crunch up the greens and they ferment them in their mini chambered guts eight hours feeding, eight hours ruminating, and then the remains of the day resting, so that that masceration, the repeated chewing of the cud helps to carry out the second miracle of milk, the transformation of a low fat diet of grass into high fat milk. Yeah. You always wonder about that, right, Like you look at the beginning product in the end product,

and you're like, I don't understand exactly what's happening here. Yeah, And and part of this is just the miracle digestion. The broken down food is assaulted by microbes and the oxygen free fermentation chamber of the gut, the grassy meal is broken down to the basic elements, strings of carbon and hydrogen molecules, and then other backed here recombine the elements into volat how fatty acids. Only half the fat comes from the cow's diet. The rest comes from the

cow's own body fat. Oh wow. Yeah, And so it's sort of it's not just making a product out of what it just eight, but it's giving of itself when it creates milk. And I think that's one of the reasons, like we put the human layer on milk to write like milk is this this giving of something something to uh to to bring nourishment to another. And of course we have so many metaphors related to that, including of course that the milk of human kindness. But in this

example talking just about ruminate milk. Um, it's a you know, fatty liquid to ensure the survival of the animals young and um. The exact composition again is going to vary from species to feat species, with additional factors depending on environment and diet. For instance, uh a new produces twice the fat content of cow milk, Goat milk has smaller, more digestible fat molecules, yak milk has less sugar and more protein, and camel's milk has three times as much

vitamin C water. Buffalo milk has twice the fat of cow milk. And then we have things that are not even um, you know, we don't traditionally think of as milk producers. But consider the whales. Oh yeah, blue whales for instance. Uh this, this always blows my mind. Uh. A newborn blue whale gainst. Two hundred pounds a day just by nursing, and the average whale produces forty times

more milk than a cow. And this has even led some scientists to consider the possibility of milking whales and specially prepared milking bays and then using that milk for human consumption. Is there really any milk of any animal that has not been considered for human consumption? UM? I don't know. I mean there's some that are certainly more attractive. Um. But anytime you start reading around about different milks, I feel like there's a good chance somebody's tasted it and

they will tell you what the flavor profile is. What does rat milk taste like? What what does monkey milk pair with? I don't know. I have sometimes think about cat milk, like, what like tiger milk would taste like? Would it be did you know or who did have kind of a like a meati consistency to it, probably like a nice French washed rind cat milk cheese. I also, this is a topic that I discussed in that past

episode with the the jew. It was of course the the the idea that you do have certain situations that can cause males to lactaatee as well. Uh, some do to some are more like behavioral environmental, and others have to do with their regularities in the body. But you also have certain male fruit bats that lactated, and these are the only examples of male mammals lactating as a part

of a regular parental activity. Yeah, and you can see already in the idea of male animal lactation that there is going to be They're gonna be some like asterisks next to the official like dictionary definition of milk, which is something like an opaque white fluid that's rich and fat and protein that's secreted by female mammals for the nourishment of their young. So obviously there's not that's not quite all cases, because in some cases males secrete it

like the bats you're just talking about. And then I guess the question comes in where if you have something that meets all those qualifications but is not produced by a mammal. Is that technically milk or not? I think a lot of biologists might say no, but they might still use the term in describing whatever this other substance is. What is the substance on the Simpsons that they're drinking in the school cafeteria. I think it's rat milk now with vitamin R. Oh, my bones they feel so brittle.

But I always drink plenty of malk. Well, maybe it's mack, maybe it's milk. Well, whatever you call it, milk, malk, milk analog. There are clearly strong reasons that non mammalian animals would would have an incentive to secrete milk like fluids that they used to feed their young. It's a really useful strategy and it serves quite a few dif functions. I mean, for one thing, it allows the parent to produce food for their offspring without having to like leave

or hunt or forage. You don't have to go out of the nest. Another thing is that it tightly controls the nutritional content of the offsprings food, making sure they get exactly what they need. And you can see that in the very different nutritional profiles of milk, like you were talking about earlier, like with wallabies and stuff. It's also a way for the young to eat all the mother without actually eating the mother. Yes, exactly, Uh yeah,

and so it can. It can include extra nutrition, lots of fat and protein, maybe more fat and protein than you could expect to get from food sources in the environment. It's like super concentrating the nutrition profile for the young, which will help them speed up and grow faster. And then it can also deliver really important additives. Earlier you mentioned immune function, and that does seem to be a

very important role of of milk and animals. The idea of stimulating the immune system with antibodies or supplementing the offsprings microbiome with microbiodelic commenceled bacteria from the mother. Yeah, I feel like this should come as no surprise following our poop eating eating animals episode, because obviously, if if eating a little um parental poop is going to provide that kind of a boost, obviously that kind of boost

might be available via milk. And then on top of all that, like the additives for the immune system, you also can add hormones. This can be especially useful when it's like hormones that could have something to do with cementing the psychological bond between parent and child, or things like growth hormone to help speed up the growth of the young. So with some of that in mind, it might be less surprising what I'm about to say, which is that a number of bird species secrete a substance

analogous to milk. I think we should look at a few, Robert, will you look at milk birds with me? Let's do it. How about pigeons. Pigeons both male and female, regurgitate a highly nutritious substance known as crop milk into the mouths of their young, and don't let the fact that it is delivered in the form of nourishing barf throw you off. This is not regurgitated food. This is not the parent bird providing a partially digested version of what they just date.

