Howdy, Extraordinaries. Most of this episode is about social behavior and cooperation in animals, and in particular human animals, but towards the end we talk a little bit about cases where humans and non human animals have not gotten the love that they deserve early on in life, in the implications of that for their behavior, which is a little bit hard to hear, So just a heads up so you can decide if you want to listen to the
last third of the episode or not. Thanks. Natural selection doesn't exactly sound like the kind of mechanism that would result in a lot of cooperation and snugly social behavior. Let's imagine it. You take variation in some trait, say differences in running speed, and link that trait to survival and reproduction. And so imagine that running speed determines who escapes from predators and then goes on to survive and
have babies. And if that trait is heritable, so if the babies of fast parents are fast themselves, then you have all the ingredients necessary for natural selection. Over time, you'd expect that fast individuals survive and become more common,
while the slow individuals, well, they get eaten. That sounds kind of cutthroat, Yet somehow we've still ended up in a world where animals will call out to warn others of a nearby predator, even if calling out increases the risk that the predator goes after the caller in particular, and honey bees will sting us to protect their hive mates. Even though stinging us will pull out their stinger and effectively disembowel the bee. They give their lives to protect
their buddies living inside the hive. So how did this seemingly brutal mechanism give rise to so much cooperation and helpful behavior. That's what we're going to talk about today. Welcome to Daniel and Kelly's surprisingly cooperative universe.
Hi.
I'm Daniel. I'm a particle physicist, and I think people are the most interesting thing in the universe and also the most terrifying.
Oh hello, I'm Kelly. I study parasites and space and I completely agree with Daniel's assessment, and at the end of this episode when I describe human behavior, I will try not to cry.
So my question for you today, Kelly is do you consider yourself an introvert or an extrovert? And when did you know?
Oh? Yeah, definitely an introvert. I think I hide it well, but I very much enjoy hanging out with people. But at the end of like a conference or something, I will crawl into my bed and like just be absolutely exhausted. And I get very nervous when I go in a room and I have to like pick a group to go hang out with because I assume that nobody really wants to talk to me, And so I love situations where people come up to talk to me because then
I don't feel like I'm putting anyone out. So if you ever see me somewhere, feel free to come up and talk to me, because that relieves the pressure on me and makes me feel so much better. And I don't know when I realized that. I think it was probably in undergrad when I had to like start meeting people. Yeah, I guess I don't know what about you.
I'm not sure how I would classify myself, because on one hand, I feel the same way at the end of a lot of socializing that like at a conference when it was like, hey, let's go out to dinner and I'm like, no, thank you. But also I find that people are my best source of energy, you know, if I go and teach in the classroom. I love that engagement and the response. I love getting emails from listeners.
I love hanging out with friends, Like moments laughing with your friends are more enjoyable than anything you could ever do by yourself. Yeah, and so people are like the greatest mystery and source of joy and happiness in the universe. And also they are completely exhausting.
Yeah.
So I'm not sure where that puts me on the spectrum.
Maybe we're exo introverts intro exoverts. Because I agree, I like, I also really look forward to going to conferences because I cannot wait to see the people at conferences and hear about how they were doing and laugh about stuff and find out if they purposefully infected themselves with any parasites in the last year, and you know, all that stuff. But you know, on the other hand, at the end of the day, I am also like.
I need to see Yeah, exactly. Well, today we are not just telling personnel stories. We are talking about the larger question of human being behavior. Why do people act the way they do? Is it driven by evolution or something else? Even weirder, and today's episode is inspired by a question we got from an eleven year.
Old, didn't we Actually they're thirteen years old now and they are the child of some friends of mine, and I was super excited to get their questions. So let's go ahead and listen to it.
Hi, Daniel and Kelly, I love your podcast, And I have a question why did humans evolve to be social? And why do we go crazy if we're isolated for too long? I also want to know what happened at the human related it's whole life without having contact with other humans, and why could some animals like whales go for so long without having contact with other whales but humans can, thanks, all right?
So on one hand, this is a really fun question, but also a really deep question about evolution, because like the whole foundation of modern biology is evolution and natural selection, and things are the way they are because of this process, and that forces us to think about everything we see through that lens. But it can sometimes be hard to understand how something evolved to exist. You know, you have the examples of the eye and stuff, but human behavior
is a great example. So tell us, Kelly, how do you interpret this question.
Well, I'll be honest, I kind of put this question off for a while because I was like, Okay, I'm going to I'll look it up real quick and see, like, you know, what are people saying these days? And generally the answer I found was, oh, well, humans are social because it benefited us in our evolutionary past. And I was like, yeah, okay, well yeah, but how and like there's got to be a richer answer to that. But
there was generally not a much richer answer. And I think at the end of the day, it's hard to know for a particular species why a behavior arose, in part because behaviors don't leave fossils. But at the end, I'm going to try to give a much better answer. But I thought that we could start by taking a look at why we think we see cooperation and social behavior in general in animals at all, because actually that's a little bit of a Darwinian puzzle.
Yeah, I agree, it's really a fascinating question. On one hand, it seems like maybe it's simple because people learn to cooperate because that's more effective. But if everybody else is cooperating, then like the one jerk who's like lazy and then just steals the results of the mammoth hunt is going to benefit. So it's not obvious why cooperation is always a successful strategy. That's how you have to think about.
It, right, yeah, right, exactly. So in order for natural selection to happen, you have to have variation in a trait. So, for example, maybe you have variation in speediness, and then that variation needs to be important for survival and reproduction.
So maybe the faster individuals are able to run away from the predator and then they survive to reproduce, right, and that trait needs to be passed from parents to offspring, So the faster parents makes faster offspring, and over time you end up with faster individuals in the population, and the genes that produce faster individuals become more common in the population. And that doesn't necessarily sound like a mechanism that would result in more like hugs and cooperation. That
seems like a bit of a cutthroat thing. You know, if you are faster and better able to get away from the predators, are better able to secure the food, then you're the one who gets to reproduce and you're the one who, you know, gets to pass your genes to the next generation. But when when look out in nature we see tons of cooperation. So you know, for example, honey bees, if you walk up to a honeybee nest okay, and you disturb the nest, do not recommend a honey
bee will come out and they'll sting you. And they've got these barbed stingers that get stuck in your skin, and so the stinger will stay behind and the venom gland and like the insides of the honey bee will get pulled out of the bee. The bee will get disemboweled and will die to protect its hive mates. And so that bee is giving its life to protect the
rest of the hive. And we see ants that are willing to, for example, like plug the whole of a nest overnight, even though the temperature is going to kill them overnight. They give their lives to like protect the temperature for the rest of their hivemates. And we see just loads of examples of animals dying for you know, their buddies, and you know, why does that happen?
