Athena (00:03):
Have you been zombified by the apocalypse or thoughts about the apocalypse or fear [Dave agrees, "Oh, yeah."] that the apocalypse is going to happen?

Dave (00:13):
Yeah, definitely. So a lot actually. I think maybe, I don't know if it's too much or just the right amount. We'll see. So how about you?

Athena (00:20):
Yeah. Well I, um, I have been zombified by contemplating how apocalyptic our species is. Like are we actually built for dealing with the apocalypse or not? That's what we talk about today.

Dave (00:40):
Alright. So who are we talking to today?

Athena (00:42):
Welcome to the Zombified Podcast, your source for fresh brains. I'm your host Athena Aktipis, psychology professor at ASU and chair of the Zombie Apocalypse Medicine Alliance.

Dave (00:55):
And I am your co-host, Dave Lundberg-Kenrick, media outreach program manager at ASU and brain enthusiast.

Athena (01:03):
And apocalypse enthusiast!

Dave (01:05):
That's right and fear of the apocalypse enthusiasts! [laughter]

Athena (01:09):
I'm kind of actually into the apocalypse.
Dave (01:12):
Oh, you're like ready for it?

Athena (01:14):
I don't know that I'm ready for it, but it's fun to think about it even though it's also terrifying.

Dave (01:20):
That's true. Actually, now that I think about it, now that I'm thinking about the upside, I think it could be kind of fun! [laughter]

Athena (01:26):
And this episode is really about to what extent have we as humans experienced apocalyptic conditions during our evolutionary history.

Dave (01:37):
Oh, so, so what counts as an apocalyptic condition?

Athena (01:41):
You're going to have to listen to find out!

Dave (01:44):
Who are we talking to today?

Athena (01:44):
Today, we are talking to Mike Gurven who is an anthropologist who studies, among other things, cooperation and the apocalypse. So we have a lot to talk about. Mike and I.

Dave (01:57):
Alright. And what's your, what's your favorite part?

Athena (01:59):
My favorite part of this episode is when Mike explains how he used, uh, math in order to figure out how often humans encountered the apocalypse in our evolutionary history.

Dave (02:15):
Cool. So that's always, always the first thing I think of with the apocalypse is math! [laughter]

Athena (02:21):
So let's hear from this week's fresh brain, Mike Gurven!

Song (02:25):
['Psychological' by Lemi plays]

Mike (03:02):
Partly, you know, training for the zombie apocalypse, right? You gotta you need at least like 18-20,000 steps a day to outrun, be in good enough shape to outrun zombies.

Athena (03:13):
Is that so?

Mike (03:14):
Yeah. Yeah.

Athena (03:15):
I actually don't know how many steps would allow you to get away from-

Mike (03:18):
Well, 17,000.

Athena (03:18):
Okay.

Mike (03:20):
You know, no heart disease. This according to the bad media portrayal [unintelligible] [laughter].

Athena (03:28):
I see, I see.

Mike (03:30):
But I think zombies are harder to fight than heart disease.

Athena (03:35):
So I guess it's an open question though, right? I mean, have the empirical studies been done actually to see if [Mike suggests, "More research is needed."] zombies are harder to fight than heart disease?

Mike (03:44):
Yeah, there hasn't, they haven't been pitted against [Athena says, "That's right."] each other in a, in a direct um in a direct way.

Athena (03:49):
Yeah, we need like a randomized control trial really to-

Mike (03:52):
Although apparently you can't! Did you see just this paper that just came out? Uh, you know, if you, any type of randomized trial, whether it's for like blood pressure medication or you know, this type of schooling, that type of schooling or anything. People are like, yeah, that Choice A sounds pretty good- seems reasonable. Choice B, that seems pretty good. But the idea of like splitting up population sample and testing A or testing B, people don't like that. Across like thousands of people, lots of conditions. People don't like the idea of being experimented on and forced to be randomized into one condition or the other even though they have no problem with either of those conditions.

Athena (04:40):
That's interesting.

Mike (04:41):
Yeah, it is interesting! Just people don't want to be guinea pigs I guess. Um, so-

Athena (04:47):
Yeah, well every time you pick up your phone, and you're on your social media, like I mean those ads, like a lot of them are A/B designs, right. With like some people getting more than other people getting the other. So we're being experimented on all the time!
Mike (05:00):
Exactly. I know! Uh, but maybe it's just the idea of knowing, right?

Athena (05:05):
Mhm.

Mike (05:06):
If all you knew is that you were put in one condition but didn't know that there's other people out there getting potentially a placebo. We're getting a different trial somehow it seems people think it's a little bit unethical, which is weird. So heart disease zombies, you know? Might have to wait a little bit. [laughter] Uh, IRB approval might take a while.

Athena (05:30):
I mean, in general getting IRB approval for anything involving zombies is apparently hard.

Mike (05:30):
I would think that would be exempt.

Athena (05:33):
It's a question of whether they can give consent or not.

Mike (05:41):
Mm, well certainly doing experiments on zombies is probably okay cause they're undead right?

Athena (05:48):
I don't know, but if they're-

Mike (05:48):
What's the worst that could happen? [Athena laughs] Right? They're already undead.

Athena (05:52):
I mean you have to show that it could potentially benefit them or at least not harm them. I don't know. These are, I think important questions and we should actually get them out of the way now before the zombie apocalypse. Right, because like when the zombie apocalypse comes, we need to be able to do research on the zombies. And if we haven't worked out the IRB, it could be months before we have the approval to actually, you know, do the studies.

Mike (06:17):
Huh. [Athena agrees]. So do you think there really is a way to prepare for the zombie apocalypse?

Athena (06:26):
I think that we at least can start having some conversations about it, and actually, that's why you're here. That's why we're here today.

Mike (06:36):
To help prepare? It's probably going to be like one of those things like the tragedy of the commons, you know, that there's no technical solution. You know, it's, it's our own failings that will, isn't that the thing? Every zombie movie.

Athena (06:45):
Yeah, I think we need like process, we need to have like systems and processes and like, you know, how would we would do a science and the zombie apocalypse, how we would help each other. Like, you know, we don't know what kind of catastrophe might befall us, but there are processes that if we have them in place could help us dynamically deal with, that's at least what I what I think. But maybe before we jump in, could you introduce yourself in your own words cause we're just like off and running! [Athena laughs]

Mike (07:14):
Yeah I noticed this little creature here in front of us.