Crop milk is a separate, original substance secreted in the crop organ. It's from the parent's body itself. Now the crop organ is I don't know if you've ever seen one of these, ROBBERTI, it's sort of have not. It's like a pouch area in the esophagus that can be used to store and moisten food before it continues on

down the elementary tract for digestion. And I think it's thought that um the crop organ is useful for like prey species of birds that might be trying to gobble up a bunch of food really fast while they're out somewhere exposed and then be able to fly off quickly and reduce the amount of time they're out there eating

and exposed to predators. So you want to be able to just like stuff it all in, like get it all down there really fast, and then get out of there, and then you can settle down somewhere safe and try to digest. It's a it's a it's a doggy bag essentially inside the body, Yes, exactly, it's it's your it's your styrofoam clam shell inside the bird's throat, and so the crop milk, it's actually produced by pigeons and doves.

This is described in a paper I'll come back to in a minute as quote an oily, yellowish cheese like substance that is formed into small seed sized rice shaped pellets. I've also seen it described as cottage cheese but yellow. Well, this sounds fine. I have no objection to any of that. Okay. So apparently crop milk is produced by the inner cells of the crop pouch becoming moist and then sort of

sloughing off into the pouch and then getting regurgitated. So it's like, here's some let me barf you up some of my highly nutritious inside skin. This is my flesh, et cetera. Right now. An interesting thing in birds and pigeons is that this process in parent pigeons is apparently controlled by the hormone prolactin, which is also what stimulates milk production in mammals. That's kind of interesting because you know,

they don't have memory glands. It's not you would think that it would be something completely different, but it's pro lactin in both cases that gets the parent doing this. Crop milk tends to be mostly protein and fat, about six protein maybe thirty something percent fat, and then just a little bit of carbohydrates and minerals and other things in there. A two thousand twelve study in Plos One by Megan Gillespie at All found that if you took baby chickens and fed them crop milk from pigeons. They

sort of became like little minor hulk chickens. After just seven days, the pigeon milk chickens were more than twelve percent heavier than control chickens. And also they showed greater diversity of gut bacterious specifically in the seaka um, and they had higher expression of the immunoglobulin I g A, which is an antibody class that's crucial for all kinds of immune system function. Now, a side question you might be wondering is why did they test this on chickens

rather than on pigeons. I think the answer is that with pigeons you couldn't really have a control group because young pigeons would just die without the crop milk. And there I've read that there have been other studies that looked into this. They're like fed pigeon crop milk two chickens to see what happened, and the chickens always really beefed up. It. It's like it's clearly something that their

bodies respond well to. But there are some other birds that also produce UH and feed their young with secretions from the upper digestive tract that are crop milk or something like it. Flamingos would be an example. According I was reading about the flamingo crop milk feeding on the San Diego Zoo website. They were talking about their flamingos. Oh yeah, they have a great website, great outreach. Yeah, exactly,

And so the a few things they mentioned. One is that apparently when young chicks flamingo chicks are hungry and they're calling out for feeding, it's not just their own parents. Other adults in the flock can be stimulated to act as sort of foster feeders, which is sweet, that's cool. And the way that seems to work is that they they suppose that hearing the sound of the hungry chicks calling for food stimulates the production of the milk like analog.

And then also one of the things they say is that as the parent flamingos produce crop milk to feed their chicks, their feathers tend to be drained of color over time. So like if you've got an adult that's producing crop milk feeding a young one, it turns from pink to a pale pink or even to a white. And then after the they stopped producing it, they gradually get their color back. One more, of course, is emperor penguins.

You may have heard about this, like, you know, the male emperor penguins guarding the the egg while the female goes off to feed. So that goes on. But what happens if the the young penguin hatches from the egg before the female returns from feeding with fish to regurgitate for it. Apparently the male penguin will do something like this, will generate some upper digestive tract milk to bar out for the little penguin, and the little penguin gets its

nourishment that way. So again, it's it's certainly not milk, but it does seem to be meeting some of the criteria we've discussed. Well, it's a lot like milk nutritionally, it seems to serve a lot of the same functions and be composed in a pretty similar way. So I don't know, I don't know whether you should call it milk or not. I mean, again, I think if we go by the technical definition, milk is only produced by mammals, So it's not milk, but it looks like milk, It

apparently tastes like milk, it does what milk does. Yeah, we could call it bird milk or or bird nog a holiday twist. That's good. Well, how about let let me take you to the next step. This one might seem unbelievable, but maybe just a tiny bit less. So, given that birds produce milk like secretions, what about dinohnog?

