How Many Babies Should You Have? (featuring Katie Goldin)

Daniel and Kelly chat with Creature Feature's Katie Goldin about babies and how much to care for them. See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:05Kelly Weinersmith?

  Daniel, did you want to ask an alien-related question? Or are you good?

• 0:11Daniel Whiteson?

  Oh, my gosh. The answer to that is always yes.

• 0:15Speaker 02

  Green is the answer.

• 0:17Kelly Weinersmith?

  Green!

• 0:20Daniel Whiteson?

  Yeah, Katie, my question is, what color are alien nipples?

• 0:23Speaker 02

  Hmm, you know what? I've always imagined them as lavender. Isn't that funny?

• 0:31Daniel Whiteson?

  Maybe they also taste like lavender, yeah.

• 0:33Speaker 02

  Hey, you know what? We're getting into some real strange territory here.

• 0:38Daniel Whiteson?

  That's a little taste of the conversation we have on today's episode. It's not about aliens, mostly, though it is a little bit. And it's not about nipples, mostly, again, though it is a little bit. It's about babies. How many babies should you have? Some critters have lots of babies and hope a few survive. Others have just a few babies and take extra special care of them. What's the best strategy evolutionarily? Why do some critters choose one or the other? Does biology make any sense at all? Or is it just depend? We'll dig into that on today's episode of Daniel and Kelly's Extraordinary Reproductive Universe.

• 1:13Kelly Weinersmith?

  So on today's show, we're talking about the birds and the bees. So decide ahead of time if you think that's an appropriate topic for your children. Thanks for listening.

• 1:36Daniel Whiteson?

  Hi, I'm Daniel. I'm a particle physicist, and I have two kids so that neither of them have to be the middle child.

• 1:43Kelly Weinersmith?

  Hi, I'm Kelly Wiener-Smith. I am a parasitologist. I have two kids, because that's all I could handle.

• 1:52Speaker 02

  I'm Katie Gold, and I host a podcast called Creature Feature. I have a dog so that she doesn't have to be a middle child.

• 2:04Kelly Weinersmith?

  Katie, it's so great to have you on the show.

• 2:05Speaker 02

  Yeah, I'm so excited to be here. I too love parasites, by the way. So we've got that in common.

• 2:12Kelly Weinersmith?

  I mean, that's the most important thing to have in common, I think.

• 2:14Speaker 02

  Yeah, that was what got me so into biology is a class I took. The official title of the class was like about mimicry, but the professor who ran the class was like so interested in parasites. That was basically all we talked about. And it's like, he made the right call because that was super interesting. And it's like, I love hearing about all these weird little freaks and I gotta know more.

• 2:37Daniel Whiteson?

  What if there was a parasite that affected the host and made them interested in studying parasites?

• 2:42Speaker 02

  I'm probably chock full of that.

• 2:48Kelly Weinersmith?

  Carl Zimmer's book Parasite Rex like changed my life.

• 2:51Speaker 02

  Yeah.

• 2:51Kelly Weinersmith?

  I was gonna be a parasitologist after reading that.

• 2:53Speaker 02

  Seeing the little isopod, that's the parasite for fish, just like peeking out from a fish mouth going like, hiya, like that altered my brain chemistry forever.

• 3:02Kelly Weinersmith?

  It's pretty awesome. So I was talking to my friend Stacy Farina the other day. And so the story with that isopod goes that it like eats the fish's tongue and replaces the tongue. And she studies fish like skeletal stuff. And she was like, you know, I've looked at a bunch of them and the tongue is still there, guys.

• 3:18Speaker 02

  Yeah.

• 3:18Kelly Weinersmith?

  What? So I think they're actually just like clinging to the tongue and they're eating stuff, but they haven't really eaten the tongue, which I think is part of like what the pops eye.

• 3:27Speaker 02

  Well, it's, yeah, it's like the idea that they're now acting as the tongue. I thought they fed off of the blood supply. So they may cause some atrophying of the tongue, but it's not so much that they eat the whole tongue and then replace it. It's that they're there, they're stealing nutrients from the fish. And then when they leave the fish, usually the fish doesn't survive because it's basically mangled its tongue to the point where it can't use it as much anymore. That's my understanding. But also, I think we have a fairly poor understanding of them because it's not every day that you find these little guys because you'd have to just like open up a bunch of fish mouths of like, let me see inside your mouth, what you got in there?

• 4:06Kelly Weinersmith?

  You know, all the best stories, Katie.

• 4:09Speaker 02

  I look in a lot of fish mouths.

• 4:10Daniel Whiteson?

  And that's why we invited Katie on the podcast today to talk to us about babies.

• 4:16Speaker 02

  Yes, which hard segue from fish mouths to babies.

• 4:23Daniel Whiteson?

  It's really hard to keep you guys on track, but I'm doing my best here.

• 4:29Kelly Weinersmith?

  Well, I mean, whenever we get the chance to talk about parasites, we will. But pulling back, so the reason we're talking about babies today is because we had a question from a listener, Nathan Ryan. He wanted to know about the benefits of having lots of babies relative to the benefits of just having a few. And so he was like, why would you ever have just a few when you could just flood the environment with babies? And ecological theory has a lot of ideas about that. And so I thought today we would talk about how many babies should you have?

• 4:58Daniel Whiteson?

  Thank you, Kelly, for taking us back on track and away from parasites, as difficult as that is for you. I love this question because in his email, he specifically mentions the two kinds of strategies, R strategy and K strategy, which describe having lots or few babies. That's really cool because I'm excited whenever I see a theory in biology, when it's not just descriptive, like naming the parts of the flower, but building a mathematical model to understand the dynamics and how it all works. See, even underneath biology, there has to be math. So we're going to dig into this question by walking through a bunch of examples of extremes, lots of babies, a few babies, and then thinking about whether the current theory about R and K strategists is actually working or not.

• 5:41Speaker 02

  This is such a good question in both personal lives and in evolutionary biology.

• 5:47Daniel Whiteson?

  Do you think Nathan is considering whether to have like two or like 50 kids?

• 5:53Kelly Weinersmith?

  I think he better be considering whether he wants two or 50 wives if he's going to have that many kids. That's a complicated question.

• 5:59Daniel Whiteson?

  Well, he could be a sperm donor. You never know, right?

• 6:01Speaker 02

  Right?

• 6:01Kelly Weinersmith?

  Yeah, no, that's a good point.

• 6:03Daniel Whiteson?

  What do you think is the maximum number of kids any individual human has ever had? Genghis Khan?

• 6:09Speaker 02

  You know, I wouldn't be surprised if some of those warlords just like did get around enough to have like 100 kids, not by one person. That would be. Not possible.

• 6:20Daniel Whiteson?

  Right.

• 6:21Kelly Weinersmith?

  We all have limits.

• 6:22Speaker 02

  You know, I think a lot of that, though, is probably them thinking they have 100 kids. Or it's like, those are my kids too. And got news for you, buddy. Probably not.

• 6:31Kelly Weinersmith?

  You don't always know. That's one of the benefits of being the woman. You can be sure.

• 6:35Speaker 02

  Yes, usually, in most circumstances, yes.