Athena (07:20):
Yeah it's a field recorder.

Mike (07:21):
So okay good!

Athena (07:22):
So yeah, we're here your office!

Mike (07:24):
Yeah, we're here in my office. Uh, so I, my name is Michael Gurven. I'm a professor of anthropology here at the University of California Santa Barbara.

Athena (07:34):
And you work on small scale societies and health. And can you give like a little one minute kind of your interests and what you, what you study?

Mike (07:46):
I guess on one respect I share a similarity with you, that weird, a weirdo that [Athena agrees], that does lots of things.

Athena (07:54):
Like an interdisciplinary person.

Mike (07:56):
You do, you have a nice way mashing them together. Uh, you know, cooperation pervades all from, from zombies, cancer, [Athena suggests, "Humans even!"] generosity, disaster, everything. Yeah. Right. So, yeah. So I've been working two decades with small scale populations, hunter-gatherers where horticulturalists and you know, on a variety of things. But, but like you, I've been very interested in cooperation and how people deal with kind of collective concerns, especially just how they manage their own risks and how do they, uh, ensure good health when you don't have health insurance, you don't have life insurance, you don't have supermarkets to store food. Um, so how do you deal with the day to day ebbs and flows of, of good fortune and bad fortune. And so yeah, that's been kind of an ongoing theme for a lot of my work. And then I do think it blended nicely then with thinking about health more broadly.

Athena  (08:59):
Mhm.

Mike (09:01):
Uh, and cause certainly part of our cooperation is what on many, many levels, uh, from day to day to like those types of insurance policies we have in other people's bellies and brains. Uh, that, that, you know, helps weather us through lots of bad times.

Athena (09:20):
Yeah. Can you explain that a little bit more? [Mike laughs] Like how do they, like how do the insurance policies that we have in other people's brains, I love already, like we're talking about brains. Um, like how, how do we, you know, insure ourselves against the things that are like uncontrollable, like through those relationships and through, through brains, especially-

Mike (09:39):
Yeah and without me just reminding you of all the debt, you know, all, all the good things I've done for you. Actually, that's why I'm a terrible person! I'm a great person [Athena laughs] actually to like to buy you lunch because I never remember I've done that. Uh, and then, you know, the next time you go out, oh, let me get it this time! And then I'll do it again and again. And it's like, wait, sustain one-way flow. But I don't think it's that way. But you might know that it's that way. So you win. We win!

Athena (10:08):
Yeah. Well, I, I'm all about need-based transfer, so, you know, [Mike laughs, "Thats right."] I also, it's like why, why keep track if ultimately we're fitness interdependent.

Mike (10:16):
Mhm.

Athena (10:17):
Like if we rely on each other, the zombie apocalypse comes and you know, and you're alive. I'm probably a lot more likely to survive. Same if like the zombie apocalypse comes. Yeah. Maybe I could help you out with something. It's much better to have a bigger team in the zombie apocalypse!

Mike (10:32):
That's right! Well, and, and definitely when the apocalypse comes, you want to be able to distinguish your fair-weather friends versus the ones who are gonna who actually reciprocate [Athena agrees, "The ones who actually care about you."] just because they know others are watching or whatever. Yeah, and so-

Athena (10:50):
Yeah. How do you find those people who actually have a true like intrinsic valuation for like your life and wellbeing?

Mike (10:58):
Ooh, that's, well, if you had the answer to that, you know, you, you, you'd be paying people to do this podcast for you! [laughter]

Athena (11:06):
Yeah.

Mike (11:07):
Uh, yeah. No, I think that's the big, that's the big question is not why, uh, who was it? Maimonides wasn't really like the highest form of giving, uh, was to give anonymously. Right? Where you essentially are stripping away any of the potential obvious benefits: reputation, status, reciprocation that you could ever get from helping anybody. Uh, but if you have secret cameras, and those are the kinds of people who would be like, you know, that's who you want to defend your life!

Athena (11:39):
Yeah. But then you have this like weird situation where then the only way you can really signal that you're truly, really, genuinely cooperative is to take all of those things away that could possibly signal it. So then you're like-

Mike (11:51):
What is that? What's left? What's left? [Athena laughs] Well, yeah, I mean, I guess that's the thing, right? Isn't, you know, lots of studies, right, seem to show if you vary conditions a lot, you know, people's behavior changes. But that there's some folks who are sort of stingy and nasty no matter what. Some people who are kind of awesome no matter what. And then everyone else in between that is very flexible. Attune to who's watching and the cost and the benefits. And so I guess the idea that if you try and get some of those people who are going to be out there sort of consistently on your side. Yeah, but yeah, that's uh-, yeah-

Athena  (12:30):
I think there's also another piece of it which is like, you know, just because like, you know, reputation might be part of it. That doesn't mean that there aren't other components. Right? And so I feel like there's sort of this tendency that people have in like the cooperation studies world where it's like, oh, there was some element of reputation or some possibility they might get paid back, and therefore there was no like intrinsic value that the person had for the other person just because there's the possibility of that. But it seems like for any instance of giving or resource transfer, there could be multiple reasons. Like you could be doing it because you see that they're in need, and you think maybe they'll pay you back. But it's okay if they don't. Right. And so I think like the, this idea that any instance of a resource transfer has like one explanation and once you pin it to something that could be counted as like a, you know, payback or reciprocity, then it's almost like nobody's searching for any other explanation.

Mike (13:33):
Well, what do you think about this idea though, that if you, if you peel back the layers by stripping away this incentive and that incentive and that incentive, that center at the, at the heart of the center of that onion, I'm getting your inherent intrinsic, uh, other regarding, you know, kind of preference. Do you think there's anything, there's a there, there once you've stripped away all those incentives or, or are the incentives just really key and these, some of the incentives are always there?