So what are birds? They are the dinosaurs that survived the fifth extinction right there, the descendants of these feathered dinosaurs that survived when the thing that killed all the other dinosaurs. Now, given that modern birds exhibit a form of what might be considered lactation, is it possible that some dinosaurs also fed their young with milk like secretions.

We don't know the answer to this, but exactly this question is explored by the Australian molecular biologist Paul Else in a Journal of Experimental Biology paper called Dinosaur Lactation. It's like Chariots of the Gods. You know, if you end it with a question mark, you're always safe. It's not in all caps, though, I will say that that is a good point, but no, that this is a

fun question. So he says, you know, if dinosaurs did perform something analogous to lactation, we don't know, but if they did, it's another one of the many soft tissue based biological features that are just going to be extremely difficult to infer from postilized remains. The bones don't usually tell us things like that, So the only way to try to answer this kind of question is to look at the indirect evidence. And so he's got a few

thoughts here. One of them is about the initial size difference between adults and hatchlings of some dinosaur species, especially the sauropods. Yeah, yeah, so he says, like, you know, it almost seems as if it would present mechanical problems and feeding. He said to I believe this was to

a campus newspaper. He was speaking about his paper to quote, although I work at the molecular level, I'm basically a comparative physiologist, and one thing that always struck me as unresolved about dinosaurs was how a dinosaur parent of several tons could feed young of only a few kilograms. It seemed obvious a form of lactation similar to that present

in birds. And then in his paper he writes, quote lactation might free large parents from having to feed their newly hatched young the regurgitated products of their own meals that might be unsued did for altricial young based on digestive systems unfamiliar with coarse fodder like you know, rough plant matter that adults would be eating, and essential nutrient requirements to promote rapid growth, and replace this with secret

secretory products. Oh, that's a hard word. Secretary uh synthesized by the four gut that are more suited to supporting rapid development. So again there's obviously some kind of incentive there would be if they could produce something like this. We don't know if they could, and so if we entertain that possibility for a second, the dinosaurs produced milk for their young, it's likely they did it in the

same way as birds rather than like mammals do. So that would probably mean nutrient rich secretions from the upper digestive tract that would be barfed up into little the little dinosaurs mouths, and paleontologists have discovered evidence that many

dinosaur hatchlings grew very quickly. We do seem to have evidence for that closer to the growth rate of birds and mammals than of reptiles, and a nutrient rich parental secret shin especially if it contained these helpful bioadditives like antibodies and growth hormone, as it does in the case of some birds, could help explain this rapid growth, But unfortunately,

there's currently no direct evidence for dinosaur milk. Maybe in the future some paleontologists will come up with a with a clever way of proving that dinosaurs made crop milk. That would be awesome. Yeah, maybe, I mean that's if we ever get Jurassic Park. That's one of the things that we can also achieve a chance to sample all the various dinosaur milks. I wonder which which one would you prefer if you had to have some dinosaur nog which species? Oh, I'd probably want to go with a

herbivore milk. I don't know if i'd want to try out a carnivorous dinosaur milk. I think I could probably go for what pisar Lofus. I feel like that it looks like a good milk dina. How about packy cephalosaurus.

Oh yeah, the big cranial head butters right, yeah, I think yeah, those are those are those are good good choices that themselves to certain branding, you know, like one is kind of like the brain milk, uh you know, you really want to, you know, smack craniums with with your your your coworker as well, and then you need a you need a bone up on this stuff about try saranogue. Try saranogue is good. Yeah, we'll come back to it. This is what I'm going to keep my

eye on for years. I'm always going to have it in the back of my mind, waiting for that paper that says dinosaurs did have crop organs, they produced milk. All right, should we take a quick break, Let's do it, Thank you, Thank alright, we're back. We're talking about strange milk,

milk like substances produced by non mamalion creatures. Now, remember in the episode we did about amphibians with special guest Markman Decau, he was discussing these amazing creatures called Sicilians, not the people from Sicily, but it is spelled c A E C I L I A N. Sicilians are amphibians like frogs and salam anders, but unlike frogs and salamanders, sicilians are completely without legs. Most Sicilians live underground, so we rarely see them, and if you do see one,

you might mistake it for a huge worm. They kind of look like moist, greasy snakes, So they're sounding more and more like just like an awesome candidate for milk like substance production. Right, So can you milk a Sicilian? Uh? Not exactly, but they do provide their young with nourishing

secretions that are sort of milk analogs. There was a paper by Alexander cup For a bunch of other authors Alexander cup for at All, published in Nature in two thousand six called parental investment by skin feeding in a Sicilian Amphibian. The short version of this is that after the mother of a Sicilian species called boulanger Ulia titanus, after she gives birth, she transforms the outer layer of her skin into a nutrient rich meal for her young

offsp ring. And then the young developed quote a specialized dentition which they used to peel and eat the outer layer of their mother's modified skin. So basically, mom turns her skin into cheese, and these juvenile worm like creatures develop special baby teeth that are designed specifically for eating mom's milk skin. What I love about this example is that not only is it kind of delightfully grotesque and again weirder than anything we could dream up for our

horror movies. Uh. It also, even though it's not milk, it is a milk like behavior. It forces you to re evaluate what milk is as a mammalion feature. Yeah, well, are are you saying that even among mammals we should think about it more like this parent is just ripping off part of their body to give to their young. Yeah. I think so. But you know, I I have it.