• 6:39Daniel Whiteson?

  I remember reading that there was a woman in the 1700s who gave birth to 69 children.

• 6:44Speaker 02

  How would that even work? Because...

• 6:46Daniel Whiteson?

  It's 16 pairs of twins, seven sets of triplets, and four sets of quadruplets.

• 6:51Speaker 02

  And she lived through all of it.

• 6:54Daniel Whiteson?

  And 67 of the 69 survived. But this is from the 1700s and it's sort of like stories and not like really well documented.

• 7:02Kelly Weinersmith?

  Yeah, that would be intense.

• 7:04Speaker 02

  I have a hard time believing that, maybe just because I simply don't want to believe it like that.

• 7:12Kelly Weinersmith?

  It boggles the mind. It does. Yeah. Yeah, I don't think I want to believe it either, but let's jump into the main episode then. So we thought that first, if you're thinking about how many babies you should have, then you should think about how much energy it's going to take for each one of those babies from you. So how much energy is it going to take to protect and provision the young? And actually, we're not really talking about humans at all today. We're talking about non-human animals. And so let's take a little walk through who does the care in different animals. And so I'll start with fish. Actually, in fish, the males do a lot of the care. And you know, this is possible because most of the time eggs are put out into the environment and fertilization happens externally. And so, you know, either one of them could be the one who splits.

• 7:57Kelly Weinersmith?

  But for whatever reason, it's been the males who tend to stay. So for example, small mouth bass and large mouth bass, the males will sort of use their fins to clear out an area, like a little depression where a nest will be. And then a female comes by and if she decides the male sexy enough, she'll deposit some eggs and then the male will deposit his sperm. And then it's his job to stay there and use his fins to aerate the eggs and make sure there's fresh water passing over them that through diffusion can like get into the eggs to keep those guys alive. And then also make sure that no predators eat those eggs because they're amazing little balls of energy that would be great for like little minnows or crayfish. And so he's got to like defend the nest.

• 8:37Daniel Whiteson?

  Tasty little omelet of babies right there.

• 8:40Kelly Weinersmith?

  That's right. That's right. Pre-made.

• 8:43Kelly Weinersmith?

  And so I think it's pretty energetically expensive. They don't tend to eat while this is happening. And it's sort of not clear why, but maybe it's because they can't control themselves and they might eat the eggs. So anyway, they tend to not eat. It's a lot of work, but the males are doing most of the care. And so the eggs hatch, they swim up. And when they swim away, the male's job, for the most part, is done. He stays with them for a little while, but then they go off on their own. That's quite different than what happens with birds, right, Katie?

• 9:07Speaker 02

  Yeah, I mean, birds have a lot of different strategies. You have a lot of bird species where it's the female taking care of the offspring because she lays the eggs and she, of course, has to keep the eggs warm under her body so she stays with the nest. But you also have a lot of species of birds who work together. So you have a pair of parents, particularly in harsher environments. So seabirds in particular, penguins, obviously, in their very harsh Antarctic environments. There are other species of penguins that live in warmer environments. But an amazing example is great hornbills. So they are a species of bird that go to extreme lengths to protect their eggs.

• 9:48Speaker 02

  The males actually will seal the females into a hollow inside a tree using his own feces and her feces in a bit of mud to create sort of a plaster.

• 9:59Kelly Weinersmith?

  Beautiful.

• 10:00Daniel Whiteson?

  Oh, biology.

• 10:01Speaker 02

  Yeah, and then they leave a tiny hole and the male will go out and very devotedly bring back food for the female and then for the chicks once they hatch. And the reason that there's so much care in these situations of both parents working together is environmental stressors. So for the hornbills, it's in the places that they live in Southeast Asia, in these forests, there's a ton of predatory snakes who eat eggs, eat chicks. So so many arboreal snakes that creating sort of a sealed off, you know, bunker for the female and the eggs is really important. For seabirds, there's a lot of kleptoparasites. Those are other birds that want to steal resources, including eggs,

• 10:46Speaker 02

  including eating chicks. It's just a very, very harsh environment, particularly the ones that live in cold environments. And also finding food is difficult. They have to leave the colony, go out to sea, go fishing. And so both parents need to kind of like switch off and alternate in terms of like taking care of the egg, taking care of the chicks. If they didn't both put all of their effort into it, most likely their chicks wouldn't survive. And also, just an interesting note, in species of birds where they're both working together as a pair, usually there's not as much sexual dimorphism, meaning like both of the male and the female look very similar. Also, when they're mating, both of them will often do some kind of mating display and try

• 11:31Speaker 02

  to impress the other mate equally. Because they're both putting in so much effort into the offspring, they're both equally trying to assess whether their mate is going to be good. Whereas in a lot of other species, where the female is the one doing most of the child rearing, it's the male that's trying to impress her because she's the one putting all of this investment into the offspring. Whereas the male is just kind of like going around, sowing his wild oats. So for him, he doesn't need to be as choosy, whereas the female needs to be really choosy.

• 12:01Daniel Whiteson?

  So in this scenario where the female gets sealed in with the eggs and cares for them, do you think she's like into that? Or is she like trapped in like a slave in his like weird poo palace that he builds for her?

• 12:13Speaker 02

  She's into it. She can actually kind of Kool-Aid man break out anytime she wants. But she's in there. And as long as the male comes and like feeds her, she will stay there with the eggs, take care of them. If the male stops feeding her, I think she will break out and leave the eggs. And so there's a mutually beneficial investment there. Like the male coming back to feed her. Usually the male would only not come back if he came to some devastating end. So the female's completely cooperates in that she actually helps build the wall as well. So it's not like, not a cask of a monteado, but with hornbills.

• 12:52Daniel Whiteson?

  How would you have felt Kelly, if you've been sealed into a room with your babies by your husband's poop?

• 12:57Kelly Weinersmith?

  I mean, our house was pretty messy when we first had our kids. I don't know how different that was. And the diapers were piling up. I guess it wasn't Zach's feces?

• 13:07Speaker 02

  Right.

• 13:08Kelly Weinersmith?

  I think I would have left even with young people in the house.

• 13:12Speaker 02

  But he's getting you Uber Eats like all the time. So that's an important aspect of it.

• 13:17Daniel Whiteson?

  But so the big picture here is that we're seeing lots of different kinds of scenarios, different strategies in different scenarios. And so the idea is that they're responding to the different situations they're in by developing these different strategies?

• 13:30Speaker 02

  That's right. Also, when you have major differences among different types of animals, so like for instance, mammals, usually it's the female doing most of the caring for young. And a big reason for that is lactation. So like mammals, mammary glands, mammals have this ability to lactate and feed their offspring. And this is how they care for very young babies. And so usually, not always, this means that the female is the one doing the primary caregiving for the offspring. You do see this, of course, in other types of animals. So like, there's a type of limbless worm-like amphibian called a Sicilian, which actually has something akin to milk.

