Why are we nice? Altruism’s origins are put to the test

Benjamin Thompson

Welcome back to the Nature Podcast, this week: putting theories for why humans are so helpful to the test…

Nick Petrić Howe

…and how to make DVDs with huge storage capacity. I'm Nick Petrić Howe.

Benjamin Thompson

And I'm Benjamin Thompson.

Nick Petrić Howe

First up on the show reporter, Adam Levy is helping us to understand the evolutionary origins of altruism.

Adam Levy

Well, before I do that, Nick, can you do me a quick favour and remind me what's coming up later in the show?

Nick Petrić Howe

Oh, um, sure yes. Later on, I've been looking into ways to make discs with huge data storage capacity.

Adam Levy

Now, Nick, why did you help me out there?

Nick Petrić Howe

Well, it's, you know, it's in the script.

Adam Levy

Well, yeah. But I mean, even if it wasn't in the script, you would have helped out, right?

Nick Petrić Howe

Sure. I guess?

Adam Levy

Well, why?

Nick Petrić Howe

I don't know. It's just what people do. Right?

Adam Levy

Exactly. It's just what people do. But why?

Nick Petrić Howe

You mean why do people help each other out?

Adam Levy

Yeah. How did this behaviour evolve? which is the topic of a study out in this week's Nature. So, thank you, Nick, for your help with that intro.

Nick Petrić Howe

No worries, you're welcome.

Adam Levy

You see, helping each other out is a part of our human nature. Whether that's helping with childcare, sharing information, exchanging goods and food, and…

Sarah Mathew

We help individuals that we know, we help also individuals who we don't know.

Adam Levy

That’s evolutionary anthropologist, Sarah Mathew of Arizona State University. So why did we evolve to help each other out? After all, in many situations, it would seem to be in our interests to not cooperate: to accept someone's help, but then not help them out in return.

Sarah Mathew

Cooperators somehow had to avoid getting exploited by individuals who just take their help but are not going to do their share. And that problem is so powerful that we get very, very little cooperation evolving in nature.

Adam Levy

So how did humans evolve cooperation? When compared to other animals were remarkably cooperative with each other. So much so that we often help someone out even when we're unlikely to ever interact with them again, and so won't get to reap any benefits.

Sarah Mathew

People donate blood, we will get up from our seat when somebody enters a bus who looks like they need the seat.

Adam Levy

So how did our weird way of helping each other out come about? Well, there are two main explanations. Here’s economist Ernst Fehr of the University of Zurich, explaining the first of these theories: the theory of repeated interactions, which argues…

Ernst Fehr

Because we evolved always under the shadow of the future where there is another future interactions, we have an incentive to cooperate.

Adam Levy

So, help someone now so they might help you later. And this theory explains our tendency to help people we won't see again, by suggesting that our altruism evolved when our ancestors lived in small groups and knew everyone and so helped everyone. The other theory called group competition, imagines that it was the groups of people themselves that could have led to cooperation arising as a human norm.

Ernst Fehr

And the key idea in the theory of group competition is that the groups who are more likely to succeed in group competition are more cooperative groups.

Adam Levy

So groups in which everyone is nice to each other would be able to out compete groups where people acted more meanly. Okay, so two theories to explain human helpfulness and Ernst and his collaborators set out to see which of these holds up.

Ernst Fehr

Well, we set up a very large simulation project, and that cooperation game has a very simple structure.

Adam Levy

The cooperation game that the team modelled imagines two players, say they're you and Ernst. To start off with Ernst is given $10.

Ernst Fehr

And I can keep my $10 or I can send any of my $10 to you.

Adam Levy

And a bonus, the money Ernst sends to you gets doubled on its way to you. Now you can return the favour sending all, none or some of your money to Ernst.

Ernst Fehr

So we have this sequential game if you like. You observe what I sent and then you can respond by also sending your amount.

Adam Levy

And again, any of the money you give to Ernst would be doubled. This game sounds very simple, but the model allows for surprisingly complex behaviour and tactics to arise. Here’s Sarah again who didn't work on the study.