I have heard mothers, nursing mothers like speak of it in this in this way, you know where they are, and I would love to hear from from from anyone out there has had this experience where they're where they're like, this is so bizarre, Like I'm all, I'm basically turning my body into this substance and feeding this little larval

human creature. You know, it's I have frequently heard mothers speak about the weirdness of the whole scenario, but I feel like it is a weird There's something about milk that for the rest of the time and for many of us, we just take it for granted. Yeah, it's amazing. We we forget to appreciate the weirdness of reality in so many ways. But this is another one of them. It's crazy, it's amazing, it's around us every day. It's a whole aisle at the grocery store, and it's a

crucial part of human life. Uh and yeah, when you just stop and appreciate the biological realities of it, it is startling. Oh. But one thing I wanted to address about the Sicilians here, so I want to already quote from the abstract uh So quote. This new form of parental care provides a plausible intermediate stage and the evolution of viviparity, which is live birth in Sicilians at independence offspring of viviparous and oviparous which means egg laying dermato trophic,

which means skin eating. Sicilians are relatively large despite being provided with relatively little yolk. The specialized dentition of skin feeding or dermato vegas uh. Sicilians may constitute a pre adaptation to the fetal feeding on the oviduct lining of viviparous sicilians. So there's a lot of Latin words, but in other words, the eggs have the advantage of containing a yolk that the young can feed on. And of course this is why egg yolks are delicious, it's everything

a growing body needs. And live birth instead has the young development feed inside the mother until they're viable to move around and survive on their own. Species who is young have this intermediate stage where eating their mother's butter skin as a yolk substitute or a supplement could be a could be an evolutionary stepping stone between these two lines of birth. Yeah. So that then also this connection between what yolk essentially is and what milk essentially is.

It's like the the offspring is spat out. It's like whoa, mom, there wasn't enough yolk there. Uh, oh, don't worry. I have something that is like yolk that I will now produce for you to consume. It is very much like yolk, and again both both are involved in egg knock. So connection. Think about the nutritional parallels between egg yolks and milk. They tend to be high and protein high and fat

good for growing young bodies. Guess, both useful and making like a a frothy mixed drink like like a ramos gin fizz or something. Wait does that egg yolk or egg white? Uh? That is usually just the egg um egg whitey, though you know, there are other drinks that call for the egg yolk as well. I haven't experimented with as many of those. And of course there are put plenty of drinks that also call for for milk.

I mean egg knock is a great example of that, because that is tipped that is often paired with some sort of a liquor. What's that drink called where you just have a beer and you crack an egg in it? Oh, I don't know, is that like they drink it on the wire? I think I don't remember the name of that one, like the Dockworkers Breakfast, the Champions or something. Never tried it? All right, Robert, have you have you

got some strange milk for us? Yeah? So you know, we're talking about birds, it only, you know, makes sense that we would also turn to the world of fish. Okay, So in particular, we're talking about the discus fish, which is an Amazonian chick lit species. It's a rather unique fish because both mother and father provide sustenance for their hatchlings via mucous secretions. And of course this isn't simply a matter of hatchlings like nipping some mucus from their

parents and then swimming off. This can go on for a month or so. Oh wow, so it's prolonged. Yeah, yea. So it's worth remembering that with the with a fish slime and mucus or or mucus that they're very important. It's not merely the stuff that's on their scales, but it constitutes a protective outer layer of their bodies and

it provides a number of key benefits. UM. One of the big ones that's going to be important here is UH osmo regulation or gas transport, and this is to maintain the internal external osmotic balance UM also sometimes referred to you know, dermal respiration UH. In addition to this, the mucus or slime provides external protection. It can reduce turbulence, and there are other varieties of fish that also use it as a toxin rich outer coating, so it can

be protective. Even if it doesn't have toxins in it, it can provide some level of protection. You have other particularly slimy fish like the hag fish that use it to their advantage. UH. It can also mucus also conserve for water cleansing purposes. It can also form It can also serve a purpose in the cocoon formation in the case of the African lungfish, and some fish also eat their own mucus. So a two thousand ten study looked

into this. It was titled Biparental mucus feeding a Unique Example of Parent Care in an Amazonian chicklet by Buckley at All, published in the Journal of Experimental Biology. So basically they broke down not only the nutrient and immunity load of the mucus, but also how it all changed depending on the developmental level of the offspring, very much in line with the milk production of mammals as we discussed earlier. You know, again, remember how milk changes to

meet the growing offsprings needs. The authors pointed out that like the peak level of mucus, antibody up provision was seen as offspring reached the free swimming stage, and this suggested, you know, a role that's very much like what is provided by mammals. Again, so that you know that there's