Athena (14:03):
I think it's, I think that it's hard to strip everything cause like we evolved in a world where there, you know, it was just part of an act of like helping that there would be, you know, the possibility that it would become part of your reputation in one way or another. So, um, so I think it's hard to like experimentally, like take all of that away and, and clearly like, you know, experiment, show people respond to like the anonymity. They respond to like whether people can see what they have or not and these things affect their behavior. So I think, you know, we are very attuned to the reputational things. But that I think there is a- there and especially like if you look at, you know how, do people behave in really challenging situations, you know, like after disasters, you know, maybe how they would behave in the, you know, an apocalypse, a zombie apocalypse. Like when your fitness is really just interdependent with someone else, right? And you know, your ability to survive is actually dependent on someone else's welfare also, then you do get the sort of, you know, intrinsic valuation that I think like is, is rooted in this kind of fitness interdependence. So like, I think there is a, there, there of like, you're intrinsically valuing somebody else's welfare, um, at least emotionally. Now, you know, evolutionarily that might be because it's just better to have more people around who can help you if you need it. But I think the way it feels emotionally is just like you really care about someone, and I think that's totally legitimate.

Mike (15:44):
Exactly, right. Yeah and it is a nice shortcut. I mean, I think, uh, you know, now it's, uh, been some years, but you know, way back when, you know, trying to bring some of these economic experiments to, you know, field context and, you know, I think everyone's sort of a priority, you know, hunch about things was, oh, you know, a hunter- gatherers. These small scale societies is, are there, they're sharing food all the time, every, uh, there's not very many possessions and everything's out in the open. And so the general expectation is that, well, you know, if Americans and Europeans, you know, are giving away half the stakes and some of these kind of the pie of these games and you know, and they get all angry and punish if they receive, uh, the short end of the stick, uh, that we would see the same thing if not even more generosity and punishment in, in these kinds of small-scale societies. And, and I think it was very telling that if anything. Well first of all, the results were all over the map. But if anything they tended towards actually less generosity, uh, less willingness to punish. Especially in third-party punishment, it's like as long as none of it. [Athena agrees, "Yeah."] And, and, and I think this is really important because you know, it's all just like, this doesn't matter the context, but this abstract notion of, you know, giving to others and you know, and framed in this particular kind of way, you should, you should expect to get more of it. But this notion of like fitness interdependence is really critical. And I think, uh, first of all, if your, if your fitness is interdependent with lots of other people that you potentially are interacting with in these games situations, then if I effect on one little particular game, which is already a bit weird in the first place, uh, first of all, people were stingy to other people and it wasn't like, oh, because it's, you know, why, you know, they understand it and I know, well, you know, that's what they would do if they were in that first-player role and they wanted to be paid publicly in front of everyone else. So it wasn't, you know, that people knew who they were. Uh, so the reputation, people weren't worried that their reputations were going to be, uh, damaged cause they weren't, they didn't think that their behavior in this game was gonna somehow automatically put them with a scarlet defector you know label.

Athena (18:03):
So it implies that we're like kind of bringing some of our cultural baggage [Mike agrees, "Right, yeah."] To these ideas about what is cooperation and what is a good reputation as a cooperator, or as a punisher.

Mike (18:14):
Exactly. Yeah. Yeah. Yeah. And this one of the big things I kind of took away from some of those things, which is just the whole concept of being anonymously paired with a stranger. [Athena says, "That's crazy right."] Even if you know it's someone in this room, but the way that we have this knee jerk response to potentially be, not hostile, maybe not altruistic, but at least tolerant of some stranger before until you get new information versus the idea that a stranger already like not in my world, fitness interdependence is potentially zero. [Athena agrees, "Right, right."] So uh, and my history of past interactions might be fairly exploitative. So I don't even want to entertain that possibility if there's a chance I might get screwed over. And so yeah, this is how you get cooperative people acting fairly uncooperative in some of these experimental situations but-

Athena (19:05):
Yeah. Um, can I ask you about the apocalypse?

Mike (19:10):
That's why I'm here!

Athena (19:10):
Yeah. So you gave us a talk like, I don't know, it's about six months ago at ASU, something like that. [Mike says, "Mhm, mhm."] Um, where you talked about like what we can tell from looking at kind of the history of small-scale societies in terms of like the like decimation of populations. [Mike agrees, "Mhm, mhm.'] And I was so intrigued by like, what this potentially means. So like, I don't know, maybe you could give like a, just like a brief overview of like what those findings were like, how you sort of figured out that like in human evolutionary history, there've been essentially like these catastrophic things that have happened fairly regularly.

Mike (19:53):
Right, right. Uh, yes. Thank you for coming to that talk. [laughter] I remember, and I remember, I remember your question. Uh, cause I saw that twinkle, I knew you were thinking about zombies when that came up. [Athena laughs] Uh, but yeah, so, um, basically, you know, the, the, the, the research was, is kind of asking, you know, our, our best kind of hint of what life might have been like, right. As, you know, looking in our contemporary, uh, populations that live, you know, more hunting and gathering lifestyles, small-scale subsistence and whatnot. And, and yet when you look at all those populations, they're all doing fairly well in terms of their, the just births and deaths, you know, they're all in positive growth.

Athena (20:41):
Well and just like a little bit of context, like these small-scale societies, they're our best guess for what human history looked like for like a long time.

Mike (20:50):
Right.

Athena (20:50):
For many thousands of years going back. Like, is that a good model for societies?

Mike (20:56):
Yeah, exactly. Yeah. For, you know, depending on the question. But yeah, and again, all the [Athena agrees, "A hundred thousand years or something."] usual caveats, so not living fossils and blah blah blah. But like there, but it's sometimes the best evidence that we have to, to at least, you know, think about some of these questions about life ways and, and-

Athena (21:14):
Like since the emergence of homo sapiens kind of, or like-

Mike (21:17):
Right. Yeah.

Athena (21:19):
Well how many thousand years are we talking about?

Mike (21:20):
Oh, well, I mean it depends on the question, right? But if you want to say modern, you know, humans, you know, 150,000 years ago, if you say, well, it's certain technology and we want evidence of, you know, art and other things and you know, maybe still, you know, fifty to a hundred thousand years ago. But [Athena agrees], plenty of time.

Athena (21:41):
Right so they can be this model, this sort of, you know, at least we can gather from looking. If you look at enough of them and kind of look for patterns, what life probably was like for human ancestors, for a long time, and therefore like, long enough to potentially also have affected our evolution.