• 14:14Speaker 02

  Some species have this like viscous fluid that it produces from its cloaca that the offspring feed from. Like some species, they actually allow their offspring to sort of chew on some like thick nutritional skin that they have, a little excess mom jerky. And in these situations, the mom actually offers parental care to the offspring. But also in mammals, another exception is that there's a lot of very social species of animals where there's both male and female parenting. I mean, humans is an example. There's also allo parenting, which is when either loosely related or non-related individuals take care of the offspring that is not directly theirs. That's like common in a lot of different mammalian species.

• 14:59Speaker 02

  And that culminates into A version of mammals that actually becomes somewhat more insect-like, like naked mole rats who have a eusocial system where they have a queen who reproduces and everyone else is basically facilitating the queen's reproduction. So that's like an extreme example of mammals going more towards like a bee ant colony type model.

• 15:22Daniel Whiteson?

  I've heard this story, I think it may be apocryphal, and I want to ask you that in humans, it's possible, though difficult, for males to lactate, given the right circumstances. Is that true or not?

• 15:34Speaker 02

  It is true. It's basically like hormones will determine lactation. So if some men naturally will produce some hormones that may actually cause them to do a little bit of lactation. And actually, if someone takes hormones, you can induce lactation. And so, you know, yeah, I mean, honestly, like the differences between, say, like male and female phenotypes in humans is so guided by hormones that when those are either, you know, you have atypical levels of them, or you introduce synthetic hormones, you can completely alter the phenotypic representation. That includes functions like lactation.

• 16:16Daniel Whiteson?

  Does that mean that males have mammary glands? They're just not active?

• 16:20Speaker 02

  Yes, yes, essentially, yeah.

• 16:22Daniel Whiteson?

  Mind blown.

• 16:23Speaker 02

  Yeah, you've got nipples, you've got-

• 16:25Daniel Whiteson?

  I was aware of the nipples. Thank you.

• 16:30Speaker 02

  Just making sure.

• 16:31Daniel Whiteson?

  Let's give Daniel a tour here, what he's got going on.

• 16:35Speaker 02

  Oh, these things? Just call them my chest buttons. Yeah, the mammary glands and then are very underdeveloped. But there are like cases with like genetic differences where some men will have larger breasts and larger mammary glands and some men can lactate. And yeah, that can totally happen. But, you know, it's not necessarily going to be enough maybe to feed a baby. But hey, you know what? Get whatever help you can, is what I say. Every drop probably counts.

• 17:04Daniel Whiteson?

  That's right, gentlemen out there. She's not the only one who has to wake up in the middle of the night to feed the baby.

• 17:11Kelly Weinersmith?

  Yes, that's right. Pumping is a great technology.

• 17:14Speaker 02

  Yes.

• 17:15Kelly Weinersmith?

  So when birds, they make that like crop milk. Do the males do that too? Or is that something that just the females do?

• 17:20Speaker 02

  Males can also make crop milk. I think it depends on the species. But yes, you do have a mutual ability, a lot of species to make crop milk. That is not necessarily tied to, you know, just the females. But some animals do, like the Sicilian that I mentioned, like that can be just the female. And probably the explanation for that is in a lot of species, basically unless you're an asexually producing animal, it's the female who's going to be giving birth to the offspring. Or unless you are a seahorse, in which case there's like basically two births, right? Where the female lays the eggs and those develop inside the male's pouch. And then he gives birth to the live offspring.

• 18:03Speaker 02

  So the reason that you will often have cases where once an animal develops sort of a tool for offering nutritional aid to their offspring, that it will be female is because usually it's the female who gives birth to the offspring.

• 18:19Kelly Weinersmith?

  Now insects are heroes of mine because they don't do a lot of parental care.

• 18:22Speaker 02

  No.

• 18:23Kelly Weinersmith?

  Katie, can you tell us about those?

• 18:25Speaker 02

  So later, we're going to talk a little bit about R and K selection. And just very briefly, R selection being you have a ton of offspring, you know, a bunch of cheaply made offspring. And K selection being you have maybe one or two really high quality offspring. It's a very much an overgeneralization, but we'll get into the details later. But insects are sort of like the absolute champions of R selection, popping out enormous numbers of babies and just highly expendable babies.

• 18:59Daniel Whiteson?

  So either you love them or you have lots of them, right? These are the two options.

• 19:03Speaker 02

  Well, essentially, it's a little more complicated than that. But yes, that is like sort of the basic idea behind it. And parental care is really rare in both insects and arthropods. So there are some notable exceptions, such

• 19:20Speaker 02

  As like usually it's the female again for the reason that I said, which is the female that lays eggs or gives birth to offspring. So scorpions will carry their young on their back. Centipedes will kind of curl up in this cute little nest like cradle for her offspring, which is very adorable. There are even types of spiders, like the desert spider, who basically, once she lays her eggs, she starts to digest her own insides and then will regurgitate her own juices for her offspring to feed on. And she does not survive this process. She turns herself into like a mom smoothie and then allows her offspring to eat her. It's called matrophagee, eating one's mother. And the babies will

• 20:04Speaker 02

  eat like 95% of her biomass.

• 20:06Kelly Weinersmith?

  You know, it's not cool. There's no petrophagee. Like, why are there no dads getting eaten?

• 20:11Speaker 02

  There's probably some dads getting eaten. But yeah, the reason that it's usually matrophagee is because of the fact that usually it's the mother that gives birth or lays the eggs. But there are some very rare examples of both the mother and the father and insects taking care of their offspring. The only example I can think of, there may be more, but this one is also really cool, is burying beetles. So these are beetles that will find the carcass of some small animal and then will bury it. And the reason they do this is so that they can lay their eggs on a source of food. So they bury it to keep it away from other competitors. And then they lay their offspring in this sort

• 20:53Speaker 02

  of like little den of rotting meat. And then they actually will stay, both the mother and the father, burying beetle will stay and protect their offspring. So they'll maintain the larder, make sure they have plenty to eat, and then they'll fight off competition and predators until the larvae pupate into their more adult forms. So that's super rare. It just doesn't happen very frequently in insects or in arthropods because their usual technique is just have a huge amount of offspring and statistically, a lot of them are going to make it.

• 21:25Kelly Weinersmith?

  So I think any of the moms or dads out there are probably feeling a little bit better about what we went through when our kids were young right now, after hearing about the insect examples. But let's go ahead and take a break. And when we get back, we'll talk a bit more about the costs associated with having babies.

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• 24:02Kelly Weinersmith?

  And we're back. So we've gone through and we've talked about the different ways that the responsibility of taking care of the kids tends to be divided up in the animal kingdom. So now we're going to dig into some examples of it being costly to have offspring. And I think for most of us who have had kids, we're like, yes, of course it's costly to have offspring. Like, a bunch of us moms lost weight while we were breastfeeding because it's calorically expensive and you're not sleeping. And, you know, it's obviously costly. But that's true for animals, not just humans. And there are some really nice examples of this. So for example, David Lack did this long-term study of these birds called great tits, Paris Major. And confession, I didn't realize this was a bird species the first time I heard about these. And a person who ended

• 24:45Kelly Weinersmith?

  up being my PhD advisor started talking to me about great tits. And I just had a, like, deer in the headlights moment. And it took me a second. He said something about eggs. And I was like, ah, I think we're talking about birds or fish. And eventually-

• 25:00Speaker 02

  The first time I heard about great tits was when I was on a bird watching expedition with a bunch of senior citizens when I was in high school. And this sweet little old lady leaned over to me and says, now you have younger ears. So see if you can hear some great tits.