a winging off here. Um. You know. They pointed out that the protein was lowest during the second and third weeks of free swimming during a weaning period, and the authors point out that all of this is far more in line with mammalion and avi and parental care than anything we see in in other fish. So it's a it's a rather curious example of you know, it's not milk, it's it's it's a little more like the Sicilian example. And then we're dealing with an out a layer of

the creature's skin. Um, but but still it's it's providing sustenance for the young, and doing so again not in just an off head man or like the hatchlings are out and then they just you know, grab a bite and run off. It seems like we're steadily progressing further and further from mammals, Like we went to birds and dinosaurs, and we went to amphibians, and then we went to fish,

which are still vertebrates. How much further could we get? Yeah, because it's one of those things where if you just came up to somebody in the street and just surprised him and said, hey, have you ever tried bird milk? They might be like, oh, I don't know. It might take them just a few seconds to be like, hey, wait a second. Only mammals produced milk. But when you start talking about fish milk, and and you know, little or insect milk. I think most people aren't gonna buy

it for a second. They're they're gonna say, you're a crazy person. Stop talking about things that don't exist. Let me talk about things that do exist. Robert, go on a mental journey with me. Imagine you are sitting on a park bench in a park somewhere in southern China, and you feel a tickle on your forearm. You look down. There's an ant crawling on you. It has a shiny, segmented black body with antennae wiggling in the breeze. But then you look closer, those aren't antenna They're not coming

out of the top of its head. They're coming out of the thorax under the head, or the cephalothorax their legs, which means this animal has not six, but eight legs. This is not an ant. It is a spider. It's a spider in disguise. This is the spider Toxas Magnus. I've included a picture for you to look at here, Robert, and I like the way, even in this close up, the shiny black body is like catching a fluorescent light on the ceiling that you can see very clearly. Yeah,

and it looks very much like an ant. At first glance, you would just assume this is an aunt. You really have to stare at it for a second to to make out all the legs. Yeah. So it's about a centimeter long, Toxais magnus and it's a member of the family selticitay the jumping spiders. Magnus is also known as the black ant mimicking jumper which needs to catch your name and uh. It's found mostly in Southeast Asia. Now, there are hundreds of species of spider that are professional

ant mimics like this. They're known as the Mermaica morphs and not. They not only look like ants, but they often mimic the behaviors and movement patterns of ants, even lifting and waving their front legs around to make them look like antennae, or walking on people, or walking in patterns that copy the locomotion of foraging ants. And you can imagine several recent spiders might want to look like ants.

Uh that the main pressure actually driving this evolutionary path seems to be the avoidance of certain egg sac parasites like spider wasps and predators like antises and other larger jumping spiders which kill spiders but usually leave ants alone.

That makes sense, right, I mean, because of course, obviously you know all these species that have evolved to prey upon spiders, but associating yourself with the ants, it's kind of, ah, that's a safer bet because the ants have strengthened numbers and they're not the solitary prey that a spider would be, right, or they might just not be nutritious to eat or something. I mean, there might be all kinds of reasons that a predator doesn't really want to go mess with an aunt.

So just a few weeks ago, a group of researchers, mostly based in China, led by a researcher named John chi Chen, published a study in the journal Science revealing something amazing about these ant mimic spiders. It started with the observation that after the young Magnus spiders hatch from their eggs, they sort of became, uh like what you might call indoor children. Instead of leaving the nest, they hung around for a long time time, roughly twenty days.

And then it gets weirder because not only did they not leave the nest to forage, the mother spider didn't leave the nest to forage either, so it couldn't have been going out to get food to bring back to them. Nobody left home or even went out to the grocery store for almost three weeks, and if you know something about spiders, you'll probably recognize that there's something odd going

on here. Like there are some social species of arachnid, but this shouldn't be one of the Most spiders, including generally salt aids. The jumping spiders are aggressive and even even cannibalistic toward one another, so they don't nest together like this except for those those small number of social species. What's weirder During this period of family time, the young spiders grew a lot. If they were growing, they had to be eating, so what were they eating If nobody

ever left the nest. You can probably guess where we're going with this. The authors started watching more closely just what was happening in the nest, and what they found was strange and fascinating. During the first week after hatching, the mother spider would secrete droplets of an unknown white milk like fluid from a ridge on her underbelly called the epigastric furrow. This is also where the spiders eggs

are produced. Interestingly and uh so, after she secreted this fluid, she would leave droplets of it on the walls of the nest for her offspring to eat, and after the first week, the young spiders would just climb right up on her and drink the secretions directly from the mother Magnus's epigastric furrow. So this milk substance feeding took place for the first forty days of the young spiders lives. Even after the young spiders finally started leaving the nest

to hunt, they would come back. They would come back to the nest and supplement their insect diet by getting more spider milk from the mother. That's incredible. Yeah, So the researchers also found that when the spiders were unable to feed their young with this spider milk, all the young spiders died thin less than two weeks. So it's not just a little something extra, it's necessary for the life cycle of the species. And the spider milk they

found is incredibly nutritious. They found that per mill leader it contained two milligrams of sugar, five point two milligrams of fat, and a hundred and twenty four milligrams of protein, which is a lot that's expressed as four times the protein content of cow's milk. And of course I envisioned an awesome future whenever we finally chuck it in and just start hawking bogus nutrition supplements to bodybuilders, We're going to do the spider milk protein bomb stack. I love this.