Mike (21:59):
Right. And you know, and we recognize of course that, you know, if you're still hunting and gathering in the 20th, 21st century, then you know, maybe you're actually living in the somewhat kind of marginalized area that isn't great for farming. And so if that's the case and yet population growth rates are still really high in those populations and maybe even in the past times could have been even better. So it's a, it's an open question but, but what we do know of course, that if you took the observed population growth rates today-

Athena (22:29):
And can you maybe just break down what a population growth rate is?

Mike (22:33):
Oh yeah sure. So basically, you know, anything that increases the population, so births, migrants, you know, anything coming in is increasing the size of a population and deaths and out-migrants is, you know, decreasing the population. So if we ignore migration for the moment and just say when there's more births than deaths, you know, population is growing and if it's growing-

Athena (22:55):
So you're looking for a particular small-scale society, how many babies are being born? What ages are people dying? And like is the population growing overall or decreasing?

Mike (23:06):
Right? Yeah. And something that like we often, it's hard to think about the meaning of numbers, but like say I say three percent, there's like, yeah, that's a tiny number, right? But if a population was growing at three percent, then it's like, what is it, twenty years? It looked something like twenty years. Every twenty years, that population would double in size [Athena exclaims, "Wow!"] Regardless of its base population.

Athena (23:29):
So, even shorter than a generation, you've got a double.

Mike (23:33):
Right. Exactly. So, so that's why I even have, it's like a homework assignment, in one of my classes that, uh, one of the populations I've been working with for a while, uh, the Tsimané in Bolivia, the average woman has nine births over her lifetime. And the mortality rates, you know, have been, have been declining a little bit. So the growth rate-

Athena (23:53):
What are the mortality rates?

Mike (23:53):
Well, so the life expectancy at birth was probably in the low forties up until like, say the early 1990s and now it's probably in the fifties. Um, but, uh, that's an average life expectancy but when you take all that into account, uh, the population growth rate is 3.8, almost four percent. So like, and it's almost like every time I publish a new paper on the Tsimané, I have to revise the estimate of the population size cause it's just growing and growing. [Athena says, "Right."] And at that rate, you know, the homework problems I, at what rate will we all be Tsimané like in the world? [Athena laughs] And it's actually not that, you know, far along. And that's why I like these small numbers, it seems fairly, you know, insignificant, but-

Athena (24:36):
Yeah a rate that might be small, but you get the compound interest sort of factor. Right.

Mike (24:40):
Exactly. Exactly. So basically the basic question, was like, alright, all these small scale societies and everything we know about humans that, uh, you know, that we, that we pat ourselves on the back, that, you know, we have all this cooperation of multilevel, across, uh, and within generations and that, you know, maybe even, you know, having older generations that are kind of there to, you know, tell stories and, and socialize children, let alone just, you know, babysitting and taking care of, uh, a wide range of needs and, and training, and skills, uh, investment, and all that stuff. Um, all of this is in the context of, you know, living populations today. And so if all those things existed in the past, how is it possible that all these populations are growing really rapidly, but they could not have possibly been growing that rapidly in the past on average, over long stretches of time. Cause you know, there would either, there was a massive, like, you know, zombie apocalypse, you know, generate many, many, many generations ago, uh, or it just doesn't make sense. Uh, and so there must've been zero population growth over most of our species history on average, over long stretches of time. And of course that means yeah, you can get long-term zero population growth if there's just lots of ups, and downs [Athena says, "Yeah."] And booms and busts. And so basically just a cause now I think your listeners are sleeping. [laughter] Uh, they, they, um, uh, that-

Athena (26:15):
So the idea is like, you've got you know a lot of human history. There was a fairly stable population size, [Mike agrees, "Yeah."] We think?

Mike (26:21):
Yeah and so if you say, well, what, what would have to change to make modern populations today have zero population growth? And so, you know, partly it was a modeling exercise like, well, okay, if you take the observed fertility on average hunter-gathers tend to have about six kids. So how few kids would they have to have? How many fewer kids will they have to have to get zero population growth? And it turns out if you just altered fertility, you would have to have so few kids that that's fewer kids than we've ever observed in even in natural fertility populations of hunter-gatherers, except whether we know there's like sexually transmitted, uh, based, like secondary infertility and things like that. And similarly, if you go the other side, well, let's hold fertility constant and you just had to increase mortality, well then you'd have higher mortality than we've ever observed in any contemporary population. Even living under, not just like last twenty years, but living under, you know, fairly, you know, pre-contact conditions.

Athena (27:22):
So if we kind of frame this in terms of like, um, like, uh, you know, super, um, top-down, like, you know, [Mike says, "Yeah, yeah."] regulations of like a population size or two ways you can get that right. And one is with like controlling fertility, right? You can only have two kids and the other is with like a Logan's Run kind of solution, right? [Mike laughs] Where it's like, alright-

Mike (27:49):
Would have said hard target. Uh, how does it feel to be haunted? You remember that JohnWu. Jean-Claude Van Damme. Uh-

Athena (27:59):
Right. Yeah. So you need to either have like a really high rate of death or like, you know, um, you know, early death or you need to have some control, right? Of the population, the growth side. So, so your question is kind of, you know, given that we know that human population size was stable for a long time, [Mike "mhm"] like, you know, is it a like top-down China, one World Cup or one baby kind of situation or like a Logan's Run, you're thirty and you're dead kind of situation.

Mike (28:28):
Right? And, and the now to cut right to the chase, you know, what, what seemed most plausible cause you, cause then an alternative is like, well that's just on average you're just changing mean fertility or mean mortality. [Athena follows] But what if you just all of a sudden, what have you just kind of, you know, threw an asteroid, you know, at people and just like massive catastrophe. Uh, and basically if you already did-

Athena (28:55):
There's another possibility!

Mike (28:56):
Yeah. [Athena laughs]: Right, right! And I'm being biased too like, cause you'd think there shouldn't just be annihilation occasionally. There should be like big bonanzas too, right? But I was being like, no bonanzas. Is the zombie apocalypse ever good? Like what, what's the positive version of a zombie apocalypse? Like, like something heavenly like angels come and put chocolate cookies, like just chocolate cookies show up at your doorstep all over the world.

Athena (29:40):
Well it's like Christmas, or any holiday, where, you know, there's like a, some sort of special entity comes down and showers you with gifts, right. Winter holidays-

Mike (29:48):
Right winter holidays.