Sarah Mathew

Now, there have been hundreds and 1000s of models done before, they usually conceive of strategies based on binary kinds of behaviours. So either you give or you don't give. Here in this study, they modelled cooperation and non-cooperation as a continuous trait, which is more realistic, because you could potentially give back a little less than you were given, you could give back a little more than you were given. So that is, in some ways, the really special thing that this model accomplished.

Adam Levy

So what does this model find? Well, for repeated interactions, this idea that we help someone so they'll help us.

Ernst Fehr

The person who responds to the partners previous cooperation level, always has an incentive to cooperate a little bit less than what the partner did, and over time, the little bit less accumulates and leads to the breakdown of cooperation. So in contrast to what most people in the evolutionary community believe, repeated interactions cannot explain the evolution of cooperation. So that's the first important finding.

Adam Levy

Okay, so according to the team's model, the repeated interactions theory is out. And when simulating the dynamics of group competition, the model finds that this also fails to lead to cooperation.

Sarah Mathew

It flies in the face of two very prominent theories for how cooperation can evolve.

Ernst Fehr

And so we are stuck, so to speak. And then we had the idea that maybe if the two mechanisms, repeated interactions and group competitions, can work together, maybe that leads to a different result. And to our surprise, we found out these two mechanisms of cooperation, when simultaneously active, can explain human cooperation over a wide range of conditions. What the group competitions do is they counteract the individuals’ incentives to cheat a little bit.

Adam Levy

So the model suggests that cooperation didn't evolve because of repeated interactions or group competition. It evolved because of repeated interactions and group competition. And to test this theory, the team investigated what the model predicts should happen when real people play this game. Do they play the game in the way you'd expect if cooperation did indeed arise, thanks to both group competition and repeated interactions? The question can't be answered so easily by getting people in say Zurich to play the game, since there's so many rules and regulations enforcing cooperation in Switzerland. Instead, the study asked people in the western highlands of Papua New Guinea.

Ernst Fehr

And therefore we get much more at evolved behavioural tendencies when you do experiments in Papua New Guinea compared to Switzerland or the US.

Adam Levy

But asking people who aren't so well connected to state or scientific institutions to take part in a study can be somewhat fraught. And to avoid exploitation, it's vital that everyone understands what they're agreeing to, and why. But the team had someone on hand who was well positioned to set up the collaboration.

Ernst Fehr

Helen Bernhardt, who is one of our co-authors grew up in Papua New Guinea, she had intimate knowledge of the local customs and norms in these societies. And that helped us greatly to conduct these experiments, because you have to be sensitive to the local customs and local norms, you have to acquire the trust of the people. And Helen was the ideal person to do that.

Adam Levy

The team wanted to see if these participants would back up the predictions their model had made of human cooperation, namely that if two players see themselves as being in the same group, they'll help each other more and more over time. And if players see themselves as being in different groups, they'll gradually help each other less. So they played out the same game again with a real participants to see if the models predictions held up.

Ernst Fehr

These two predictions could be tested in our experiment in Papua New Guinea, and they both turned out to be true.

Adam Levy

And so the study through its model and its work with participants in Papua New Guinea suggests that cooperation may have evolved not just because humans interact repeatedly with each other, and not just because humans evolved in compete between groups, but thanks to both of these forces. For Sarah, this result is profound not just because it takes us closer to understanding the evolution of cooperation, but because it helps highlight just how many questions there still are to answer to explain why we humans help each other out.

Sarah Mathew

I think one of the most important results in this paper is to really shake people out of this status quo. So I don't think this is case closed, it's more that this is case opened.

Benjamin Thompson

That was Sarah Mathew from Arizona State University, in the US. You also heard from Ernst Fehr, from the University of Zurich, in Switzerland. For more on that story, check out the show notes for some links.

Nick Petrić Howe

Coming up, a method to make discs the go-to data storage system of tomorrow. Right now though, it’s time for the Research Highlights, with Dan Fox.