I really want to incorporate this into Dungeons and Dragons because you have various species, particularly in an under dark um, the vast subterranean realm in the setting that depends on spiders. The gray dwarf of the Dugard. They have these kind of like a pack pony spiders that they use, so it makes sense that they would be drinking some sort of spider milk. And now there's a there's a scientific

reason to incorporate that into everyone's campaigns. Doesn't science always end up proving the D and D monster manual correct. One of the co authors on this paper, Richard T. Courtlet, says, quote, our findings suggests that lactation may arise in non mammals when it provides a significant advantage in offspring survival. Well, as we've been seeing from the other examples in this episode that's clearly true. Uh. He also says that it's useful in this species because of the small size of

the hatchlings. They're tiny and unable to hunt, or at least initially unable to hunt or defend themselves from predators. But ultimately the researchers don't know why this strange mammal like trade has evolved in this one species of spider. As far as we know, at least so far, this is the only spider that does this, and it's very weird. And another thing that was pointed out that was pretty weird is that the mother magnus didn't just offer her

milk to the young. She also displays like social parenting behaviors, like maintaining a clean and safe nest environment for the young to hang out in. Just kind of kind of weird for spiders. All Right, on that note, we're going to take another break, and when we come back, you know, we'll we'll keep having some arachneid milk. Thank Alright, we're back, Robert.

Are you going to feed me with the milk of arachneids? Yes? Yes, we have another another arachneid species here that's producing something that's kind of like milk. So we're talking about the pseudo scorpion. Nice. Now, the pseudo scorpion really sounds like something that your hey, Luis Borees would have just made up. It's a tiny arachneid that can frequently be found living in old books, protecting them from decay by feasting on book lice that munch on the starch based book binding glue.

That is that is good? Yeah, I mean it really does sound like something that Borees would have made up, like, oh, well, the the old books are home to these tiny creatures and they eat other tiny creatures that they want to destroy the books. I don't know it did, There's there's something beautiful about it. Yeah, it's like something that would have been imagined in the marginal illustrations in one of

the scripts in the Name of the Rows. Yes, yes, and and and they do literally live in the margins, so it makes sense. But if you see them, they look kind of like scorpions without tails, like they got claws. Yea. They're sometimes called false scorpions because they are in fact not scorpions despite having these big pinchers. They have some

really impressive looking pinchers. And there are some thirty three hundred species of false scorpion that live around the world, but the most famous is callith can crow Eades, which can reach four millimeters in length. So I was reading

about this. The author bet Crew has a wonderful post about them on the Scientific American blog titled how book scorpions Tend to Your Dusty Tones, and she discusses, among other things, they're they're dancing and rubbing mating rituals, which sound quite cute, but then it gets really kind of weird and brutal. Quote he dumps a sack full of sperm on the round, and it gets worse because then he pushes the female down into his sack full of sperm on the ground. This whole process can take anywhere

from ten minutes to a whole hour. The sack full of sperm will be taken in by the female's genital orifice and she'll end up producing twenty to forty eggs, which she'll carry around in her abdomen even after they've hatched. Well that's weird sex, yes, yeah, so everything gets a little less borhe than a little more. I don't know, geeker, I guess, but but here's where we get to the

sweet book scorpion milk. So the larvae will hang around and the young, the young book scorpions will even hang out around on her back until they're old enough to go off on their own. But as larvae, they remain inside for a while, living in her genital orifice and feeding on a milk like substance that secretes from her ovaries.

So they feast on this stuff, and eventually she's just so emaciated from the consumption, uh, that the tiny book scorpions just have to leave, like they can no longer hang out in the orifice because there's just not enough book scorpion milk to go around anymore. Ungrateful, Well, you know, she does, She does a lot, She does what she can, and then they have to move on and eat some book lice. Somebody out of whip some independence into those.

Maybe book scorpions getta eating book lice earlier. Now I have another couple of creatures to mention here. These are insects, but they also illustrate what's going on. So bat flies. I was not familiar with bat flies, but they are fascinating little creatures. They are as the name implies, parasites that feed on bats. They do, not, however, look much like a traditional fly whatever you're imagining when I say bat fly, it ain't that. Are we going to try

to say? The family name of the bat flies? Is it nick ter Ribida? Yes? I think that would be my guess, nick to Ribidae. Uh. They are wingless, spider like insects with long legs and a small head that folds back into a groove in the thorax when it rests. So earlier we had a spider that kind of looks like an insect. Here we have an insect that kind

of looks like a spider. They also have a highly developed uterus and milk glands there, or at least they were referred to as milk glands milk in quotation marks here. And these glands seem to play a key role in imparting important bacterial indo symbians to the offspring and other insects engage in this kind of behavior as well, as they host bacteria in their cells that provide important boosts that food alone cannot give them. These indo symbians are essential.