And so this is a great analogy, for example, to like soldiers dying in a war. Right, they're not going to be around to experience the benefits of victory, and yet they give up their lives. But then it's always easier to understand these things in terms of like ants and bees because you can actually do experiments on them ethically. Right, Yes, so what do we know about why honey bees act altruistically?
Is it because they have like more sophisticated genetic relationships among themselves and with their queens or what's the story?
Yes, absolutely so that is part of it. But first I want to dig down a little bit more and clarify what level we think evolution is happening at. Evolution at the end of the day, is just changes in gene frequencies over time. So when we were talking about natural selection happening for fastness, like being able to run away from the predators, evolution happening there, you'd end up with a higher frequency of the types of genes that
are associated with moving quickly. So over time, the versions of the genes for slow individuals go away and you get more of the versions of the genes for fast individuals. Does that make sense?
It does make sense, But it sounds like you're choosing this set of words gene frequencies changing over time through natural selection very specifically, maybe in contrast to something you imagine is in the minds of the listeners or a general misunderstanding of evolution. What are you contrasting this with, Well.
So I'm eventually going to make the point that individuals are the ones who are carrying these genes around, and selection is going to be happening at the level of individuals and not the level of groups.
I see. So it's not like evolution is this like mastermind guiding some species towards some predetermined goal or something. It's just a bunch of individuals changing over time.
Yeah, it's a frequency of genes that are found in a population, and those genes are carried by individuals that some of which will die and some of which will not. All right, yeah, okay, so individuals are carrying around these genes. And then in the nineteen sixties there was this guy, when Edwards, who was arguing that selection might be happening at the level of like groups, or maybe even at
the level of species, and this idea kind of makes sense. So, like, you know, you look around and there's for example, maybe rodents having two babies each, and you might say, oh, okay, two babies, that's not a lot of babies. Maybe what they're doing is they're trying to not eat all of the seeds. They're trying to make sure that they don't over exploit the seeds for the good of the species. They want to make sure that they're able to survive for many generations.
What considerate and well organized rote.
Yes, yes, you know, maybe we should take some lessons from their behavior, but unfortunately it turns out that we don't actually usually see group selection being a good explanation for what animals are doing in the wild. So imagine you did have like a population of individuals who were very responsible rodents and were limiting themselves to two babies each because they didn't want to over exploit the seeds. And then you had a mutation in a gene, and
a selfish gene popped up. Okay, and those parents six babies. The jerk rats had six babies, and there's all these extra seeds because everybody else is being responsible, and so all of their babies survive. And they also got the jerk gene, and so they have six babies too.
Dominion of the jerk rats.
Dominion of the jerk rats exactly. So over time, that selfish gene is going to pass through the population. You're going to end up with a lot more of this jerk gene.
So does this argue against when Edward's idea of evolution at the population level.
Yes, it does. And so just about whenever we look when we go out into nature, we see that animals are trying to have as many babies as they can, maybe not in a particular season, but across their entire lifetime. We don't see much evidence of individuals sort of doing things for the good of the species. Most of the evidence we find is that they're doing it for the
good of themselves. And we think that's because selfish strategies could easily invade populations where everyone's you know, trying to do things for the good of the species. That's just a strategy that's very easy to invade by more selfish behaviors.
This is a cool test because the cooperative strategy is actually more successful. Right, if nobody's a jerk, everybody does better. It's sort of a prisoner's dilemma situation. But if everybody else is cooperating and you're the jerk, then you individually win out and then your babies dominate the future. Yes, and so if you were operating at a population level, you would definitely choose no jerks.
Yeah.
Yeah.
If selection was acting at the level of the group, then maybe that would be better for everybody, but we don't see evidence of that happening. And additionally, like even if you could get a group of individuals to be like super nice and everybody cooperates, usually we see migration between groups because they don't usually exist completely in isolation. So if you had a jerk group, you know, a little north of you, some jerks might move south and
invade your population. And since you've left all these resources unexploited, they're going to come in and sort of mess everything up for everybody else.
Those northern jerks.
Every time time I know, I'm looking at you, Canada, I'm just kidding. Canadians are way nicer. We should have done it in reverse.
Oh, now you're offending the Mexicans.
Oh no, no, no, I meant it's the Americans ruining things for the Canadians, is what I was saying. No, no, no, no, don't get me wrong. Okay, So there are some arguments still that there could be some situations where it makes sense to think about selection from a group or a species level, But I think in general, we think that most of the time selection is happening at the level of the individual and that you can, you know, get away with not thinking about group selection most of the time.
And this is true for behavior and also for more like mechanical traits like cheetah's running fast and stuff.
Yes, okay, okay, And actually I bought a recent animal behavior textbook because that's what I learned in like the early two thousands, and I was like, I just want to be one hundred percent chore that this is what everybody still says and it is.
So then you're telling me that you can't choose behavior based at the population level, like hey, everybody be nice or everybody like to have go to parties or whatever. And so in that case, how do we get things like altruism or social behavior if natural selection acts only on individuals.
That's the puzzle, right, Yeah, that is the puzzle. Okay. So we're going to talk about three or four different ways that we think you can get it by individual level selection. Oh all right, So the first way is what we call kin selection. This is an idea by
William Hamilton. It was proposed in the sixties, and the idea is that you've got genes for particular traits, and you can get those genes passed from one generation to another by having your own babies directly, but you can also increase the frequency of those genes by doing things like helping out your brother, and so that indirectly increases your fitness because you probably share about fifty percent of your genes by descent because you come from the same parents.
And you know, for example, if you're a diploid organism, so humans are diploid organisms, that means we have two chromosomes. We got fifty percent of our genes from our mom, fifty percent of our genes from our dad, and just by random chance, you and a sibling probably share about fifty percent of the versions of the genes that you have in your body. Does that make sense?
Yes, So basically, I have a big nose. My brother is a big nose. If I help my brother's kids, then I'm increasing the big nose fraction of future generation. So I'm not really being altruistic by helping people who are not my direct offspring.
As long as they're related to you. Yeah, yes, right right, yeah, as long as they're related.
That's why it's called kin selection.
I guess, yes, exactly right, and so are there's some predictions that come from this. You should care about how closely related people are to you, and so for example, you should be more likely to help a brother or a sister, and you should be, you know, sort of willing to help like a half sibling or a cousin.