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Dan Fox

Divers have helped to uncover the remnants of a one-kilometre-long Stone Age wall submerged in the Baltic Sea off the coast of Germany. Researchers used camera images, sediment cores and sonar data to characterise a string of boulders located 21 metres down and around 10 kilometres from the shore. The team counted over 1500 rocks in a formation that stretches 971 metres. Most of the rocks weigh less than 100 kilograms and so can be moved into position by small groups of people. Analysis suggests that the structure ran along the shoreline of a former lake or bog. It was most likely built by hunter-gatherers over 10,000 years ago, possibly as a tool to guide reindeer and other large animals during hunts before becoming submerged around 8500 years ago as the sea level rose. Take a deeper dive into that research in Proceedings of the National Academy of Sciences of the United States of America.

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Young apes get a kick out of teasing each other and joking around when they're relaxed, just like humans do. Researchers recorded videos of five great ape-species – orangutans, chimpanzees, bonobos, and western and eastern gorillas – as they played in zoos in the US and Germany. They noted the primates’ interactions, including how often they try to provoke a response from one another rather than simply playing together. Like cheeky siblings, the apes would poke their targets repeatedly, dangle objects in their faces, pull their hair or stare at them until they responded. All five species seemed to tease each other in similar ways, and were most likely to play in this way, when relaxed. The researchers say that this kind of play probably evolved at least 13 million years ago, before humans’ ancestors separated from those of these ape species. If you've gone ape for this research, read it in full in Proceedings of the Royal Society B Biological Sciences.

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Nick Petrić Howe

Could the humble disc be the future of data storage?

<disk insert sound>

Well, a new Nature paper might make that a step closer to reality, as the team behind it have made the storage capacity of such discs millions of times greater than those currently available.

Min Gu

Oh, I feel so excited. And over the ten years we have done lots and lots of work for that particular goal.

Nick Petrić Howe

This is Min Gu, one of the authors of the new paper. Now the reason that this has been a particular goal is that we, as a society, are producing more data than ever… and we need places to store it.

Typically, that’s currently achieved by hard disks, like you have in your computer, but they may not be up to the task forever.

Min Gu

There are some limitations. The hard disk drives, they are limited capacity. The second issue is regarding the hard disk drive is the lifetime. So, typically the hard disk drive, the lifetime is 3-5 years or 5-10 years.

Nick Petrić Howe

Now optical discs — your DVDs, blu-rays, CDs and the like — can last up to 50 years, under the right conditions. And they also use less energy than hard disks, potentially making them a greener alternative for long-term, large-scale data storage and retrieval. But for capacity… well they are also limited there.

The biggest kind of disc you can typically buy tops out at around 100 GB of storage. To put that in some nerdy context for you, that’s not quite enough for one of the extended editions of the Lord of the Rings in 4K ultra-HD quality. Whereas hard drives can be up to 100 Terabytes — a thousand times more, and a lot more room to store the adventures of Frodo and the gang.

Optical Discs have been limited by how much information you can write on them, which is in turn limited by the resolution of the lasers that do the writing.

Min Gu

There is a physics law, it's called the diffraction limit. So the size of the laser spot on the disk is limited to half of the wavelength, the wavelength of the laser beam we used. So in other words, the smallest bit size on the blu-ray is about 200 nanometres. That is the limitation.

Nick Petrić Howe

When you write data or bits onto a disc you write it in dots, so the more focused, fine-tuned the laser the smaller the dots can be. Allowing you to pack more of them and therefore more data onto a disc. To overcome the limitation of how focused the lasers can be, Min had a plan. Instead of using one laser to write on the disc, how about two?

Min Gu

The wavelength of the second laser beam, or the colour of the second laser beam is slightly different from the first one. So in that case, we also make the second laser beam into a doughnut shape. So imagine that one laser beam is a bright spot in the centre, the second laser beam is a ring structure. So then we use the second laser beam to erase the ring of the first laser beam.