For example, the tetse fly hosts a bacterium that provides b items that are not available in uh in the flies normal diet of blood. Isn't it amazing? How Like we think that animals rule the world, but like almost all animals are just so dependent on invisible microbes in order to even just get the basic nutrition they need out of their food. Yeah, it's it's crazy, it's crazy. But yeah, again, this is a great example all of

just like, it's almost like a simple model of milk. Hey, baby, you're just gonna only eat blood, but there are things you need. I will have to provide them through some handy secretions. Well, there's another insects secretion. I want to talk about. What kind of yummy milk do you have for us? Now? It's cockroach milk. So you're not a fan of cockroaches, are you? How do you know anyone who is? Oh, I'm sure there are lots of people

who love cockroach. I mean, he'sing cockroaches are kind of I think cockroaches are only interesting if they are exotic or their pets. Nobody wants just free range cockroaches or palmetta bugs. Is you know we regionally call the larger ones that invade our homes. Nobody wants those around though, like that. We have just an inescapable around here, inescapable, and I feel like we have instant kill instinct with them.

No matter how much you have to you have to be pretty hardycore animal lover to say, oh, the Palmetta bug is here, let me attend to its needs. And smashing one of those Georgia cockroaches is basic, really like smashing like a three foot wide jellyfish, Like it leaves this explosion of of mucus and liquid everywhere. They are so big and so juicy. Yeah, and they'll they like to hang out I've noticed sometimes tauntingly on white walls. We're like, oh, I can't squish you there, because there

will be a The mark will haunt me forever. You ever walk into the bathroom in the middle of the night, turn the light on and there's a cockroach on your toothbrush. No I haven't, I haven't. It's happened to me. I have not encountered that, But now I have that that image of man, and now I will fear it. I do frequently, never know, I do frequently notice how you'll I'll go into a room. It might be the you know, the kitchen or wherever, and you turn on the light

and it's not. You don't always necessarily see the roach all at once, but suddenly something clicks in your mind, like there's something something is off, like you know, and then you have to look for it, and then you find it, you know. But we we say we have like a high level of awareness for them. So there is a species of cockroach found in Asia and in the Pacific Islands. I think it's found a lot in Hawaii, known as the Pacific beetle cockroach or diploped Tera punk tata.

And there are several interesting things about the species of cockroach. First of all, they are the only known truly viviparous cockroach, the only cockroach we know of that has real live birth instead of laying eggs. Second, this kind of interesting. They do chemical warfare. They produce an organic compound that's known as quine owns from specialized tracheal glands, and this is probably a chemical weapon they use against predators. There are analogies for this, like quine owns are used as

part of the chemical defense of the Bombardier beetle. And then finally, researchers have discovered that this cockroach who gives live birth to its young also secretes a type of protein rich, light yellow milk like liquid from her brew sack, and then the young ones drink it. Okay, tell me more about this roach not well. One of the one of the researchers who first discovered this was the University of Iowa emeritus biologist and insects surgeon, Dr. Barbara Stay,

insects surgeon. How do you become an insect surgeon? That sounds like an awesome job, very delicate hands. Yes, you've gotta be like so many steps above, like the human neurosurgeon, to be an insect surgeon. So the cockroach milk begins as a liquid at first, and it contains these milk crystals that are full of nutritious proteins and stuff. And then as the young grow, the the milk begins to

sort of like solidify into bigger solid crystals. And Dr Stay apparently developed a process for quote milking these cockroaches. Speaking to NPR, she described the process. I guess pretty simply, she said, quote you substitute a filter paper in the brood sack for the embryos, and you leave it there. After a while, you take it out and you get the milk. Okay, it's kind of a stuff of washcloth into the roach and then eventually you take it out and ring it in, ring it out. That's yeah, that's

about right. So you may have seen some articles about this a couple of years ago because there was a new study in analyzing the contents of this cockroach milk, and this study was done by a team led by the Indian biochemists Supermannion Ramaswamy, and the researchers found that it was super nutritious. Quote, a single crystal is estimated to contain more than three times the energy of an

equivalent mass of dairy milk. This unique storage form of nourishment for developing embryos allows access to a constant supply of complete nutrients. And by the way, of course, the way this was covered in the press was there was just headline after headline and CNN and everywhere saying the cockroach milk is the next super food. I'm I'm not grossed out by that. I was as grossed out as

I am by by roaches us. Really, um, I think that falls in line with a lot of what we've been seeing about the consumption of insects, and sects is the protein source. The future is going to be a place where either you eat the bugs or the bugs eat you. Into ma Fiji is the future, and I think there's no doubt about that. I mean, it is a healthy source of protein. That's I think going to be an incredibly important meat substitute in in on future Earth. I have to give a quick shout out to the

Audubon Society's UH Insectarium in New Orleans. UH wonderful museum with so many different live insects species and some arachnet species to check out. But they also have an area where every time you go you get to try a few different um food items that have been prepared with insect protein. And did you try, Oh, I do it

every time. Did you like it? Yeah? Well, they really try and make sure that it's something that you will and candy, you know, so it's generally something sweet you know that kids are gonna be into, essentially, you know, cookies topped with meal worms, that sort of a thing.