Depends how big their nose is.
Actually that's maybe, that's right. Depends on the gene. But you know, for example, if you imagine that there is a gene out there for altruism, and that gene does make you more likely to help out other members of your family, then you can imagine that that gene would pass through a population if family members are helping each other. And so there's this fameless quote by a scientist named JBS Haldane and he was asked, would you save a
drowning brother if it risked your own life? And he said no, but I would save two brothers or eight cousins because.
And mathematically that checks out.
That's right, that's right. And so whether or not you should engage in a behavior that helps out your family members to some extent depends on how closely related they are to you. How much the cost would be to yourself and how much they would benefit. And so you should expect to see altruistic behaviors arising a mon closely related individuals if it's going to result in, for example, your siblings having more kids that are going to carry some of the genes that you would find in yourself.
And so maybe you're not having as many kids personally, but if your siblings are having loads of additional kids, then your genes are still getting out there, and so indirectly, your fitness is doing great, and so maybe we see altruism happening because selfishly, that still helps your genes pass through the environment.
All right, So just to make sure I understand, we started out wondering why would anybody die for other members of the population, And this seems like to me a partial answer, because it doesn't suggest you would die for any member of the population, but it tells you that you might sacrifice yourself for people you're related to who are not directly your offspring. Yes, exactly, And that to me described as sort of like limited local altruism that like falls off with the size of the nose of
people in your family. But then you added this twist about a gene for altruism itself, right, because this doesn't require a gene for altruism. You just support people who have enough genes that overlap with you.
Yes, but you could imagine that a gene for altruism would be how you get this trait to pass from family member to family member to family member.
Oh, I see, yeah, The gene for altruism helps you recognize that this is beneficial.
It helps make sure that the trait passes in families and is maintained.
I see, all right.
And we have some examples of this. So, for example, there are these squirrels that you find in California building's ground squirrels, and the females tend to stay in the areas where they were born, whereas the males tend to go away. And so if you're a female, your sisters are likely to be nearby, your aunts are likely to be nearby. And what they find is that the females are more likely to call when there's a predator around.
And so when a predator's around, they call, and then their sisters and their aunts, maybe their mom and even their kids go and hide in their burrows. But when you call, you also increase the probability that the coyote goes after you because you've drawn its attention. So it's a risky behavior that has a cost. But they've also found that females will call even if none of their own kids are around, so it's not just a direct
fitness thing. They will call to help their aunts get out of the way or some or their sisters get out of the way. So it looks like they're also willing to take a cost to get an indirect fitness benefit, so to help their sisters and stuff.
So females without any kids of their own still raise the alarm, putting themselves at risk even though they have no offspring. That's fascinating. Are squirrels smart enough to do this calculation of the little jbs haldines adding up like you know, fractions and cousins and stuff.
Yeah, that's a great question. So I think they really just need to know, like, Okay, I was raised with uh, so you know, for example, they were raised in a nest with their sisters, and so they don't necessarily have to be like, all right, I've got three sisters out here, I'm fifty percent related to all of them. So that's point five plus point five plus point five, that's one point five. So that's more than just me. So you know,
they don't necessarily have to do those calculations. They just have to, like, you know, have some affiliative feeling for the individuals that they were raised in a nest with and be willing to call. And so maybe the genes
that are being passed aren't necessarily like altruism genes. They're just genes for you know, having like a nice feeling about the people that you were raised in a nest or you know, the squirrels you were raised in a nest with and being willing to call if you think that they're in danger.
Or does it work even if it's more instinctive, like if every female squirrel responds to a predator with a call, than in general that increases the fitness and the whole population, including their own, and then that gene tends to survive.
Is that a reasonable argument, Well, there is evidence that females are less likely to call if they are surrounded by females they are not related to. Oh wow, so they will withhold calling when they're not around family members.
So it's really context dependent. They are doing fractions in their head. When deciding whether to save your.
Life, they are at least deciding are there people who were at the last family reunion or not?
What did they bring to the pot luck?
That's right, that's right. And if you didn't bring enough, I'm not gonna call that coyote, can have you for dinner.
I know that akon casserole didn't pass muster, and so I'm sorry.
Okay, let's take a break, and when we get back, we're going to return to the honey bees and the insects that Daniel asked about like fifteen minutes ago. And I was like, oh, get right back to it, and then I didn't.
All right, we're back, and we're answering a question from a listener about how behaviors can evolve and a broader question about altruism in evolution. So tell me about insects. Why do bees give up their lives for their fellow bees?
Yeah, so, in particular, we're talking about hymenopteran insects, and hymenoptrans are like the bees and the ants and stuff like that, and the wasps and these have some of the most amazing examples of hymenopterans. Oh yeah, you'd ask that.
Well, it's just it has an interesting prefix.
So hymen is Greek for membrane and turin is wing, and so they have wing membranes.
Got it. Okay, Yeah, so membrane. That's a great answer.
Yeah, thanks. Okay. So they have a really interesting sort of system for determining whether or not they end up being males or females. And we talked about this a little bit in the Listener Questions episode. But briefly, males are haploid, which means they only get one set of genetic information, so they develop from unfertilized eggs. So females will not mate with males, they'll just lay an egg. It will have one set of chromosomes instead of two,
whereas females will get two sets of chromosomes. And so when a daughter is born, she gets one hundred percent of the info from dad because you only had one set of chromosomes to give. So all of the sisters they're going to get the same chromosome from Dad, So that chromosome's one hundred percent the same the chromosome they get from mom. They're going to have a like fifty percent chance of having the same information if you're comparing
between two sisters. So if you look at two sisters, seventy five percent of their genetic information is going to be the same.
Whereas between me and my brothers and humans it's only fifty percent.
That's right, I see. And if you compare the mom to her daughters, they're only fifty percent similar. And so the daughters are like super hyper similar to each other.
They're more like clones than our sisters.
Yeah, yeah, they're much closer. And so you find that they're willing to help their mom produce a bunch of additional sisters because they're producing more individuals that are very similar to each other, and they are quite willing to give up their lives to protect each other because they
are very genetically similar. And so we think that that's why you tend to see these amazing examples of animals being willing to give up their lives to protect each other because in these systems, at least the sisters tend to be very genetically similar. So kin selection seems to be able to particularly work well in these systems.
It's fascinating that behavior seems to follow these relationships. You know that people who are more closely aligned tend to act in a way that benefits people who are more related to them. And isn't it because selection at the level of individuals, when individuals have these complex overlaps, tends to benefit behaviors that leads to the selection of those genes that led to those behaviors. Is that right?