• 25:18Kelly Weinersmith?

  That doesn't make any sense, lady.

• 25:22Speaker 02

  Keep your eyes peeled for great tits, just coming from this octogenarian. It was a wonderful moment.

• 25:28Daniel Whiteson?

  She's probably seen a lot. She knows, right?

• 25:30Kelly Weinersmith?

  It's nothing you ain't seen before. Maybe we should put a little warning at the top of this episode.

• 25:36Daniel Whiteson?

  But more broadly, like, we're hearing these examples about, like, different strategies, males taking care of the babies, females taking care of the babies. What do we learn sort of broadly from these examples? Like, are there obvious trends here where people respond in certain ways to certain circumstances? Or is it just like a scattering of examples? And the answer is, it all depends.

• 25:56Speaker 02

  There are patterns, for sure. There have been attempts to kind of put the patterns into much more simple mathematical equations, which sometimes work, but then sometimes they fail. But in general, there are patterns, but because there are so many essentially factors that are a component in these evolutionary quote unquote, choices, it can be difficult to like, see the pattern from the noise, but they do exist. And there have been some like observable patterns that have been found that can kind of help sway the decision in terms of like, what type of offspring strategy species end up falling into, right, Kelly?

• 26:37Kelly Weinersmith?

  Yeah, so we are essentially making the argument that it depends today, which Daniel will not be surprised to hear. So I found this quote from a textbook that I used in grad school, and it's, "The evolution of care behavior is complex, and we are still far from fully understanding which factors really influence the evolution of care in both males and females. Models or arguments like the ones presented above in this textbook may also prove too simple because they generally consider just a few factors at a time." So we're talking today about, you know, some of the different solutions that evolution has landed on, and some of the different factors that influence the decisions that end up getting made over evolutionary time. But it really does depend.

• 27:17Daniel Whiteson?

  Life is messy, and lots of factors must come into play: predation, and environment, and variability, and all sorts of crazy stuff. It'd be amazing if you could boil it down to just a few variables like you can in physics. I don't know why physics ever works, frankly.

• 27:31Kelly Weinersmith?

  Yeah. We're going to talk about a lot of variability, and then we're going to narrow down a little bit on one attempt to sort of summarize what we see and why we see it. And then we're going to talk about how that sort of way of summarizing things fell apart, and how now we're back to trying to find more complicated models that include more variables.

• 27:49Daniel Whiteson?

  All right, now I'm ready to talk about great tits.

• 27:53Kelly Weinersmith?

  That's great.

• 27:54Speaker 02

  It's always good to get into the math before we start talking about great tits.

• 27:58Kelly Weinersmith?

  That's right. That's right. That's how most of these conversations work out. So there's this researcher in England. Great tits are these tiny little birds. And there's this population that's been monitored for decades and all of the birds are as many as possible are caught every year. They're banded and then you look to see who's coming back year after year. These birds tend to lay one set, one clutch of eggs once a year. And the army of graduate students who were working on this for decades would go out and they would count how many eggs. They would weigh the birds soon after they hatched. And then they'd measure survival by determining who came back. And they were looking at a large enough area that I think they decided that, you know, the birds who flew to join a different population. That was a negligible number of birds. So they pretty much were keeping track of everybody.

• 28:43Kelly Weinersmith?

  And they noticed that these birds usually lay eight or nine eggs. And that the more eggs there were in a nest, the smaller the offspring would be. And you could test this by moving eggs between nests and looking to see if you like, make the parents feed more offspring. What does that do to the size of the birds? And the parents are out from like dusk to dawn, dawn to dusk. That would be it. From dawn to dusk, trying to catch.

• 29:09Speaker 02

  Depending on how you look at it.

• 29:10Kelly Weinersmith?

  Yeah.

• 29:11Daniel Whiteson?

  Depends whether they're good parents or they're just like out drinking.

• 29:14Kelly Weinersmith?

  Yeah, right. Drinking caterpillar juice or something.

• 29:18Speaker 02

  Delicious.

• 29:19Kelly Weinersmith?

  Yummy. And they found that the more birds they had to feed, the smaller the birds were. And then if you look at those small birds, they're less likely to survive and show up again in the population as adults. So if you have too many babies, those babies don't seem to make it. And you've expended all of that energy for nothing. But they did some like mathematical modeling and moving some eggs around. And they ended up deciding like, okay, but it looks like the birds are producing fewer eggs than we think that they could be producing optimally every year. That they could feed enough and enough of them could come back in the future. Why aren't they making more eggs? And the idea here was that you're not just trying to maximize the number of eggs that you're producing in one year. You're thinking about your lifetime reproductive success. So if you go.

• 30:02Kelly Weinersmith?

  All out and you raise as many eggs this year as you can, you're probably going to exhaust yourself and not be able to survive until the next year so that you can have more offspring. And to be honest, because ecology is complicated, as far as I know, they didn't find good evidence for that in this system. But they have found evidence for that in other systems. So like in European kestrels. So these are birds that are predators and they pick off little mammals. They found that if you put extra eggs in a nest and like those adults had to feed more babies, the babies were less likely to survive to adults and the adults who had more babies in their nest were less likely to show up the next year. So they were less likely to like survive the winter.

• 30:41Speaker 02

  It just sounds though, like they, instead of like showing up, I know what you mean is their survival rates, but it does kind of sound like when you gave them too many kids, they're like, that's it. I'm out. I'm leaving. Done.

• 30:51Kelly Weinersmith?

  That's right. I'm gonna go become a dancer. I'm done. But you know, this is ecology, right? So the answer has to be it depends. And even though you feel like you have a nice model, a nice theory for understanding how this stuff works. If you look in a different system, you don't always find support. So David Resnick studies guppies. These are these tiny little fish that you find in Trinidad. And he took them into, I think this was a lab study and he compared the females who were paired with a male and could mate to females who didn't have a male. And the idea was supposed to be that the females who had to produce young would end up weighing less because it's energetically expensive than the females who didn't have to produce young. But they didn't find that. The females who had to produce babies just ate more.

• 31:33Kelly Weinersmith?

  That's what I did for sure. And so they ended up being in just as good shape. And so, you know, this kind of stuff can depend on like, how many resources are available in the environment? Like if you're feeding baby chicks, but it's a year where there's just loads of insects, maybe it's one of those years where the cicadas come out of the grounds and there's just food everywhere, then you know, you don't have as many trade offs.

• 31:56Daniel Whiteson?

  So if you can just sit on the couch and eat Ben and Jerry's, then you should have lots of kids.

• 32:00Kelly Weinersmith?

  And so that quote from earlier is about how there's lots of other factors to consider.

• 32:05Daniel Whiteson?

  Which flavors of Ben and Jerry's are available, this kind of stuff?