Nick Petrić Howe

You can imagine this process a bit like this. If you shine a torch — a flashlight — on the wall you will have a bright spot at the centre and diffuse halo of light around it. But if you block this halo, you’ll be left with just a bright spot.

Fundamentally the same thing is happening here, the team used the second laser to erase the diffuse ring created by the first, leaving just a single focused laser spot. This allowed Min and the team to get around that diffraction limit and be able to write more information onto a disc.

Now, this laser-cancelling-laser technique has been around for a while, it has been used for etching tiny details onto things like computer chips. In fact, Min himself proposed its usage for data storage 10 years ago, but the key to getting it to work has been finding the right material. In this paper, Min and the team have created a thin film that can be coated on plastic disks and has the right chemical composition to allow the two lasers to write onto it effectively.

Min Gu

We tried many material, but we never reached as good as results liked detailed in this paper.

Nick Petrić Howe

Their method was able to write way more dots onto a disc than any other optical discs before.

In the end, they were able to achieve petabits of storage on a disc the same size as a regular DVD — a petabit being a thousand times as big as a terabit, much bigger than currently available hard disk drives. Which would allow you to store a whole lot of The Lord of the Rings, in the highest quality.

By enabling massive amounts of data to be stored on a single optical disc, Min’s method could help reduce the space and the energy requirements of the massive data storage centres that are used to store the increasing amount of data we create as a society.

Min Gu

So if you think about the petabytes of data storage currently, if you use a hard disk drive, then basically you need a very large space to store let's say 1000 of disk — stack them together — and a lot of the cooling process because these disk produce heat. So, air conditioning costs 30% of the energy consumption of data centre. Now, you can actually using one disk to store equivalent amount of information.

Nick Petrić Howe

This is still some way off though. At the moment the process of writing and reading the discs is pretty slow, and whilst the storage of the discs could be energy saving, this writing process is quite energy intensive. The energy used is similar to that to write a normal optical disc… but with 1,000,000 times as much data, so a lot more energy overall.

At the moment as well, Min and the team use a specialist microscope to read information off the disc, so we’d also have to change our devices in order to read them properly. The DVD player you have gathering dust in the attic won’t be up to snuff here.

But if these problems are overcome, maybe discs will make a comeback.

<disk eject sound>

In this podcast piece, you heard from Min Gu, from the University of Shanghai, in China. For more on the future of discs, check out the show notes for a link to the paper.

Benjamin Thompson

Finally on the show, it’s time for the Briefing Chat, where we talk about some of the stories that have been featured in the Nature Briefing. And Nick, I think I’ll go first this week and I've got a story from Ars Technica. And it involves a fossil that has really had scientists stumped for almost 100 years because well they couldn't really figure out what it was. And now researchers have taken a fresh look at it, using, you know, cutting edge techniques, and they figured out what it is. Now according to their research, which they've published in the journal Palaeontology – it is a fake.

Nick Petrić Howe

Oh, so the end of that particular drum roll is it wasn't a fossil after all, at all. What was it then?

Benjamin Thompson

Okay, well, we're gonna go back in time here to begin with. So we're going back to 1931, the Italian Alps where this fossil was discovered, okay, that was a small creature, a lizard-like maybe sort of 20 centimetres long, estimated to date back to about 280 million years ago. And when it was described in 1959, it was given the name Tridentinosaurus antiquus and apologies to any Latin speakers out there if I've got that wrong. Now, it's quite unusual. Now I'm going to show you a picture Nick so you can see it and we'll put a link in the show notes so that listeners can see it as well. And it's a strange looking thing. It looks a bit like a silhouette.

Nick Petrić Howe

Yeah, it looks kind of like a frog that’s been run over or something like that. It looks very odd.