When you are closely related to individuals, you might be more likely to see a benefit to any genes associated with behaviors for cooperation.
But you have to see the benefit. I guess that's my question, you know, because like we were talking earlier about like the squirrels knowing whether their people are related, But in the case of like a bee, like a bee isn't aware that they're related in some way? Isn't it just that their behavior benefits people who are more closely related to them without them being aware of their like sisterly relationship? I mean, are bees feeling a sisterly bond with their clone sisters?
I see? Okay, So I think ants are able to tell the difference between nestmates and not nestmates based on their chemical smell. I wouldn't be surprised if bees could do something similar. There are social trematodes We talked about this in a prior episode, Living in the go nedes of snails that are able to tell the difference between members of the same species that are a different genotype that are trying to invade and take over the snail.
And so I think even for species that we think of as like you know, quite quote unquote lower, they are able to tell even within the same species, you know, are you my family or not? Which is kind of amazing. But I think there are a lot of techniques for telling, even in a hive, are you in my family or are you not in my family?
Yeah? I see, And that makes sense because if you can do that, then you can act differently based on that information. And that also will help propagate your genes if you help people who have your genes more than you help people who don't have your genes. Yes, yeah, that makes sense.
Yeah, I think being able to recognize family is a big part of how this stuff works.
All right. Cool, So in the future when the aliens come and they create like an army of ten thousand Daniel clones, I will just like naturally help those guys out more than like all the Kelly clones, because I'll know that I'm more closely related to the damn clones, and it's just nature. Kelly, don't be offended.
Okay, okay, but let's move on to mechanism too, which is mutualism, which is there are some instances where there is mutual benefit to working together and you both get higher fitness by cooperating. And so, for example, although I was going to say, you know, we both have this great fitness together, but I don't think it's going to help either of our reproductions. So maybe that's not going to work. You help the Daniel clones, I understand. So all right, So here here's an example in paper wasps.
You may have seen like these giant wasp nests that kind of look like they're made of paper, Like you know, they're literally using their mouth parts to sort of scrape parts off of trees or parts off of your furniture, and then they make these giant nests. They're made by several females, and some of those females, up to thirty
five percent are actually not related. And so why would they be helping to make these giant nests if they're not related, Because only one of the females in that nest is laying the eggs, and everybody else is subordinating themselves and choosing to not lay eggs. Yeah, and so why would they do that, Well, it turns out that at some point the dominant female will die and one of the subordinate females will get the chance to take
over that giant nest when she dies. And the giant nests have a much better chance of surviving like a predator attack than teeny tiny nests that are made by solitary females. So there are nests like that are made by solitary females who try to go it alone. And so there are some females who will say, all right, you know what, I'm not related to you, but I am going to help you out in the hope that maybe one day I'm going to get to take over
this giant kingdom and my turn will come. And so I'm going to cooperate now in the hope that later I'm going to get to take this over. And so it's like a delayed benefit with it. This is called postponed coordination. And actually this idea of like territorial inheritance, where if I help you now, I might get to take over this amazing territory later is a pretty common thing that we see in like birds and insects and lots of other lots of other species.
Okay, so then my question here is it makes sense to cooperate. Everybody benefits. But what about the prisoner's dilima example we talked about earlier. Why aren't there jerk wasps who come and wait for you to build your nice nest and then say, oh, wouldn't it be a tragedy if something were to happen to your paper wasp nest and you know, kill everybody and take it over.
Ah. Yeah, So usually the individuals who are helping are weaker and couldn't be the dominant individual for whatever reason. And so, for example, if you are one of the thirty five percent of individuals who are not genetically related to the dominant individual who's making the nest, you probably couldn't try to oust the dominant individual who's laying the eggs. You'd probably get slaughtered if you tried to do that.
And so I think in a lot of cases you would be outnumbered, and you are kind of like waiting to get older, and in the meantime, you're probably also like learning how things are done. It's also like an apprenticeship, and so I think that if you could go it alone, maybe you would, but you're just sort of waiting for your chance.
I see, all right, cool, so that makes.
Sense, okay, And then option three is manipulation. So maybe it looks like cooperation, but you are just straight up being coerced. And you should go to our episode on interspecific brood parasitism where we talk about birds who take care of eggs that are not theirs because they were tricked into doing so.
So definitely not altruism, right.
Definitely, just you have straight up been duped. And so last let's talk about reciprocity. This used to be called reciprocal altruism, but we stop calling it that because altruism, in my mind, is when you do something nice with no anti a patient that you'll get paid back. But this is really like you're doing something nice because you expect to get paid back eventually.
This is like a gift exchange.
Yeah right, yeah, that doesn't really feel like ultruism, So we call it reciprocity. And my favorite example of reciprocity is vampire bats in Costa Rica. So the idea here is that you are doing something nice because you expect that you're going to interact with this individual over and over and over again. So you mentioned the prisoner's dilemma, and so the prisoner's dilemma is a game that is
often used to think about these reciprocal interactions. And it doesn't work if you're only going to interact with somebody once. If you interact with someone once, you should probably dupe them to try to get, you know, the best outcome
from the interaction for that one iteration. But if you're going to interact with someone over and over and over and over again, maybe it makes sense to cooperate and try to make it so that both of you are getting the best outcome from interacting over and over and over again.
And I remember they did this experiment and they showed that like the best strategy for the prisoners to dumble is called like tit for tat. Basically, people are being nice to you, you're nice to them. People are not nice to you. You're not nice back.
Right.
Excelelrod is the one who's set up I think the games and people could submit different strategies and tit for tat one.
Right, Okay, classic game theory. Cool stuff.
All right, So with these vampire bats that live in Costa Rica, they go out for a blood meal at night. If they unfortunately don't get a blood meal, they can make it for one night, but if they don't get a blood meal for three nights in a row, they're probably gonna die. But if they get a blood meal and they could find an animal, they probably get more than enough blood and they could afford to share some.
So helping out a roost meat so they live in roosts, isn't a big cost to you, but could be a big benefit to an individual who didn't get any food that night.
How do they help them out? They're like, spit up some blood.
Yeah, yeah, they puke in their mouth. Yeah, super gross. Puke up blood in their mouth?
You very much?