• 32:09Speaker 02

  People often ask, like, can I feed, say, wild birds? And the answer is, it depends, again, because one of the problems, if you feed wild birds too much, you actually give them a false sense of security in terms of like, oh, there's a lot of plenty, I can have a lot of babies. And then they end up having more babies earlier, and then they might miss key points in terms of like, some species maybe time their offspring to the emergence of certain insects, right? Like, they follow the breeding cycle of caterpillars or other insects. And then they may, if you give them too many resources artificially, they may actually have more offspring earlier. And then when they migrate, right? They're not, they don't stay in your backyard forever, then they migrate, and then they

• 32:54Speaker 02

  don't actually have the resources that they kind of were led to believe they would have. It can actually cause a population crash. So like, there's a lot of like weird, unexpected consequences where a lot of species have this kind of like timing system, and they can also kind of, they can change their breeding behavior based on the stress and these resources that they have available to them.

• 33:18Daniel Whiteson?

  What if you feed wild birds, but you do it consistently? You don't just like yank it away from them?

• 33:23Speaker 02

  Well, it depends. Like, if they migrate, then you'd have to follow them. It's like, all right, where are you going? Get on a plane.

• 33:31Kelly Weinersmith?

  You tag them and migrate with them.

• 33:33Speaker 02

  And if you're just feeding birds consistently and they stay in your backyard, that's how we got chickens.

• 33:39Daniel Whiteson?

  That's not so bad. That's delicious.

• 33:44Kelly Weinersmith?

  You can also transmit diseases at feeders.

• 33:48Speaker 02

  That's true.

• 33:49Kelly Weinersmith?

  It had been like 15 minutes since we had talked about parasites, so I had to pull that back in.

• 33:53Speaker 02

  When you have a really crowded public feeder, you've got a lot of birds, you know, rubbing up against each other, so then they can transfer diseases. So like, especially when there's like avian flu going around, it's probably not a good time to take in those feeders.

• 34:04Daniel Whiteson?

  We had a bird feeder in our backyard, and there was a blue jay in the neighborhood who really liked, like, the bigger seeds. I think it was the sunflower seeds. And he was also a bully, so he would like chase away all the other birds, and then he would sift through, just like throwing seeds left and right to get to the sunflower seeds and gobble them up, but making a mess everywhere. And all the other birds were scared. We had to like try to chase this guy away.

• 34:26Speaker 02

  Yeah.

• 34:27Kelly Weinersmith?

  We have a family member like that. We stopped inviting them to bed.

• 34:32Kelly Weinersmith?

  So we've talked about a variety of different ways that nature has sort of solved the problem of who takes care of the offspring, how many offspring do you have, but sometimes it's complicated. So let's move on to this idea of R and K strategists. So this idea was meant to sort of come up with a theory that would explain why sometimes you get organisms, species that make loads of offspring, and then other times you get species that just make a few offspring. So what kind of conditions would promote doing something crazy like having thousands of offspring? So the idea here is that maybe you have some environments that are just changing all the time. They're unpredictable, maybe like periodically fires

• 35:14Kelly Weinersmith?

  come through and they just sort of devastate the environment. And so it's not necessarily that like resources are limited, it's just every once in a while, something catastrophic happens. And in that case, as the theory went, the idea is that you should produce loads of offspring and you should start producing these offspring as young as you can so that you can get as many chances at making offspring as possible and that you can fill any new niche that opens up by having all of these new offspring. Whereas if you're in an environment where there's, you know, a set number of resources, that environment is pretty stable, is pretty predictable, then you should invest in making a few number of offspring that are in really great shape and they're really good competitors because there's going to be

• 35:57Kelly Weinersmith?

  a lot of competition for those resources since everybody's sort of at the limits of what the environment can handle in terms of the amount of resources that are available there for everybody.

• 36:07Daniel Whiteson?

  Does that make sense to you? I mean, I try to imagine myself as a parent in this circumstance. And like, it seems like that makes sense under the assumption that you can do nothing to help your kids survive, right? You should just have lots of them because it's all random. But I'm imagining like, if I have kids in suburban Southern California where things are pretty stable versus I have kids in like post-apocalyptic Mad Max scenario, like, am I going to pump out 100 kids and then just like, let them run crazy free and hope they survive? Feels to me like I'd still be better off having few kids and trying to like, navigate them through the chaos.

• 36:41Kelly Weinersmith?

  Well, evolution has selected our species over time to be really good at making a small number of offspring and we can use our intelligence to sort of help them survive in this complicated environment. I would say that we don't necessarily have the ability at this point to make as many offspring as it would take to think of yourself as an art strategist. What's your take on this, Katie?

• 37:03Speaker 02

  Yeah, I mean, I think it's kind of comes down to probably very complicated statistical probabilities that I have no way of kind of conceptualizing. But, you know, it's sort of like, I'm gonna make a stock market comparison, but I want to make it clear, I don't know anything about investment. But if you have like a really risky market, right, like you diversify your portfolio in general, right? Whereas maybe if you have a more stable market, it's like, man, I know that everybody loves apple juice, so I'll keep investing in apple juice. I don't mess around with the stock market because I truly don't understand it.

• 37:39Daniel Whiteson?

  I don't think apple juice is a growth industry, Katie. It's not a good investment. Don't take advice from Katie, folks.

• 37:45Speaker 02

  If I drink enough, it's a growth industry for me. But like, one thing is that you can think of it in terms of like an individual's success, right? Like, I'm a parent, I can like, make sure my child reaches adulthood. But you can also look at it in terms of just like, the spread of a bunch of genes. And there have been some sort of like, back and forth arguments about like, what matters more genes or phenotype, right? But in general, like, sometimes you may have a situation in which having a ton of offspring and not taking care of them, but just leaving it up to chance, is the best strategy, even if like you say, take care of your offspring. Because say there's a disease that comes around, like,

• 38:30Speaker 02

  no matter how good you take care of your offspring, a disease that comes hit you, there's nothing you can do about that. But if you have 50,000 offspring, and one or two of them had a genetic mutation, where they managed to avoid this like devastating disease, then your genes get passed on. And it doesn't matter that you were a terrible parent.

• 38:50Daniel Whiteson?

  Hypothetically.

• 38:52Speaker 02

  But of course, obviously, we do have all kinds of parenting, right? In nature. And so it does mean that there have been stable patterns of both our and K's strategists being able to survive. But it's just that there isn't one single strategy that always wins. The species that we see alive today have not been raining the earth for the past, you know, millions of years. Like so many species have gone extinct or have turned into a different species that survived to today. So like, there's a lot of strategies that were tried and then failed. And then a little different strategy was tried and failed.

• 39:32Speaker 02

  So it's really just about can a species find an amount of stability for a certain chunk of time? And then that lasts for some amount of time. And there's no guarantee that any of the current survivors now are going to last the next million years.

• 39:47Daniel Whiteson?

  I think it's interesting that you talk about like good parenting and bad parenting. It's funny, we put these sort of like moral labels on it and we joke a little bit. But, you know, it makes me wonder if you're the parent in a species where you just sort of like make a lot of them and spray them into the environment and ignore them. Do you still love your babies? Or is it just like not a big a part of your life?

• 40:06Speaker 02

  Sometimes you eat them.

• 40:07Daniel Whiteson?

  Sometimes you eat them.

• 40:08Speaker 02

  Sometimes you eat them.