Benjamin Thompson

Yeah. So it has got all its limbs, there has got a tail as well. And for the longest time, this kind of silhouette was thought to be preserved skin. Okay, now, this is very, very rare indeed. I discussed that with Shamini a few weeks ago on the podcast about how difficult it is to find preserved skin in any sort of fossil, you have to have just the right conditions. And it was posited that this fossil is preserved the way that it is, because maybe it was caught in kind of a volcano blast or something like that, which seared, which charred the outside layers of its skin instantly. Okay, to lend weight to this there are also some plants found in the same region, which were preserved in a similar way. Okay. And so this is quite exciting for a lot of people in terms of, you know, figuring out the evolution of lizards and where it's sat on the tree of life and what have you. And it's been discussed for years, you know, researchers have been trying to place it on said tree, but it turns out that all of those efforts might be for naught.

Nick Petrić Howe

That's very disappointing for all those people who've worked very hard for a long time. I guess, what was it then if it wasn't a fossil?

Benjamin Thompson

Well, this is where some detective work comes in, then. So researchers, you know, want to try and answer these questions about what was this animal? Where did it fit on the tree of life? So they took another look at it using cutting edge science techniques, which weren't available previously. And so they did a bunch of things. In one instance, they shined some ultraviolet light on it, and this fossil kind of fluoresced yellow, but the plants found nearby they didn't fluoresce which is kind of an interesting red flag. And it turns out, actually, that this might not have been too unusual, because a lot of old fossils had a layer of varnish put on them to preserve them, okay, which isn't really done very much now. But varnish kind of does fluoresce. Okay, so that wasn't necessarily a bad thing. But the researchers wanted to appear beneath this veneer to try and look at the actual silhouette to see, you know, was this skin? What was it? What can it tell them about the animal? And they did a bunch of sort of chemical techniques. And they realised that the skin is actually black paint.

Nick Petrić Howe

You’re joking?

Benjamin Thompson

Nope, specifically a type of paint made from animal bones called Bone black paint, with some irony.

Nick Petrić Howe

So–so was this some sort of prank then? Or was this just an accident? And it happened to look like a fossil and people got a bit confused by it?

Benjamin Thompson

Well, that's a great question. And I think what's actually going on here historically, isn't clear. Now the researchers conclusion is that someone had just carved kind of a lizard shape in the rock, and then filled it in with black paint. And they've used a bunch of different methods to characterise this. Now, as for who did it, they suggest that this must have happened before 1959 when the species was formally kind of described. But as to who and when, I mean, that's one for somebody else on some sort of true crime podcast to try and figure it out.

Nick Petrić Howe

Well, I guess, you know, finding out that this fossil isn't a fossil is disappointing for some, but presumably, there's more science to be done.

Benjamin Thompson

Well, there's a lot to still learn about this fossil. And I think what's interesting is that some of it actually does seem to be real fossil, like there's a couple of leg bones at the back of the fossil that do appear to be fossilised bones. And the researchers say that they found a few little things that look like tiny scales on the back of this animal. So there is an identification to be had, it's gonna be really, really tough because these bones aren't very well preserved, you know, not necessarily the end of the story for Tridentinosaurus antiquus, okay. But I think what the researchers are saying is stop using this for any sort of phylogenetic analysis because it isn't what it was reported to be. And it speaks to kind of a broader problem – there are fossils that are fakes and that comes up now and again, right. So I think the researchers suggest that when fossils are described, there needs to be maybe really, really good reporting of how it was done of– of what methods were used to characterise it, to try and avoid situations like this in the future.

Nick Petrić Howe

Well, maybe some lessons there then for future palaeontologists who come across fossils like this. Thanks, Ben. For my story this week, I've been reading about something that may sound a little bit strange as well. It's about meat-rice.

Benjamin Thompson

Meat-rice, okay, I've got so many questions. Is this rice made of meat? Is it meat made of rice? Is it just the dish containing meat and rice? I mean, Nick, please define what meat rice is off the bat.

Nick Petrić Howe

So kind of yes and no, and yes to those questions. So this is a kind of hybrid food. So this is where researchers have grown muscle cells and fat cells on rice. So they've used rice as a scaffold in order to grow basically meat. And so you've ended up with this sort of strange (and listeners, be sure to check out the link to this) like this strange sort of pink looking rice, which is a combination of meat and rice. And this is reported in Nature.