Yeah, well you know, yeah, well you wanted to do a podcast with an animal behavior person, this is what you get. So anyway, Okay, So they looked and they saw that bats that didn't manage to get a meal for the night, they weren't very likely to get fed by family members. So that's totally consistent with our kin selection discussion. But they were also really likely to get
fed by roostmates. So there was a guy who went out and they collected a bunch of bats from the wild, brought them into the lab and then held onto some of the bats and made it so that they couldn't get food, and then they released them back into a room that had some individuals from the same roost and some individuals that were completely new to the bats, so they essentially had like friends and non friends, and the friends were much more likely to feed the bats when
it went in asking for food and essentially was like, I'm hungry, and individuals that knew the bat were like, okay, I'll feed you bat, And so it does seem like having some familiarity with an individual and essentially like some anticipation that you'll see this individual again so they might be able to pay you back. Yeah, made you more
likely to feed them. And individuals who were fed were then more likely to feed individuals later on in the experiment, And so it does look like other individuals expect you to ante up later if it's known that you were helped out, and if you see someone pretty often, then
you feel like you can ask them for help. And so it does look like these bats have this reciprocal altruism system going on, where if you've got these iterated interactions where you know you're going to see them pretty often, you can ask them for help and expect to get help in return.
I see, all right, So that's like another reason why what seems like altruistic behavior might benefit the individual, And that seems to be the common thread is that you're arguing that all of this behavior, which seems like it might have been selected at the group level, can sometimes be explained by evolution on the individual because in the end, all of this behavior really does come back to benefit the individual, and that's why it would.
Be selected exactly. Yep, that's the perfect way. At bottom line it whenever we've seen examples of cooperation, we've been able to find explanations that can be explained by individual level selection, don't require group selection, and can be completely understood through the lens of natural selection.
So everybody out there is selfish, you're.
Saying, well, we do see a lot of selfish behavior in nature. We also, this is kind of interesting. We don't see a lot of examples of spite, which is where someone is willing, which is where someone is willing to accept a negative impact on themselves just to see something bad happen as someone else. But we do see humans do that. That's a unique thing.
Now, this sounds like a Mary roach book spite. Spite examples of people hurting themselves just to get back at somebody.
Else we know of at least one case. So like, there's been studies on monkeys in the lab, capuchin monkeys, I think, where if a capuchin monkey was observed getting too many of the most delicious snack, another monkey would take a less delicious snack as long as it meant the other monkey would get punished in some way like no, no, you've been getting too many good snacks. This is not cool. You're getting punished and I'm getting punished. I don't care,
it's not cool. So other animals are capable of spite.
I'm willing to have a less delicious snack as long as I get to see you suffer.
That's right.
Wow, that is cold cold.
Yeah, So we don't see it as often as we see humans doing it, but we also see amazing examples of cooperation and social behavior in humans, which gets to Kurran's question, which we will get to after the break.
All right, we're back when we're taking a long detour to answer this question, first giving you a background and how evolution works, and reminding you that there is no true altruism out there in the animal kingdom, and that in the end, it all benefits the individual and that's how evolution works. So tell us, Kelly, how does this help us understand the answer to Karen's question about human behavior?
All right, Well, first of all, I'm hoping this wasn't too painful for Karen. They have professor parents, so hopefully they're accustomed to long winded answers and so they're not surprised.
I'm afraid you might be making the wrong assumption there. Now. My daughter Hazel is like oversensitized to long answers. If she sends us when coming, she's like, I didn't ask for a college lecture.
All right, well, I'll tell them that they can fast forward to forty minutes in and get right to the point. Okay, so let's hone in on mammals, and so you'll see I actually haven't quite gotten the answer. We're just getting to mammals. So all right, two thirds of mammals are
actually living alone. So only of mammals are social. In other cases, they get together to mate and then they tend to split up, and the females will spend some time with the babies because mammals do lactation, which means the moms need to be around the babies for a while to feed them. But okay, so now, why did
humans in particular evolve to be social? Yeaht hey, they're extraordinaries. Well, Daniel and I actually recorded an answer to the question that I just asked, but after I listened to our answer, I decided it's like not a super satisfying answer. So instead I reached out to an expert to get away better answer, and I'm having our amazing audio guy Matt,
drop that much better answer in here. Doctor Nathan Lynz is a professor of biology at John Jay College, City University of New York, and he's the author of three
books that touch on human evolution topics. We had him on the show on February twenty seventh, twenty tw to talk about the sexual evolution How five hundred million years of sex, gender, and mating shape modern relationships, which is a book you all should definitely check out, and you can also find more of his writing over at the Human Evolution Blog and today we're bringing him on to answer one of Karen's questions. And so, Nathan, welcome back on to the show.
It's a pleasure. I love this podcast.
Well, we love having you on the show. This is your third appearance now, which I think makes you tied with Scott Solomon for most regular appearances on the show. So that's awesome for us.
The gauntlet has been thrown down.
That's right, that's right. Yeah, So folks submit more human evolution questions and then we can you know, we can get Nathan on even more.
So.
Yeah, So why did humans evolve to be social? And a little bit of context here. We just spent forty minutes talking about social evolution and other animals. We've talked about kin selection, reciprocal altruism, and now we're talking about humans. Why do we cooperate and why? Why are we social? What do we know about this?
Yeah?
So, I mean humans, So mammals and then primates evolved to be very very social. Very few mammals live solitary lives. They live in communities, they live in families, and they interact with one another and they're obviously they're better off when they do. So humans have taken this to an incredible extreme. And the reason why is humans are the ultimate generalists, right, We're actually not particularly well evolved or suited for any particular habitat or lifestyle. Instead, we went
the other way. We evolved to be adaptable and to live in a whole variety of ways.
So, you know, there are animals.
That can throw better, that can run faster, that can climb better, that can swim better. But we can run and climb and jump, and we could do it all, and we can eat a variety of diets. Think of how different world diets are around the world, you know, from chore lines and seafaring peoples to desert people to tundra to rainforest. So that that quality of being very general in our approach lends itself to division of labor where individuals do not have to all do.
The same thing.
Whereas most other animals they all do the same thing. They can do different things, and they can work together. But there's not like trades, you know, there aren't professions. They all basically do the same thing, and they basically all have to learn everything they need to know each generation. Right, they don't inherit a whole bunch of knowledge. They do learn from each other, but they don't intentionally teach anything.
And that's what humans do is we have this huge toolkit of knowledge, of cultural knowledge that gets passed on each generation and then get specialized. So some individuals can do one thing. They can be homesteaders, you know, they can work with their hands. Other people are out hunting
and they have great vision, whatever it is. There's lots of different ways that you can contribute to the group and be important and valuable, and therefore your genes are more likely to find success, not because you're good at this one specific thing, but because you're good at something.