• 40:09Daniel Whiteson?

  You'll love them for dinner.

• 40:12Speaker 02

  There are a lot of like amphibians and fish that will sometimes eat some of their offspring, just like, ah, it's fine if I nibble on a few of them, right? But again, it's not because they're cruel. It's because of the trade off between your own personal survival and health and being able to bear future offspring and your offspring surviving. In fact, like there are some species of animals that will like fight to the death to protect their offspring. Like I've seen elk try to stomp the dickens out of a mountain lion to save her offspring. Whereas some animals who have a higher fecundity, like they see a predator and they're like, all right, I'm out because I can have babies in the future.

• 40:53Kelly Weinersmith?

  Well, we have hit optimum D K E U episode here because we've talked about poop and cannibalism. But we're still going to go ahead and do one more session, even though we've hit all the high points. So let's go ahead and take a break. And when we come back, we will talk more about babies.

• 41:19Speaker 03

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• 42:16Speaker 05

  Hey, it's Nile Rodgers, host of Before the Moment, a Lincoln original series. I'm driving across the country, meeting some of today's most fascinating artists. We're exploring the stories before the moment that changed everything. This week, I'm joined by rising star Sienna Sperling.

• 42:35Speaker 06

  My first ever In the World show was when I was 10, and I sang at a pub called The Georgian Devonshire. I was so nervous. I was 10, so they let me in only to sing my song, and then they kicked me out right after. And then I remember I wrote, I've been writing since I was 10, so I wrote this song called "Lady in the Mirror", made this little track with it. But I just pressed it. And I remember I sang this song, and there was like five people in there. And I remember how myself I felt, and I felt like I understood myself and understood what I needed to do.

• 43:02Speaker 05

  So does that take us back to, "I sing just to know I'm alive"?

• 43:06Speaker 06

  Hundred percent, hundred percent, my whole life.

• 43:09Speaker 05

  Experience Before the Moment, a Lincoln original series on the iHeartRadio app, YouTube, or wherever you get your podcasts.

• 43:26Kelly Weinersmith?

  Before the last break, Katie was talking about variability in parental care, how some animals are willing to risk their lives and some just aren't willing to risk their lives for their babies. One of the things that got me really excited about behavioral ecology was that even within species, there's a lot of variability and trying to understand why some animals are great parents and some are kind of miserable is just fascinating to me. Like, I studied smallmouth bass for a while, and after the ice would melt off the lakes in Wisconsin, it was still absolutely frigid, we would jump in and we would try to find every nest in this northern Wisconsin lake. And some of the males, you would approach their nest and you could see just like the shadow of them as they ran off and the minnows

• 44:09Kelly Weinersmith?

  would come in and they'd try to eat their eggs and you just would never see that male again. And then there were other males who you'd be like, trying to figure out where the nest is, you haven't even located it yet, and they would literally like torpedo you in the face and knock your mask off and like, you know, knock your snorkel out of your mouth and they would just keep like ramming into you. So even within species, there's loads of differences and I don't think we understand very well what those differences are. Sometimes it has to do with how big the males are. So like if a male is huge and all of the predators in the lake have little mouths, then he can be pretty sure nothing's going to be able to eat him. So he might as well attack. Whereas if you're the little guy, maybe you don't get gutsy until you grow for a few more years, until

• 44:52Kelly Weinersmith?

  you're big enough that probably nothing can eat you. But there's loads of variability even within species, which I think is just totally fascinating and adorable.

• 45:00Speaker 02

  I mean, that reminds me of like sort of different mating strategies where you have sort of sneaky males versus large sort of jock males, like in salmon and coho salmon. Like, there's the jacks, which are the little guys, and then the hook noses, I think, based on the shape of their face, which are the bigger ones. And the little guys actually do a really good job of sneakily mating with females, whereas the big guys, they may have a more like, secure position in terms of not being preyed upon, but they're less agile and actually the- Jacks tend to be more numerous because what happens is the female will deposit her eggs and the jack kind of like zoom out there and puts his sperm on the eggs and then zooms

• 45:42Speaker 02

  away, right? Like an egg assassin, just like boop, like fertilized. But yeah, it's also like even a single individual can change their strategy based on, say, environmental stressors like kangaroos and wallabies can basically control when they have offspring. It's called embryonic diapause. So it's like when they freeze the development of their embryo, when they feel like stressed or like the conditions aren't right. So they're controlling their fecundity. There's also what we mentioned earlier about cannibalism, like eating your eggs, eating your offspring when resources seem limited or when you're stressed out. Like bears will sometimes do that. Like bears will eat their newly born offspring, like

• 46:25Speaker 02

  black bears. And it's like, well, why would they do that? Well, if it's a weaker offspring or if they're stressed out and they feel like resources aren't good at that time, they actually control whether or not they want to invest in an offspring at that point.

• 46:37Kelly Weinersmith?

  Tough decisions. Our kids don't know how lucky they are to have made it as far as they did, that we never snacked on them.

• 46:43Speaker 02

  Right.

• 46:44Kelly Weinersmith?

  Even when things were scary.

• 46:46Speaker 02

  They think it's terrible when parents eat their chocolate bunnies and they don't know it could be so much worse.

• 46:51Kelly Weinersmith?

  So much worse. I'm gonna have to tell my kids that around Easter.

• 46:54Speaker 02

  Yeah.

• 46:55Kelly Weinersmith?

  It'll be good. I'm a great parent. So to get back to R and K strategists, so we have kind of given some examples of different R and K strategists over the course of this chat. Katie mentions that insects are the classic R strategists. And just like a funny aside, I could never remember if the Rs and the Ks, which one was the fast and lots of babies and which one was the slow and just a few babies. And this morning, my really embarrassing way of remembering was Kelly starts with K and I only had a few babies. And so anyway, anyone needs to remember that in the future. Just think about Kelly only had two babies. But anyway, that was also my way of remembering if I was going to Slovakia or Slovenia to give a talk. Slovakia has a K in it and Kelly's going.

• 47:38Speaker 02

  I remember it with a rapid fire for R and quality with K because I'm good at spelling.

• 47:45Kelly Weinersmith?

  Love it. Okay. So you in our notes have a really great explanation of whale parental care. Do you want to chat about them as like ideal K specialists?

• 47:57Speaker 02

  Yeah, absolutely. So whales are especially the largest whales, blue whales are an excellent example of K strategists, right? Like they fit into the classic mold. They're big, they live a long time, they're intelligent, and they have very long gestation period of about a year. And they only have an offspring every presidential term, essentially like every four years or so. So they are very slow in terms of producing a lot of offspring, but they pour a huge amount of resources into the offspring. They produce about 50 gallons of milk per day.

• 48:36Kelly Weinersmith?

  Wow.

• 48:36Daniel Whiteson?

  That's incredible.

• 48:37Speaker 02

  Yeah. It's also really high quality milk. It's very, very fat dense.

• 48:43Daniel Whiteson?

  Is it delicious?

• 48:44Speaker 02

  You know, I would love to try some hot, fresh whale milk. That sounds very good, especially because we know what their diet is, like a ton of krill. That's got to have a nice fishy aftertaste.