Benjamin Thompson

Why have they done this?

Nick Petrić Howe

Well, that's a very good question. And there are a lot of efforts around the world to try and make lab-grown meat. We've talked about them before on the podcast. But these have some problems. If you try to make the conventional things that people try and go for like steaks or burgers, they're quite hard to form into the right shape, because you just have like a mass of cells that doesn't necessarily grow in the way that you would expect if you wanted to have a meat-like product. So that's part of it. Also, people aren't necessarily familiar with lab-grown meat and stuff, they may not be interested in it, they may not know what to do with it, they may not know how to cook it. So these researchers were trying to address those problems by making a product that people are familiar with, and that they could add a bit of meat to increase its nutritional quality and thus we get meat-rice.

Benjamin Thompson

When I think about meat protein, I guess it needs kind of a blood supply and so forth to grow. But are these just small clumps of cells that are attached to the rice grain? What are we talking about here?

Nick Petrić Howe

Yeah, essentially it's that, it's like a film of cells that has grown onto the rice. So what happens when you're trying to do this is you get your rice, you lay on it a little bit of fish gelatin, and a commonly used food additive which helps those sort of cells stick onto it and then you bathe the combination of cells and rice in growth media. And then the cells just sort of form this layer on top of the rice and you end up with this, as I say, sort of pinky rice looking thing.

Benjamin Thompson

So it’s not just a rice plant that grows and it has the meat on the outside of the rice. The meat is added separately by dunking the rice into it.

Nick Petrić Howe

Yeah basically that. So it's quite different from regular rice. Apparently it tastes a bit nuttier, and it was a bit harder. But it does increase the sort of protein content and the fat content. Not by very much though it has to be said. So this was around 0.01 grams more fat and 0.31 grams more protein. So in the future, the researchers are interested in trying to raise those numbers up. But nonetheless, this could be an easy way to increase nutritional quality of rice. And also growing it in this way is much cheaper than other alternatives. Like, if you, well, if you grow just normal beef, that costs quite a lot, and also has an environmental cost as well. And compared to other lab-grown things, this could be a cheaper way as well, because you're just using the rice as a scaffold rather than trying to make a whole mass of lab-grown meat.

Benjamin Thompson

I don't know this is addressed in the article, but does it talk about how you need to cook it? Because I can imagine if you cook the rice, then you'd overcook the meat. But if you cook the meat so it’s right, then you'd under cook the rice? Is that something that's been addressed?

Nick Petrić Howe

Yeah, exactly. So this is actually one of the things that they wanted to make easier for people. Like how to use this in their cooking. And you cook it just like normal rice. So it goes a little bit yellow in places. But otherwise, you just cook it just as you would normal rice.

Benjamin Thompson

I mean, I guess it's quite an involved process to make this which suggests that we're not going to see it on supermarket shelves or supermarket fridges. I'm not sure anytime soon.

Nick Petrić Howe

No we're probably not like there was still work to be done with this. And also, lab-grown meat has not been approved for sale in most countries, only the US and Singapore have approved the sale of it. And so it seems that lab-grown meat still has a way to go in terms of regulation as well. But the researchers behind this we're quite excited and one researcher who wasn't involved as well says the idea seems really cool. You can just have one rice and take care of everything in terms of sort of nutritional needs.

Benjamin Thompson

Well, that is a neat one and I think it's starting to make me a little bit hungry. So let's call the Briefing Chat there for the time being before my stomach to rumble. And listeners, for more on both of those stories, head over to the show notes where you can find links to them and a link on where you can sign up to the Briefing to get even more stories like them delivered directly to your inbox.

Nick Petrić Howe

That’s all for now but check your podcast feed later this week as there’ll be an extra podcast of whale- like proportions. For now, though, you can keep in touch with us on X, we’re @NaturePodcast, or you can send us an email to podcast@nature.com. I’m Nick Petrić Howe.

Benjamin Thompson

And I’m Benjamin Thompson. See you next time.