Athena (29:48):
Are the opposite of the zombie apocalypse.

Mike (29:50):
Right. So, well it turns out, yeah, sorry. Yeah. Yeah. So it turns out if you just have the bad apocalypse, not the good one, uh, it would have, you'd have to have an apocalypse like almost every like ten years, five years. Uh, and they'd have to be pretty severe. [Athena asks "How severe?"] In order to bring, well, like wiping out maybe like a third of the population [Athena ask, "Seriously? Every 10 years?"] Yeah. In order. Yeah. In order to, and so yeah, in order to get zero population growth. And what- the thing that's nice about that is like-

Athena (30:19):
Wait! This is so dark, you just said 'the thing that's nice about that'! [Athena laughs]

Mike (30:26):
Well look, I just watched you give a three hour talk on cancer, yesterday, while smiling the entire time, which is an amazing ability by the way! I can't like walk and chew gum at the same time. Yet you can walk, talk, and smile at the same time. I've never seen it before. Um...

Athena (30:45):
Okay. So you we're going to see good thing about-

Mike (30:47):
Yeah! It would have to happen all the time. And so basically the most feasible thing cause net, cause we in all these populations in living memory, people can tell you, you know, was there an apocalypse in the last ten years, fifteen years, twenty years, a hundred years, you know, in living memory. You know, the oldest people, uh, and that doesn't seem to be the case. There was no asteroid, there was no zombie apocalypse. I mean there were little epidemics here and there and things, but nothing that looks at it all like that. And so basically the only way to really get zero population growth that seems the most reasonable is basically a combination. If fertility were a little bit lower, if mortality were a little bit higher and then you could have a more feasible kind of apocalypse kind of schedule that was hitting people. Uh, but basically, but the, the, the take home that you were think- maybe might like, because your morbid [Athena laughs] is you can't get it without some apocalypses so that, you know, some degree of fairly intense apocalypses would have been a routine.

Athena (31:52):
So what's your aspect like, like how like-

Mike (31:59):
For my time machine?

Athena (31:59):
And here I'm just asking you to like speculate what you think is the most likely scenario of like how often, how severe, like one potential combination of like severity and timeframe.

Mike (32:10):
Right! Yeah. So now you're asking me to actually remember my own findings? Um... [Athena laughs]

Athena (32:17):
You can just give an estimate!

Mike (32:19):
Right! Yeah. Well you're, you're, you're, you're seven archeologists in the audience, uh, will probably be like, well, duh, of course catastrophes are a part of human history, but, you know, I thought we could go a little bit further than that by actually maybe trying to answer your question. And I think with a, with a reasonable, with some, you know, moderate like adjustment of fertility and mortality, then I think even like every fifty years, if there was like a, you know, 30%, 40% increase in mortality rates, you know, that, you know, with a bunch of assumptions, blah, blah, blah, say it wipes out like 20% of the population, 30%, uh, that could, that could lead to, you know, stable population, uh...

Athena (33:06):
So we're talking about in the lifetime of any average individual, [Mike suggests, "There could have been something."] some event where 25% of the people in your group die.

Mike (33:13):
Right. And now if it's a little bit more severe than maybe say, you know, every 100 years or something like that, or 150 years. Uh, basically the closer to a living population is to zero population growth, the longer they can go without having experienced a catastrophe. [Athena suggests, "For the model?"] Um, yeah. For the, for, for the model. And, and um, so if you wanted to put a big kind of open window on that, yeah. Let's say, you know, 50 to like 200 years. Uh, so if not, you're living memory, but maybe within your grandparents living memory. And the stories that, that, that the, the, the possibility of catastrophe, and we modeled this also, they're sort of unpredictable, right? So it's one thing if you know exactly when the meteor is coming to hit versus even if something only happens every one hundred years, but you never really know-

Athena (34:10):
Where it's like a flood, [Mike adds 'if its coming'] or infectious disease or-

Mike (34:13):
Right, and because that's on average you could actually, you could have them like one right after the other, and then none for a long time. And, and, uh, and things like that. So, so, yeah. So, you know, I think that these kinds of catastrophes have, have been a part of us for a long time now, but, you know, we're not terribly unique in, in many ways. Uh, and so certainly these types of things must hit lots of species, right? Uh, I think you know, Malthus would probably agree with that. Uh, and so one thing that maybe is kind of interesting about humans is that they might have a, just a really good ability to bounce back, right? [Athena says, "Yeah."] So, so even, uh, you know, Rob Walker and Marcus Hamilton, you know, have this kind of compiled everything we know about, uh, indigenous populations, and in the Americas, particularly in Brazil, like around the time of contact and after contact and basically what they, what they found just like over 200 different populations over a century and a half or so. Um, I could be making that up. I think it's true. Uh, basically, yeah, contact sucks. Uh, and over up to, on average like 30 to 40% of the population was wiped out, but within ten years after contact, you basically were seeing positive population growth. And within twenty years it was like really fast population growth and that was, you know, over a broad range of time. So this ability to bounce back uh-

Athena (35:46):
And by bounce back, you mean have babies quickly? [laughter]

Mike (35:47):
Yes. So have babies quickly, and right, even if mortality is still kind of on high on average, but yeah to bounce back with, with, with babies. And so that what looks like, yeah, something just coasting along on average when you zoom in, you know, there's, you know, population growth might look a little bit like, you know, the, the edge of a saw, you know, increases, crash, increases, crash.

Athena (36:12):
So this, I mean, maybe this is because the way my brain works, but I'm thinking like, okay, there's some sort of apocalypse, some sort of catastrophe, and then afterwards, once things get a little better, then everyone's just like going crazy having sex and having babies.