• 48:56Daniel Whiteson?

  Wait, how big is a blue whale nipple? I mean, could a human even actually like get it fresh from the whale?

• 49:02Speaker 02

  You know, I've actually never seen a blue whale nipple, so I don't know. I'm gonna assume it's pretty big.

• 49:08Daniel Whiteson?

  If I Google that, am I gonna get on some terrorist watch list right now?

• 49:12Speaker 02

  You know, I did once Google elephant breasts, and I'm sure I'm on a list.

• 49:17Kelly Weinersmith?

  Oh, no.

• 49:20Speaker 02

  But I meant literally elephant breasts because I was curious about breastfeeding in elephants. And I can't explain everything.

• 49:26Daniel Whiteson?

  Since we're on the topic of Katie's weird history, what is the most interesting animal whose milk you have had?

• 49:32Speaker 02

  Oh, I mean, I think just goat milk. I'm not very exciting. I haven't done anything too adventurous. I wish I could say like, I've suckled on a Sicilian or something, but no, I really haven't. Goat milk. I guess human milk, though, right?

• 49:46Daniel Whiteson?

  Human milk is pretty weird.

• 49:48Speaker 02

  Human milk's pretty weird, but we all drink it as babies.

• 49:50Daniel Whiteson?

  I lived in a small village in France where the grocery store had pony milk available. Yes, little bottles of pony milk.

• 49:57Speaker 02

  Like from specifically ponies, like little ones?

• 50:00Daniel Whiteson?

  From ponies, yes.

• 50:00Speaker 02

  Okay. Why not?

• 50:03Kelly Weinersmith?

  How was it?

• 50:03Daniel Whiteson?

  I vote nay on pony milk.

• 50:07Speaker 02

  Really? It wasn't very good?

• 50:09Daniel Whiteson?

  It was too horsey for me. Yeah.

• 50:10Speaker 02

  Okay.

• 50:11Daniel Whiteson?

  You know how a milk sort of reminds you of the odor of an animal like goat milk? Sort of tastes like the way goats smells?

• 50:16Speaker 02

  A little bit.

• 50:17Daniel Whiteson?

  Not a fan of the way horses smell.

• 50:18Speaker 02

  I feel that. I definitely can only handle a certain amount of a goat cheese before I'm like, I feel like I'm eating the smell of the goat.

• 50:26Daniel Whiteson?

  Exactly. Like I'm licking a sweaty goat or something. Yeah.

• 50:29Kelly Weinersmith?

  It smells and tastes like hay to me and I love it. But anyway, let's get back to blue whales.

• 50:33Speaker 02

  Right. So blue whale milk probably tastes like blue whale and the calves actually gain hundreds of pounds of weight every few days.

• 50:41Daniel Whiteson?

  Incredible.

• 50:42Speaker 02

  They grow at an incredible weight. They go from being about the size of like a shipping container to like nearly a football field. Right? So it's wild. It's a wild amount of growth. So this also highlights sort of the interesting trade off between somatic growth, meaning growing yourself and growing your offspring. Whales spend their first parts of their lives just growing themselves to enormous sizes by drinking a huge amount of their mother's milk. And then when they're old enough, they start to filter feed on krill. They're baleen whales. They have those bristle structures in their mouths. They take in huge amounts of seawater and then expel it all out. And then krill, which are hugely abundant,

• 51:26Speaker 02

  a huge source of biomass, get caught in their baleen and then they can swallow that and just they eat. They're like vacuums that are able to exploit a massive amount of biomass in the ocean. It'd be like a cow on land that's just giant and had like a giant sort of like lawn mower mouth that could go and like mow an entire field in like a few hours.

• 51:51Kelly Weinersmith?

  Why hasn't evolution come up with that yet?

• 51:53Speaker 02

  It's coming. Giant terrifying cows are coming, I'm sure. And they'll be shaped like crabs based on other patterns in nature.

• 52:02Kelly Weinersmith?

  We just had an interview with the woman who wrote the review paper and how grumpy she is about how it's been interpreted. But anyway, crab episode coming soon.

• 52:10Speaker 02

  I stand firmly behind my crab carcinization of cows theory.

• 52:16Daniel Whiteson?

  Excellent.

• 52:18Speaker 02

  But yeah, so after this period of growing the self to these enormous sizes, then they can enter into the reproductive period and then spend a lot of resources developing the offspring, taking a year to develop the embryo to becoming the live born offspring, and then just feeding it huge amounts. Basically, they inhabit this evolutionary niche where they invest their resources into being really big. And then when you give birth, your offspring has taken a whole year to develop inside your massive body. So there's very few predators who could actually target your offspring. And honestly, they had very little in terms of competitors and predators until humans

• 53:00Speaker 02

  figured out how to fashion a harpoon and that we liked whale juices for a lot of disgusting uses.

• 53:07Daniel Whiteson?

  That sounds like a title for a great book. Whale juices for disgusting uses.

• 53:12Daniel Whiteson?

  I want to read that.

• 53:14Speaker 02

  Whale juices for disgusting uses. A very highly unethical guide to using whale ambergris.

• 53:21Kelly Weinersmith?

  Yeah. Okay, so we've talked about insects being amazing R strategists. We've now talked about blue whales being amazing K strategists. And now that you feel like maybe you've got this strategy in your mind, I'm going to go ahead and tell you that this probably does not represent reality because it's more of a spectrum when you look into these things. And it's not surprising that things don't fit into little categories because probably the only thing in an environment that matters isn't like how often a fire passes through. And so usually when you find species, you find some like combination of these different kinds of traits. So a classic example is an elm tree. So an elm tree is kind of like a K strategist in that it lives for a really, really, really long time and it gets huge.

• 54:06Kelly Weinersmith?

  And why it has to get huge is because it is competing with the other trees in the canopy. And if you can't get to the top of the canopy, you don't get light and you don't get to survive. And Daniel, this sort of addresses your question earlier about like, well, why wouldn't you always just have a few offspring that you invest a lot in? So for these seeds, they make loads of seeds. I think they can make- Make up to a million seeds in their lifetime and these seeds are tiny. And the only way any of those seeds get to survive is if they happen to end up in a spot on the floor where they get really lucky, like maybe a super old tree that's 100 years old has finally fallen over and died. And now there's a little bit of light coming through the canopy, making it to the forest floor. And your offspring just don't have any chance to survive unless they end up randomly in one

• 54:51Kelly Weinersmith?

  of those spots.

• 54:52Daniel Whiteson?

  It's like waiting for a physics professor to retire and open up a professorship finally.

• 54:57Kelly Weinersmith?

  Right. Or answer your emails. Yeah.

• 54:59Speaker 02

  Completely random.

• 55:01Kelly Weinersmith?

  Yeah, completely random. And so like if you had made five of the greatest acorns in the world.

• 55:08Daniel Whiteson?

  Thank you. My acorns are wonderful. Yes.

• 55:11Kelly Weinersmith?

  Okay.

• 55:11Speaker 02

  A lot of squirrel energy over here. I don't know why.

• 55:15Kelly Weinersmith?

  Yeah, that's right.

• 55:17Daniel Whiteson?