But it's very I think it's very instructional and insightful and I'm I'm super glad that they do that and provide that kind of uh, you know, educational content in addition to just learning about these different insect interactant species.

I didn't write down what the reference for this was, but I did look at a press release about a study that found that if you wanted to get people, I think what it was was, if you wanted to get people to agree to eating insects, you couldn't just appeal to the idea that it was better for the environment or that it was nutritious. You had to convince them that it was a delicious delicacy and if you

could do that, they would eat the insects. Interesting. I, yeah, I would love to look at this topic more and see what what people were doing along those lines, because we often come back to the fact that, like, what's the difference ultimately between eating various types of insects in eating shrimp or crawl dads or what happened? Yeah, lobster lobster? Why is that different? Yeah? So, yeah, I would love to talk about about insects more in the future. But

I've got en off topic here. Let's get back to that delicious roach knock Well, So I brought that up just to say that it's probably not true that cockroach milk is the next superfood. I think those were just some headline grabbers. Uh. Number one, we don't know that the milk is safe for human consumption. Humans can often become allergic to cockroaches. We don't have a way of milking them at any kind of volume. So it is

really interesting research. Nonetheless though a couple of reasons, but generally it has to do with the idea of studying the proteins in these crystals in the roach milk to see if they can be replicated in other production scenarios, say by e coal i or by yeast, in ways

that could deliver better technologies for medicine or nutrition. And I was reading an interesting blog post by a biologist or entomologist named Joe Ballinger, and in this post he pointed out that the real discovery here was that there's this protein structure in the in the cockroach milk that includes a protein that kind of serves as a delivery pocket that could be used in other context to shuttle

drugs or substances around inside the body. And of course that's relevant anytime you've got some kind of delivery or micro delivery system that's relevant to future medicines. As for taste, on the other hand, reportedly one of Ramaswami's colleagues tried the cockroach milk on a dare I think maybe because he lost a drinking game or something, and quote he said,

it doesn't taste like anything special. Well, I wonder how much you drank though, Like essentially, if he just its like a you know, he dabbed a tiny droplet of it, or if he had like a full milk glass of the stuff, like you drank a quart of it. Yeah, I imagine he just came from a million cockroaches, the milk of a million cockroaches. It does sound lovely, doesn't it. Well that's it for our sampling of non mammalian milks

to discuss here. You know, we didn't even get into some of the fictional milks out there that have been consumed. How about those creatures in the most recent Star Wars films. Oh, in the Last Jedi or Skywalkers drinking? Is it green or is it blue? Milk? That comes? Yeah? Oh, that that's like the best scene. I loved that. It kind of made the movie for me. Yeah, I enjoyed that film. I did too. Um. You know another one that comes up. It's been a long time since I've seen this, but

the David Cronenberg adaptation of William Burrows Naked Lunch. I believe the mud wump creatures in that film UH secreted some sort of substance that was consumed by by various characters. It's been a while since I've seen it. I don't exactly remember what the whole deal was there, I must confess I've never seen it. Oh, it's it's interesting and the book is a classic of its generation. But off hand, I can't think of any other you know, key like

alien milks or monster milks and UH in cinema or fiction. Though, this would be a good thing to to call out to our our listeners about what what are some of your your favorite or at least notable examples of of non mammalian UH, you know, a fictional creature milks out there? And indeed, I want to know what dinosaur milks other

people would like to consume. Now, as I said earlier in this episode, while I've really enjoyed exploring this anomalous non mammalian milk, we could probably do a whole show in the future just on the magic of true milk. Of mammal milk. It is a fascinating subject and there's a lot we didn't even have time to talk about today. Likewise, I would love to do an episode that goes more in death on cockroaches. I mean there there's a whole lot there that we didn't even touch on here today,

or squash beneath our boot they're six legged saints? All right? Well, um, uh we thank you for listening to this episode within which we discussed the milk of the six legged Saint, and uh we hope you'll tune in some more. We have a couple of other holiday episodes coming up, but more than I more than I expected. But I think I'm I'm embracing the holidays a little more this year. You've been leaning in. I have people out there. You're gonna be surprised all the stuff Bert has wanted to

talk about this month. I'm I think I'm giving in to the holidays this year. I finally realized that it's not it's not courage to fight it, it's courage to to give in. Uh. To paraphrase a quote from one of my favorite holiday films, Ravenous. Uh, so hey, if you want to uh listen to other episodes of Stuff to Blow Your Mind or keep an eye out for new ones. Head on over to the mother ships stuff

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