Mike (36:26):
Yeah. Or territories open up, right? It's like, even like if some of the hunter-gatherers today, like the Aché, right? They, we're living in sort of pioneer conditions, like a third of men, Paraguay died during the Chaco War. Uh, and so here's like all this territory and you've got the average Aché woman was having eight kids, so fairly high fertility for a hunter-gather, uh, as a result. So, you know, the Jesuits had planted all the citrus fruits, too, and so the ecology, you know, was definitely favoring, favorable for these pioneering conditions and the ability to thrive under those conditions. So the one thing that kind of, that actually came out when, when, when Kevin Langer-Grabber, uh, one of your colleagues, you know at my talk was like, I don't think you've got the chimpanzee fertility right. And I was like, 'Hmm, you might be right, but I think I am right, and it's your colleagues and your field site actually that is part of the answer,' and the thing that he was pointing at is that it was showing that fertility rates on average in chimpanzees, were fairly similar to humans. But, which is like weird because we think of, you know, humans have higher fertility, but it was like it's the potential fertility if chimpanzees were to live throughout all of adulthood, they could potentially have lots of babies. So the average number of babies over a female's life cycle, if she lived throughout all of that could be, you know, six to seven babies, but what's really kind of interesting about, uh, and then his, his knee-jerk response, which any chimpanzee expert would say, 'Hey, but everyone knows that your average timing between births for chimpanzees is like five to six years!' Whereas for humans under natural fertility populations, that's fairly long cause [Athena suggests, "More like four or five."]. Yeah. And that's even kind of long, right? The, the, the, the !Kung everyone's favorite hunter-gatherer, uh, gods must be crazy, uh, four years, but like, you know, the Tsimané it's like two years, other places, three years. Uh, and what was interesting is that in chimpanzees you get, you can get an inner birth interval that's like two to three years, but that's when the babies die, when they don't survive throughout infancy. So when conditions are kind of good and infant survival is actually high, the timing between births is like five to six years. So that's very different situation in chimpanzees and humans.

Athena (38:53):
Yeah, so I have to ask like, so given all of this like the, it's fairly likely that during our evolutionary history, you know, in the lifetime, you know, in a person's lifetime or at least in like the intergenerational memory window, like there were, you know, apocalypses happening, we'll just call them apocalypses like 20 to 30% of people dying. That's kind of like, that would be an apocalypse today, right?

Mike (39:17):
That would be.

Athena (39:17):
So do you think that as humans, we actually have adaptations that we have evolved systems for dealing with apocalypses? Like either, you know, proactively like managing the risk and preparing, or like when the apocalypse hits, like responding, do you think there is like a, you know, a whole field of evolutionary psychology and evolutionary anthropology that should be like a whole field of study about apocalypse adaptations?

Mike (39:51):
Uh, yes, and yes! I do! [Athena laughs] And I think, you know, cause one interpretation of like, 'Oh, there hasn't been the apocalypse, uh, in the last one hundred years in a lot of these small-scale societies.' It's not just that, 'Oh, well there's contact and things are always all better now.' Uh, it's that all people might take things into account so that there's storage. So if there is a bad famine in a particular year, you might not be able to completely control the weather, but you can control how you respond to, you know, crop shortage, and so of course, all the, you know, the many ways that sociality, uh, you know, helps deal with risk and different types of risks, especially if you're sorting with folks who, you know, the disasters hit them at a different time-

Athena (40:41):
Right and you can transfer a risk a little bit, right? Yeah.
Mike (40:43):
Exactly! Exactly! As long as, you know, they're there for you and when you need it [Athena adds, "And you need to know that, and you need to know that they're going to be there for you!"] And you can rely on them. Yeah, yeah, yeah. Exactly. The big problem with these days is if there is an apocalypse, and our cell phones don't work and you have no way of communicating with your, your people in your, in your, [Athena shouts out "Z-Team!"] A-Team! On your Z-Team! [Athena & Mike laugh nervously, and glance quickly over their shoulders] Uh, I'm not sure what, what would go on there, but, um, yes. So... I do think-

Athena (41:13):
There's multiple ways of managing risks.

Mike (41:14):
Yeah. I do think there's lots of things that, uh, yeah. Uh, and there's ways, that you know, but I think it takes, there's lots - as soon as there's lots of people who are managing risks, you know, there's people who then can discount and, and-

Athena (41:28):
Ah, so there's like a free-rider problem!

Mike (41:30):
Yeah free-rider problems, all those moral hazards and stuff-

Athena (41:33):
Ah, so it's like other people are worrying about it. So I don't have to kind of?

Mike (41:38):
Exactly! Exactly! Um, yeah. But, uh, certainly, well, certainly I think, you know, many disasters, this is where I think, right, in a world with climate change, uh, and more and more disasters, water scarcity, uh, there's like, you know, many zombie apocalypses every day, right?

Athena (42:02):
Yeah.

Mike (42:02):
And so, you know, people should be giving you more money to have more zombie apocalypse meetings! [Athena laughs] Ah hell, if thinking about zombies gets people to really think about, you know, these kinds of issues, uh, and yeah, I think that that's good! [Another brain taken] Um, although going back to the, I guess the certain recovery and population growth isn't exactly the kinds of solutions that we're thinking about today. Right?

Athena (42:31):
Right! Cause we want to, you know, make it so that 25 or 30% of people don't, right? Like we value the humans that are alive right now.

Mike (42:39):
Well, this is why I didn't understand! Alright, so I have not seen Avengers: Endgame, but-

Athena (42:46):
I haven't either!

Mike (42:46):
Okay, Well, but, [Athena adds, "But my kids are obsessed with it!"] okay, but in studying for that film, uh, I finally saw Infinity War.

Athena (42:55):
I have seen Infinity War!

Mike (42:55):
Okay! Well then I did not understand Thanos, the logic of Thanos' plan, right?

Athena (43:01):
'Yes! Like actually, this is totally relevant to our conversation, yeah!

Mike (43:01):
Like wipe out good. You know, wipe was it, was it a half? Half, so wipe out half, but first of all, let alone the logic that you're wiping out half to save people, but you just killed half the world's population. Uh, but also ignored the whole love, the whole notion of, uh, you know, trophic levels, right? You wouldn't want to kill, oh, sorry. Like, you know, like you got your grasses and what eats the grasses, you know, then your herbivores and what eats the herbivores? You think, like-

Athena (43:35):
Things that are dependent on other things that's important, right?