  I'm just trying to imagine what is it like to be a good elm parent? Like, you know, you're really crafty acorns or do you just care deeply about them? Or you're like weirdly irrationally proud of your acorns? I don't know. I was trying to do it.

• 55:29Kelly Weinersmith?

  Anthropomorphizing trees. I never could say that word without stumbling and overthinking it. But, but also if you make like giant seeds, they're going to get eaten by squirrels. And so just for a variety of reasons, the best strategy is to make lots of them every year and scatter them as far as you can and

• 55:45Daniel Whiteson?

  Not care.

• 55:46Kelly Weinersmith?

  And not care. It seems like there's really no better strategy than that. And the environment is selecting for that.

• 55:50Speaker 02

  An animal equivalent to the elm tree are actually a sunfish. They're huge, huge fish, like the size of a kiddie pool. And they're those weird guys that are kind of like flat and they've got the big eyeballs and they're really funny. But you would think like, okay, they're huge so that they can have large offspring that like nobody messes with. But actually their offspring are teeny, teeny tiny. They're only a couple millimeters big. They're nearly like planktonic and they have huge amounts of them. The females can lay like millions of eggs in her lifetime. And so it's kind of like the elm situation where they're just doing like, I'm just gonna scatter a bunch of them. It's a little less clear why they do this versus the elm, right? Because it's not the same situation where

• 56:34Speaker 02

  the elm seeds need to find that perfect location where they don't have to compete with other trees to get sunlight through the canopy. But in the ocean, you have a lot of evolutionary pressures where it's hard not to get eaten in the ocean. And it also takes a lot of resources, right? To create a large offspring. So for the sunfish, even though it seems like they're going towards the blue whale strategy of like, hey, they're big, right? So maybe it's so that they can just invest a lot in one offspring. No, complete opposite. Just a bunch of tiny babies that get eaten up like little popcorn. And then like, some of them, though, happen to keep growing and growing and growing until they're just enormous.

• 57:15Daniel Whiteson?

  So Kelly, if we think that the R strategy and K strategy is a little too simplistic, have we like upgraded our model to understand this in terms of like more variables and it's sort of a higher dimensional evolutionary space?

• 57:28Kelly Weinersmith?

  Yeah, so now we talk about life history strategies and the decisions that animals make are things like, when do you start breeding? How many times in your life will you breed? How many offspring do you make each of those breeding attempts? And how much do you care for them? And evolution has happened upon a lot of different answers to all of those questions. And it depends on lots of stuff like how competitive the environment is, how much food is available, how many other individuals are in the population, how stable is your environment, et cetera, et cetera. There's a lot of different factors that sort of go into these decisions. And so the way we think about it right now involves a lot more variables, and it's quite a bit more complicated.

• 58:08Speaker 02

  Yeah, it's complicated. It's just like the Facebook message, you know, like that's basically like all these mathematicians, all these evolutionary biologists trying to get it down to some nice, beautiful formulas. And the best we can come up with is, it's complicated.

• 58:24Daniel Whiteson?

  In my mind, there's sort of two possible scenarios, or maybe a spectrum of them. One in which like, it's complicated and it depends on lots of factors. But if you knew all those factors, you could understand it. And, you know, everybody is responding to those factors in a way that makes sense to us. And the other is that it's just kind of random. Like, does everything have to have a reason? Like, you know, you might ask, why are there so many different kinds of eye colors in humans? Is there a reason why that is? Or just sort of like, hey, these are the group that survived, and a lot of it is just random. How much of it does need to be explained? And how much of it can we just say, hey, this is sort of just what happened?

• 59:02Kelly Weinersmith?

  Yeah, so that's a great question. I mean, I think we are, over time, having a better understanding of what factors you need to think about ahead of time if you were to predict. Like, if somebody plopped a brand-new species in front of you, we could ask a certain set of questions and have a pretty good guess for what that animal should do. And it depends a little bit on, like, evolutionary trajectory. If it's a mammal, then probably female's going to be the one who's doing a lot of investing. So you'd predict that the males would try to mate with as many females as they could to maximize numbers, and then the females are going to have to invest a lot more heavily in the offspring that they have. And so it is becoming more of a predictive science, but it's taken a lot of work. Let's say you, Katie.

• 59:43Speaker 02

  Evolution is really interesting because you always have an element of randomness, right? Genetic mutation is random, although geologists would disagree, right? An earthquake is quasi-random, right? When it comes to animals, like, an animal certainly can't predict when an earthquake happens or some, like, dramatic environmental change happens. You know, sort of like, whether or not you're just in the right place at the wrong time or the wrong place at the right time, all of those things are these random things. But when you have a system over long, long, long periods of time, that's when that randomness starts to get shaped into something that seems more intentional, seems more like, oh, this feels like this is becoming more and more efficient.

• 1:00:24Speaker 02

  But the truth is that the species that we see today, we are just sort of lucky enough to have this glimpse of the Earth at this period of time where we have all these species. And they are not, like, ideal, optimized creatures in every sense, right? Like, a lot of the evolutionary traits that they have, like, some of them have been selected for, and some of them have been either initially selected for and then evolution switched up on them, right? Like, where their environment switched up and the strategy has to switch, but they never got rid of it, right? Because it either wasn't harming them, or they just never lucked into the gene that helped them get rid of it, right?

• 1:01:03Speaker 02

  So evolution doesn't create perfectly optimized, streamlined animals, but it does create animals that generally Speaking are good at survival. And so there's like some potential randomness, right? Where it's like, just happened to be that this basically worked. It's like an old car that's like, yeah, it's got pretty bad mileage and the carbureator makes a weird noise, but it's still going. And there are species like that where it's like, it's not perfect, but it's still going. Some of it can be a little bit random and certainly not perfect.

• 1:01:37Kelly Weinersmith?

  Yes, I feel not perfectly suited to my environment much of the time. And on that note, Daniel, did you want to ask an alien related question? Or are you good?

• 1:01:49Daniel Whiteson?

  Oh, my gosh, the answer to that is always yes.

• 1:01:52Kelly Weinersmith?

  All right, we can pull back. Do you want to ask your alien question?

• 1:01:54Speaker 02

  Green is the answer.

• 1:01:56Kelly Weinersmith?

  Green.

• 1:02:00Daniel Whiteson?

  Yeah, Katie, my question is what color are alien nipples?

• 1:02:04Speaker 02

  You know what? I've always imagined them as lavender. Isn't that funny?

• 1:02:11Daniel Whiteson?

  Maybe they also taste like lavender. Yeah.

• 1:02:12Speaker 02

  Hey, you know what? We're getting into some real strange territory here.

• 1:02:18Kelly Weinersmith?

  Thanks for being on the show, Katie.

• 1:02:19Speaker 02

  Yeah, absolutely. Thanks for having me.

• 1:02:28Kelly Weinersmith?

  Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We would love to hear from you.

• 1:02:33Daniel Whiteson?

  We really would. We want to know what questions you have about this extraordinary universe.

• 1:02:39Kelly Weinersmith?

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• 1:02:46Daniel Whiteson?

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• 1:02:52Kelly Weinersmith?

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• 1:03:02Daniel Whiteson?

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