So we were all contributing in this wide variety of ways. Well, that creates a social network that is better the larger it gets, because then that's how you add more and more skills to the toolkit, is that any one person doesn't have to do it all. They only have to do one thing. And so our groups became highly intricate, highly cooperative, and also large reservoirs of knowledge.
And the best support for this hypothesis is that the few examples we have of population declines where you get a bottleneck, they lose tons of skills. So we have societies like in Tasmania where we can tell from the fossils and the archaeology that they used to be able to do some things that they no longer can. I mean now they can, but when they were first kind of studied anthropologically, they had actually lost a lot of cultural knowledge when the population shrunk to a small size.
So our large groups with intricate social structures.
And division of labor, that created a society that was much better than just the sum of its parts. Right, we're not all doing the same thing, we're contributing to this larger group set.
So that's why social evolution just really ran out of control.
And in fact, it's what Dan Lieberman calls evolution in warp drive because you don't have to wait around for new genes or new alleles, you know, mutations to provide things. You can actually learn a new skill, teach it, and then boom, everyone has it. So it's really our sociality is key to our success.
Why just us? Why don't more animals do this generalist thing that has clearly been so great for us?
Well, to be honest, it's an unlikely scenario to play out because if you think about it. Selection generally operates on the level of the individual, right, so you don't get anything out of helping other people, for example, it doesn't unless it directly benefits you.
It won't. Those genes won't persist.
And in fact, I just finished a book not too long called The Accidental Homo Sapiens, and it talks about how, in many ways our particular trajectory was not destined for success. It's actually quite costly to be have these big, huge brains at the expense of our bodies. We use our brains instead of our bodies, and so our bodies actually aren't that great.
I read a book about that.
Because we rely on our on our brains so much, our bodies kind of aren't as heavily scrutinized by natural selection.
That book is called Human Errors. Right, Yes, another great book.
Thanks for the plug. It's available at fine stores near you.
Yeah, don't miss those opportunities.
But the best proof of the sort of futility of our approach is if you look at all of our close relatives. They all went extinct, right and everywhere, whether it's Homo erectus or you know, Homo habilists, and you know, total rid of fences. Think of all of the named species, those were all the smartest things that they were planet had ever seen, and they all went extinct, right, some of them because of direct interaction with us, but most of them probably not. You know, so this is not
actually that successful a strategy. And our own species was kind of on the nice edge of extinction multiple.
Times in our history.
Right.
We have a lot of population bottlenecks in our genetic history.
So what that means is it's a great system.
Once you get big enough and spread around far enough, then it's a great system. But until then, favoring the development of the brain over everything else was a recipe for extinction.
How sure are we of this hypothesis? This seems like a hard thing. You know, studying behavior is tough because behavior rarely leaves fossils, Like, you know, what percent confidence would you put on this explanation for why we're social?
I don't know. It's really hard to say. What we can do.
The best way to test these is to look at animal correlates and to look at closely related species that have some key difference and kind of see how it plays out. And you know, for example, if you look at chimpanzees and bonobos. They're very closely related. They're sister species, separated by about a million and a half year of distinct evolution, and their sociality is very very different, and a very short amount of time they developed very different
social structures. The bonobo seems to be a bit more cooperative and egalitarian and gregarious. You know, they still have some you know, competition and it can be ruthless, but in general they're more pro social than the chimpanzees, which are much more aggressive and hierarchical. But the common chipanzees are more successful if you use numbers as your outfit, so it's you know, our sociality, it was no guarantee of success. So we don't really know. A lot of social evolution.
Is speculative, but you know, when these hypotheses attract a lot of attention and a lot of scrutiny, and you have a lot of scientists who, you know, would try to think of clever ways to test them.
So all we can do is say that this explanation.
Has so far held up and no a lot without a time machine, we don't really know for sure. As you said, behaviors don't fossilize, but archaeology does, and we have a lot of evidence of an intricately pro social ancestry. I mean, they're they're. My favorite fossil of all time is called the old Man from Demonissi. He's it's a fossil of a homoerectus from about two and a half
million years ago. And this is an old man who lost all of his teeth and survived because we can tell by the healing of his bones that he survived for at least two years beyond having any teeth in his head. How does one survive before you know, soft cooked foods, you know, the only explanation is that somebody was chewing his food for him, someone was preparing his food, softening it. And why would you do this to this old man who was a burden to his group because he knew things.
Or maybe he was really fun to have around.
Yeah, he made him laugh, you know, But the point is he contributed, like and that's I think, as far as I know, the oldest evidence we have that that just being older, you know, was a value to the group because you old people know things, you know, they've been.
Around longer, they teach things, and so when and by the way, that fossil does not stand alone. We have a lot of other examples of clearly individuals that had been helped by their group that by having all kinds of you know, injuries and deformities and yet continue to live for years on end, they couldn't have done that without help. So we've been caring for each other, taking care of each other, and also respecting each other's contributions.
We've been doing that for a very, very long time, and I'm pretty convinced that that's that our sociality is the key the key aspect.
What do you think is the sort of leading alternative hypothesis.
Well, there's a lot of people still to this day who have a hard time accepting any benefits to the group that a particular you know, genetic trade, certain adaptation would have because if it doesn't directly benefit the individual and quickly, some biologists, many biologists, can't see a way that it would.
Be selected for.
I'm not convinced of that. I think that the tide is turning against the opponents of group selection. The reason why is it's not hard to imagine when you have multiple groups competing against each other that a cooperative group would outcompete a non cooperative.
Or less cooperative group.
And this is the work of Davis Loan Wilson, and he's been ringing this bell for fifty years. And the idea is that it's true that really competitive, kind of antisocial instincts can be rewarded within a group, rewarded meaning success. But when you have groups competing against each other, that
actually becomes the more powerful selective force. And to be honest, Darwin mentioned this in the Descent of Man when he talked about if you look at any two human groups when they clash, the differences between them that determined which group is successful is never genetic, right, It's always has to do with something entirely non genetic, something social, something cultural,
something technological. And if you can imagine that same competition playing out for millions of years, not just a few generations, but millions of years, what you would see emerging is very cooperative, pro social groups would tend to outcompete those that aren't.
But isn't that social behavior somehow encoded in the gene so indirectly, it is still a genetic advantage.
Right, It is?