Mike (43:38):
Right, so, you know, you, you'd want to, you know, pick for every carnivore you're picking off. You probably don't need to pick off as much, you know, plant species and whatnot. So the logic of like, just completely eliminating, uh, half, uh, but let alone, you know, this whole other, it also gets at these old themes about, um, what was it, Mao? Mao Zedong. I'm just quoting all the winners today! Uh, uh, you know, an extra pair of hands, right? Versus an extra belly to feed. So, you know, with each additional person, is it kind of a net benefit or net cost and, and you know, does population pressures spawn innovation and get you out of that, uh, the being on the margins where it's a dog-eat-dog world? Uh, or you know, is there some ability to kind of spark and, and Thanos, apparently [Athena say, "He doesn't believe it"], he doesn't believe it. He thinks, you know, every being takes in, you know, materials and takes more. But that's, you know, that's a big assumption.

Athena (44:50):
It is a big assumption, yeah!

Mike (44:50):
But based on that assumption, which he didn't really test thoroughly with randomized experiments, [Athena says, "Well you know-] he said 50% of the world's, universe's-

Athena (44:59):
Yeah, well, that's the problem with all models, is the assumptions that go in that aren't tested, and Thanos is a great example of that!

Mike (45:07):
Exactly! So maybe it's just all about his, his hubris. So to think that he knew the answers enough to risk just sacrificing half of the universe's life and what, and the other thing too is at least take that life and, and feed it, or like, notice they just disappeared into dust. No one eats dust. So all of that wasted food, that alone would have gone to sustain the universe for like at least another millennia!

Athena (45:39):
Yeah, 'So this is how I behaviorally collared this!' Like interprets Infinity Wars! It's like the energy! What happened to the energy!

Mike (45:42):
Yeah what, exactly, yeah! Did it go to create a new universe? Oh, maybe that's the next, maybe this is what happens in Endgame! We'll never know, because I only have two friends and they both have seen, you know, Endgame, so now, either I need new friends, or I just have to see it by myself, alone... crying.

Athena (46:03):
Yeah. Yeah. Well I, I, it's kind of interesting actually that these sorts of issues do like come up in, you know, fiction and in philosophy, right about like how do you manage, you know, human populations is it something that has to happen actively. Is it something that can happen passively and-

Mike (46:24):
Right, but don't you think that this, you know, going back a little bit to the unpredictable catastrophes, just the very fact that, you know, zombies are so fascinating, you know, representing that potential threat that can annihilate us at any, at any moment. So why else is that thought there if that potentially wasn't part of the potential to, to happen even under like modern conditions where presumably things are supposed to be better now than ever before.

Athena (46:53):
Yeah, so why do we have this sort of latent fear that maybe comes up in things like zombie apocalypse movies, or you know, the Endgame or like, you know, like these, these things are like part of our imagination. Like they come up in our imagination. Maybe that's not just like, oh, humans are being cute by inventing fictional things. Like maybe there's actually some sort of, you know, adaptation that is there where it's like, 'Oh, let's imagine a catastrophe! What would happen?'

Mike (47:23):
Exactly!

Athena (47:25):
'And how would we deal with it?'

Mike (47:25):
But we'll never know until we see Endgame. Maybe Endgame also explains how Chris Evans played both Captain America and the Human Torch. Did you notice that?

Athena (47:35):
No, I didn't pay enough attention. Yeah. Yeah. Um, okay, so, so what do you think is the most likely zombie apocalypse scenario, like in general or apocalypse scenario for, um, you know, given all of what you know about, like human populations and human history and, and you can choose to take this in whatever direction you want, either serious or not. It's completely up to you.

Mike (48:00):
Well, my, my, my wife would probably... This right here! [Mike laughs] I'm pointing at my cell phone!

Athena (48:12):
You're like did anybody message me?

Mike (48:12):
Anyone more important want to podcast with me right now? [Athena laughs] Agh, oh, dammit! Brian's already drinking beer in my lab!

Athena (48:18):
Okay, well we can finish this up!

Mike (48:19):
No, no.

Athena (48:21):
A-Apocalypse.

Mike (48:22):
As long as they're not getting extra steps [Athena laughs]. So yeah! Well, I mean, I do have a joke, but uh, uh, but about technology, well, particular cell phones and you know, especially as a, you know, there's -- like we had this conversation like two years ago. I was like, well, the, your, your kids are older than mine! And I was like, all right, so what, what, what's the latest, what age do you give them the cell phone and what age are they allowed to, you know, how many hours of screen time on what type of screen? And it's this whole idea of trying to prevent, you know, [Athena suggests, "Them from becoming zombified!"] Their b-brain rotting. Uh, and at the same time, it, it's sometimes you'd want your kids to be zombies cause then they're at least not, you know, screaming in your face, or, you know, jumping up and down on, on, on, you know. Yeah, so.

Athena (49:18):
And your like, 'I'm trying to finish this paper about the apocalypse, like come on!'.

Mike (49:23):
'Stop distracting me while I try to distract myself!' [Athena laughs] Yes, um, right, but so I do think how we kind of are going to use, you know, the fact that there are sad studies that say, just the fact that my cell phone is just sitting there. [Athena agrees] Right, and that it's well and that it's on is worse, but you know, I'm probably not giving you my, my full attention and your listeners my full attention!

Athena (49:49):
You're a little bit zombified by that device over there pulling on your brain!

Mike (49:52):
I know! Well, and I do wonder now, especially because, uh, so even, you know, in Bolivia, you know where I've worked for a while, it's not, it's not like cell phones now exist after there was, you know, old fashioned dial up phones and landlines. [Athena inserts "Yeah! It's like they went straight to that!"] Yeah it's like going straight to cell phones and now, you know, it has the potential for, for internet and, and uh, it's just completely wild and new. And the fact, I mean, every day I have another Tsimané Facebook friend. [Athena is surprised] Yeah! Yeah! And so, I mean, I'm getting up to date on things in Tsimané land. I don't, I just, you know, do a Facebook call. I just, uh, yeah, or let me see your phone, let me look at your call log. And I know everyone you've interacted with, you know, through cell phones, you know, that that would be, you know, that's really interesting and fascinating. Uh, and...

Athena (50:52):
Well, Facebook can just do all of anthropology now, right? We don't even [Mike agrees, "Pretty much."] Need anthropology departments in universities!