It is and so and that's why I think group selection is starting to experience this renaissance where people can recognize that if the genes make you more social than your whole group really is better. And if your group is competing against the less one than those genes would accumulate. You know, the jury still out on a lot of
these a lot of these questions. But one thing I would point out is that competition and cooperation we think of them as opposites, but actually they involve all of the same skill sets, right, because to cooperate with someone requires the same things to compete against them, you have to understand them. You have to be able to predict their behavior, you have to be able to manipulate them. And whether that's good or bad, you know, depending on
who it is. But you know, if you can kind of get someone to do what you want, you have to understand them. So it's like empathy, and I mean that is like emotional empathy, cognitive empathy. And when you have that ability, you can either work with them or work against them. So it's the same skill set. So what the difference is who do you identify as groups? So what makes you cooperative versus competitive is in group versus outgroup identification, which to me still proves the point
that you had cooperative groups competing against each other. Cooperation and competition do exist together at the same time in the same individuals, and that's why you can have someone who's you know, extremely you know, generous and nice to his friends and absolutely ruthless to his enemies. I mean the classic caces that Nazi soldiers used to come home and kiss their children gently on the head, you know, Like we're all capable of both evil and pro social acts.
Even on a dying we can switch, right, So, because I think it's the same parts of our brain. It's just whether or not we identify as pro social or anti is in group outgroup identification, which is depressing given the way the world is increasingly pitting us against each other.
Agreed, fascinating. Do you think when we meet aliens we will discover the same sort of social structures there, and the same sort of you know, arguments apply.
It's really hard to predict anything about how life outside of you know, the selective pressures of Earth, how that would evolve.
But the arguments you've made are fairly general, right.
Yeah, exactly.
It's very hard to imagine how a very anti social species could ever evolve very far, and we see that in our own planet, right, So there are some creatures who have evolved to be very solitary as adults and are fairly hostile to one another. The orangutan is our closest relative that, at least among the males. They're just generally hostile. They kind of hate each other. So it's
probably a dead end evolutionarily. It's hard to imagine getting much And you know, Tasmanian devils are sort of the same way that they pretty much hate one another.
So we're not going to be visited by space orangutangs, that's your prediction.
Yeah, I think.
I think like if you if you watch Star Trek and and and you know Galaxy, you know all of these, it's hard to imagine the really nasty, anti ruthless ones ever becoming that successful.
But I'm an optimist, so maybe that's where that's coming from. Is I just refuse to believe that evil's gonna win?
But I don't know.
I think that attitude is helpful to keep us all going personal.
Yeah, but even if it's wrong, it's a youthful illusion, right, Yeah.
I mean, you need something to get you up in the morning. And get you out of bed and keep you going personally. Maybe I'm speaking for myself now, but.
Yeah, well, use useful illusions. That's a whole area of evolutionary thought as well. Useful illusions. I mean, free will is very likely a useful illusion.
Even our sense of self as a as a as an identity is a useful consciousness, useful illusion.
Yeah, well, we are getting into a whole new episode there, and we will have you back on to talk about that some other times. So thank you so much for answering that question, and we'll chat with you later. Okay, we're back to our regularly scheduled Daniel and Kelly programming. So Karen also wanted to know why do we go crazy if we're isolated and why doesn't that happen to other species like whales? And so the first thing I do when I have a question like why do we
go crazy? Is first I want to ask do we go crazy? Let's make sure that there's evidence for that statement, and so you know, first of all, I'll note that some of us, there's a lot of variability and how our species responds to social isolation. Some of us really would rather be by ourselves. Yeah, yeah, but for some
of us, loneliness is detrimental to our health. And so according to the Centers for Disease Control, social isolation and loneliness can increase a person's risk for heart disease and stroke, type two diabetes, depression and anxiety, suicidality and self harm, dementia, and earlier death. Yikes. Okay, so lots lots of things. And so why well, you know, we for species that are social, our brains are sort of hardwired to expect
that level of connection. And so when we don't have that connection, when you want that connection, that can be stressful. And so there's evidence that people who are isolated, who are feeling isolated and feeling lonely, they have higher levels of stress hormones. So we have these like hormones that our body releases when we're stressed out and in acute stressors.
So like you know, if you need to run out in front of a car to pull your dog out from you know, the path of the car, having a big release of stress hormones is good because you you know, you run out there quickly, you go back and your body then returns to normal. Like it helps you in that immediate moment. But if you have high levels of stress hormones all the time, that's bad for your body. It does things like mess with your immune system, and if your immune system is messed up, then when you
get sick, you get sick worse. And it can do things like increase your risk of type two diabetes, and over time, it can make you sort of depressed and anxious and stuff like that. And so this can have negative impacts on our bodies, especially if you're feeling isolated for a really long time. So Karen is right, being isolated is definitely bad for your health, but it also is bad for other social animals as well. So any animal that's highly social does show evidence of being harmed,
like physically by being isolated socially. And I don't know about whales in particular, because it's hard to do these kinds of studies on big animals like whales, But there are monkeys that have been in labs and we've infected them with viruses, and if they're socially isolated, they show
similar things that you see in humans. They show high levels of stress hormones, their immune systems don't respond to the virus as well, and so you see more of the virus particles moving around in their body, and they're more likely to die from that viral infection. So very similar to what we were talking about in humans.
That's a terrible experiment. Not only are you making the monkey sick, but then you make them be on their own and see if that makes it even worse.
Yeah, I mean so, there's a really interesting book by Robert Sapolski called Why Zebras Don't Get Ulcers? And this was an example he used in that book. And so you know, monkeys are often used as a way of trying to understand diseases that humans get associated by having chronic stress, and that book is a really interesting look at how chronic stress can impact a lot of different aspects of our lives. But yes, I agree, that's a
horrible experiment. Here's another horrible experiment. Harry Harlowe in the nineteen fifties in the nineteen sixties was living at a time where people were arguing that the main reason babies were attached to their moms is because they're a source of food, and that's it. They're a source of food.
Is the wire monkey experiment?
This does the wire monkey experiment? Oh, my God. And so so he was like, no, it's not just food. It's because there's like there's comfort and love and that and attachment and those things matter too. And so to show that, he took infant reesiss monkeys and he created two kinds of quote unquote moms. Both of them started from a wooden and wire frame, but one of them also had like a rubber or a foam support and
then a terry cloth on top of it. And he alternated which one got a bottle, and so which got a bottle which quote unquote mom, Yeah, got a bottle. And so if like comfort didn't matter, the baby should just stick to the bottle wherever the bottle was. But it turned out if the bottle is on the wire mom, the baby will go over to the wire mom, drink its milk, and then immediately go back to the terry cloth mom for support. So clearly it's more than just
where the bottle is. It wants to feel like the comfort.