Mike (50:57):
Well, Facebook has all of it. They're watching us right now recording this conversation live, feeding it in Romania somewhere. Uh, so yeah, I don't know. I don't know. So that's one form of, I guess of a zombie apocalypse that, uh, maybe is a bit, is a bit worrying. Uh, it is kind of nice to, on occasion when you're in circumstances where there's no phone service, or you don't have your phone and the battery's dead, you didn't bring it, uh, you know, and it's like [inaudible] at first, but then it's kinda nice to well... Not thinking about the hundreds of emails or whatever that they're waiting for you, but, uh, that's actually these days, one of the nicest things still about going back to the field, is not having that connection with technology [Athena adds "Well not for long now!'" Well, I know, and that's the thing, uh, oh, I still tell my family that! [Athena laughs] 'No, I can't be reached. There's no, there's no cell phone towers anywhere!' Actually, it is still true in a lot of places. [Athena laughs] Yeah. But, but, uh, yes, becoming less true, uh, every, every day, every year. Uh, and now even like, uh, you know, the field team, you know, it's like, Oh yeah, you don't have cell phone reception, except if you bring an antenna and you climb a climb up a big tree, and it's like, now you'll get some reception. And so yeah, the world's becoming more and more connected of course. And so...

Athena (52:28):
So that kind of means you need to be like giving up some of your brain's bandwidth all the time to like being tapped into the network. Right?

Mike (52:37):
Well one, you know, I remember a student, again, all seriousness asked, you know, can they use their cell phones for their exam? Like, but like essentially making the argument, he didn't use the word like 'exo-brain', but like the idea that like why do I need to know anything? If I can just store knowledge on my phone, I can Google something, and so since I know that's there, I purposely don't learn it, so you should let me-

Athena (53:02):
You know [Mike finishes his thought and says, "Bring my phone."] You should just tell them like, this, you need to know this for the case of the zombie apocalypse, and in the zombie apocalypse, you're not going to be able to charge your phone [Mike agrees] so...

Mike (53:15):
Or you try to create a test where like, "You know what, go ahead! Use your phone. You're still probably going to fail, so..." [Athena laughs] Or you know, you actually have to know the material and think critically and you in order to, to do well! Uh, so [Athena says, 'Yeah.'] yeah!

Athena (53:29):
Well, Mike, thank you so much for sharing your brains with us for this episode of Zombified. It was really awesome.

Mike (53:38):
Thank you!

Athena (53:39):
Having you as a guest, I feel like I understand the apocalypse so much better now!

Mike (53:43):
Oh, thank you! Thank you for coming to our neck of the woods, having to suffer through weather that's not triple digit. Well it was bizarre though. It was like sunny, and then raining, and then sunny, and then like, so windy that like, I got hit in the face with a wood-chip and I'm like, 'What's going on here? I thought that I'm on the beach, but-"

Mike (54:02):
[Mike shushes Athena] Don't tell anyone. California is supposed to be pleasant all the time, all day, all night!

Athena (54:07):
Well, except for the apocalyptic fires that you guys have!

Mike (54:10):
Right, so again, you're right. The apocalypse is everywhere. Every, you know- and it's funny cause now, well not funny, but you know, my, my, my daughter being young enough to have seen fires pretty much every year. That's actually part of her normal. That's normal! So now the apocalypse would be the absence of fire. [Athena laughs] Like, like that's the anomaly and it's like, yeah. How, how weird is that? [Athena agrees] Uh, so hopefully that won't speed up her life history though. [Athena laughs] I don't-I don't want menarche at age six or seven, no.

Athena (54:45):
Now you're just making like super nerdy jokes! [Athena laughs]

Mike (54:46):
Yeah, those are definitely, sorry, but that's why you have editing. You've already cut me off like 20 minutes ago [Athena laughs] Like, yeah-

Athena (54:55):
I actually, like do very minimal editing or my sound person does very minimal editing, so, yeah! So all of all of this right now still might be on the end of the episode! [Mike apprehensively says, 'Wow, alright!'] Yeah.

Mike (55:05):
Okay. Alright, well thank you!

Athena (55:09):
Maybe we should go get some beer! On the beach!

Mike (55:10):
Yeah, let's do that! Alright, thanks!

Athena (55:13):
Bye!

Mike (55:13):
Buh-bye!

Song (55:13):
['Psychological' by Lemi plays]

Athena (56:31):
Zombified is a production of ASU and the Zombie Apocalypse Medicine Alliance. Thank you to the Department of Psychology, the Interdisciplinary Cooperation Initiative, and the President's Office at ASU. Also big thanks to the Lincoln Center for Applied Ethics. Thanks especially to the brains that help make this podcast, Tal Rom who does our sound, Neil Smith, our illustrator, and Lemi, the creator of our song 'Psychological.' Thanks also to the Z-Team at ASU. You can follow us on Twitter and Instagram. We are @Zombifiedpod and we are 'Zombified Podcast' on Facebook. Our website is 'zombified.org' and if you go to our website you can find some awesome merch. We have t-shirts, and stickers, and if you purchase those all the proceeds will go to support us making more episodes. You can also support us by becoming a patron on Patreon. Um, we are just 'Zombified' on Patreon, you can find us there!

Athena (57:34):
At the end of every episode, I share my brains, and today, what I want to share is some thoughts about how the current situation that we're in with the COVID-19 pandemic, um, relates a little bit to some of the content that Mike was talking about. So we recorded this episode before the pandemic hit, and so that's why we didn't talk about it at all, but I think that there are some really interesting issues that come up in this episode, especially about whether we have adaptations for dealing with apocalypses, dealing with situations where, um, our world is severely impacted. Where there can be high mortality, and in the context of sort of the broader apocalypses that Mike talks about, the current situation with Coronavirus is actually a relatively mild apocalypse, because remember he was talking about, you know, death rates of, you know, 20 to 30%. Um, and what we're looking at with Coronavirus is definitely below that, but at the same time, I think some of these ideas about, you know, how, how are we adapted to actually deal with disasters can apply! So, you know, how do we help to, um, share risk? How do we help each other in times of need? Uh, and also, you know, what role does our imagination play in helping us prepare for risks, and, you know, also when things like the current pandemic happen, how might our imagination, and our ability to envision, you know, potential futures help us to recover? So to me, there is some optimism in this very dark episode, which is that we might very well be adapted for the apocalypse. Thank you for listening to Zombified, your source for fresh brains.

Song (59:48):
['Psychological' by Lemi plays]