And there's something just so sad about how a terry cloth is a stand in for comfort, I know, if not even the presence of another monkey. It's like this thing is so desperate for love that a will find comfort in a towel.
I know, I know. And then they also did experiments where he just kind of put it in a space like without any sort of comfort, and it would sort of stare at the wall and go in circles and just sort of freak out. And then if you would put it and it would hurt itself. And then if you put it in a room with other infant monkeys, eventually it would be totally confused about how to interact with them, and some of them stopped eating and would
pass away. And I should start this episode with a disclaimer anyway, So he did a variety of experiments, and the monkeys that had just the terry cloth were in a much better shape, Like they would go out and explore the environment, and they would like explore the environment and then run back to the terry cloth mom if they got scared, and then they would go back out
and explore again. And the one that didn't have a terry cloth mom in the cage at all would just kind of like sit in a corner, like huddled up,
sucking its thumb, being totally upset. And so anyway, the point is, there are lots of other animals that really need love in social connection as well, and so humans we get totally messed up without it, but so do other animals also, and so any animal that it seems like any animal that's wired to need social connection who misses who doesn't have it, really suffers from that.
This reminds me also of the sort of accidental terrible experiment of the like Eastern European orphanages, where there were a lot of kids that were sort of raised mechanically in cribs and left in their cribs like most of their childhood until there were seven, and then had difficulty forming attachments, right, So I.
Think that was in Romania, Chowchescu outlawed birth control, and so you ended up with a bunch of babies all at once from a bunch of parents that were not quite ready to take care of them. And maybe it wasn't half, but a subset of those children were then given to foster families, and you could compare the outcomes, and the kiddos who ended up in foster families did a lot better. And so yes, there's a lot of
evidence that even just getting hugs makes a huge difference. Okay, And then the last question was what would happen if a human lived its whole life without ever having contact with another human. This is so depressing. This is where we hope that Kelly is not going to cry here. So the answer is nothing good. So for ethical reasons, this is of course an experiment that we can't do.
And any experiments that have happened, you know, quote unquote naturally have had like abuse layered on top of them, so it's not like a clean experiment essentially. So let's see. So there have been like quote unquote feral children that have been like found out in the wilds, that have been raised by animals. And in these cases, these children had to have been at least for a while raised with adults, because you know, they had to have been
born to adults. They had to have been raised up until a point where they could you know, probably walk around.
Wolves can't nurse an infant, for.
Example, They're probably not going to nurse an infant, right and so one, there's a lot of evidence that some of these stories are actually just stories and didn't actually happen. There's also some evidence that some of these are cases of kids that hit age six or seven, their parents identified that the kiddo had a disability, and they decided they were just going to abandon the kid in the woods.
And then the kid was found, you know, months or years later, and the kiddo had difficulty communicating, and it wasn't necessarily clear if that was the disability or if that was the time alone in the woods. And so humans are horrible is really what I conclude from the feral children examples. But in general, if there is a lesson from the federal children's stories, it appears to be
that language is impacted. If there are any cases where children who could have developed language normally were released out into the wild, it seems that their language is impacted and some of their ability to exhibit social behaviors that we've come to expect from kids in society, things like eating with a fork and knowing which behaviors are acceptable when you're in private and which behaviors are acceptable when you are in public, like.
Can you bring up poop at the dinner table? Only if they're biologists.
There ex was Katrina Ferrell.
I'm just saying behavior is surprisingly context.
Depending it is it is okay. And then there are a handful of kids that you'd maybe call cases of isolation where they were kept in houses where they weren't really interacting with people. But again this is isolation layered with abuse, so it's not just isolation. So for example, in the nineteen seventies, there was a kid named Genie who for years was locked in a room by herself, was tied to a toilet, and was abused by her father, and eventually she was found and she had very few words.
She was able to develop some words with a little bit of extra help, but she never was really able to develop grammar. And so grammar seems to be maybe something that we need to develop early if we're going to develop it at all, or it needs to be something that we hear a little bit when we're younger. And she also had some trouble with understanding what was societally acceptable, you know, again, like what is okay to do in public? What is not okay to do in public?
You know, how close is it acceptable to be when you're interacting with someone, stuff like that In general, like I read through a couple cases before I felt like I wasn't going to be able to not cry. And it seemed like in general, language and meeting societal expectations were the things that tended to get impacted most strongly by these isolation things. But again, in all of these cases you also have like abuse layered in, so it's complicated.
Isn't it amazing that you need like a license to drive a car but not to become a parent.
Sometimes I do feel like it is amazing.
Yeah, all right, So bottom line it for us, Kelly, what is the overall answer to Karen's question.
My brain is so mired right now and all of the depressing stuff that we just talked about, I'm gonna try to lift it up a little bit. So our species does some absolutely amazing things socially, you know, so, like we share information with each other that has resulted in our ability to do things like create vaccines. Everybody knows how excited I am about vaccines that like save
the lives of our children. We are able to share technologies that heat our homes and make it so we can live even in Virginia and love Virginia.
And on that point, make jokes which can like bring light to the darkness and make people feel happy and together even if they're something Yeah exactly.
And you know, these these horrible stories of isolation that I read about part of why they're so horrible is because they are really rare. And for example, I live in a place where there's incredible support for you know, for kiddos with disabilities, and there's just you know, incredible school system, and there's just incredible support in general. And so we are a species that in a lot of
cases takes care of each other. I would love to see us make more progress there, but in general, you know, there's a lot to be excited about it.
And so thanks to everybody out there who has a job where you're taking care of people you're not directly related to. Teachers and soldiers and firefighters and everybody out there who's helping make the world a little bit of a better place. Thank you all.
Yeah.
And one of the amazing things about our species is I think that maybe we are the only species where you really see altruism, where you'll see people make a huge donation or something too an organization anonymously, where they really don't expect to get anything in return. And so way to go humans. We're not perfect, but a lot of us do some good stuff.
And for all of these examples of terrible parenting, there are millions and millions of people out there who just love their kiddos to smithereens right.
Oh my gosh, yes, amen, all right.
And we love all of you, and we love all of your questions and your curiosity and your desire to know everything we do and don't know about this amazing, beautiful and crazy universe.
And thank you to Karin for sharing your question with us. I'm sorry it got so dark at the end there. We look forward to hearing what you thought of the answer.
Hi, guys, thanks so much for answer my question. I don't mind the long winded answer, and I thought it was really interesting to take a tour of altruism throughout the animal kingdom. I also thought it was interesting that some animals will be promoting their genes by helping others who are closely related to that. Thanks so much. Bye.
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