Rebecca Coffey: Evolutionary tales and Just So Stories

Rebecca Coffey, image courtesy of Rebecca Coffey

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It’s no secret on this podcast that stories about evolution and the weird animal behaviours that can arise as a result are kinda my thing. And lucky for me, they’re also a favourite of our guest this week, Rebecca Coffey. She’s collated a selection of her essays into her book, Beyond Primates that came out earlier this year. So of course I took the chance to geek out with a fellow Darwin devotee, and I started by asking her why evolutionary stories fascinate her so much…

Rebecca: Well, I've always thought in terms of evolutionary psychology. You know, you observe behaviour even just growing up, and we all seem just a bit ape-ish or dog-ish or cat-ish, and so I've always liked wondering where certain behaviours came from. So I really came to it from a behavioural perspective, and I have just always been fascinated by it.

Sally: Is that why the book is called Beyond Primates? Because we are kind of ape-like, but with other behaviours? Or is it that you're looking at the stories that don't just include primates? 

Rebecca: Yes, I'm looking at those that don't just include primates, because lots of people just kind of dim down when they hear the word 'evolution', because we don't need to hear about Neanderthals all the time.

Rebecca: Right? And what I want them to appreciate is that fascinating signs of evolution are everywhere, and that the evolutionary tree is very wide and big and that in certain ways we have cricket-like behaviour, right? I mean, the idea is that this wondrous world around us has evolved accidentally from single-celled animals.

Rebecca: So if you remind people in a title that evolution is bigger than just where we came from, but where all of this came from. That's what I was reaching for. 

Sally: I think that's always been the thing that interested me in evolution and particularly evolutionary theory was once you kind of get your head around the fact that every single living thing, not just animals, but plants and fungi and bacteria, they're all related and they're all following the same... I say rules, but we know it's a little bit looser than your physics rules.

Rebecca: It's way looser!

Sally: But they're following the same kind of principles driving these different adaptations. And it's the fact that it's the same principles in every single aspect that can lead to such disparate and diverse behaviours.

Rebecca: Yes. Someone said to me the other day when we were talking about artificial intelligence, he said, "Well, really, nature is what's more intelligent."

Rebecca: And I said, "Whoa, whoa, whoa, whoa, whoa." Nature is dumb luck. Every step of this has been dumb luck. There's no intelligent driver, according to Darwin, anyway. And if you look at it that way, it seems even more miraculous to me.

Sally: And also to say nature is intelligent. What is nature? Assuming that there is this one monolith controlling it all. 

Rebecca: Exactly, exactly. 

Sally: Before we get too philosophical, I want to chat about some of the stories that you cover in your book, because I just think they're really fun to talk about. And I love what you were saying about how some people shut off when they're like, "Oh, it's a science book." No these are just fun, quirky stories.

Sally: So I want to start off with wasps. Now, I don't know about in the US, but in the UK people are not a big fan of wasps over here. But I think they'd be very surprised to know that at least one species, they can recognise each other's faces. They can recognise individuals. Tell me more about that. 

Rebecca: Well, what I love about that story is how they figured out that wasps could recognise faces. So what they did was remove some wasps from the nest, paint their faces, put a dab on their faces, put them back in the nest, and they got beaten up. They were not recognised as part of the community.

Rebecca: I love how simple some drivers of experiments can be. Let's just see what happens. 

Sally: What does a wasp's face look like? A lot of people won't have looked at a wasp close enough, they'll have run away at the first sign. 

Rebecca: They have kind of an upside-down pear shape. They have antennae coming out of their foreheads, they have very wide-set eyes and they have what look like gripping mandibles. I'm not even sure if that's what they are. There's an orange cast to the whole thing, at least what I'm describing here is a specific variety of paper wasps. 

Sally: Yeah, this is the Polistes fuscatus, so not the same as the common wasps you get here in the UK.

Rebecca: Right.

Sally: And you described how the researchers would paint their faces to make them look visually different, and then they were able to work out that this was a genetic thing.

Sally: How did they work out that there were genes involved in facial recognition? 

Rebecca: So, as you know, the driver of evolution is most probably environmental change or environmental pressure. And in this variety of wasp, there are several queens in each nest and they have all the babies. And all of the men are drones and inseminate the queens, so that's life in the nest.

Rebecca: The queens are always in a little bit of a tussle over dominance. Who is the most important queen? So being able to win these battles, remember which battles you've won, remember which battles you've lost, skills like that are important to their survival. That's the environmental pressure, the social pressure.

Rebecca: They're the only ones having babies, so whatever works for them works for the species. So they've acquired a little bit of visual memory. And when they have babies, their genetic information goes into the next generation, but they only have four or five competitors. So somebody who has more genetic luck than the others survives, and her genes sweep the population, right? They all become more like her.

Rebecca: So what the scientists did was look at the DNA, the long strings of genes, and they were able to identify specific genes that were responsible for memory and vision. And they found that the sequences of genes that were unique to this variety, they were long.

Rebecca: So, the idea is that over generations, there's genetic shuffling going on. There's just so many arbitrary evolutionary changes, some work out, some don't, that important gene sequences get increasingly shorter. Well, these were really long. And so that tells everybody that it is a recent change genetically that is most probably responsible for this ability to recognise faces.

Rebecca: Now, what drew me to this story, because I had been writing so much about human evolution, was that I was fascinated with...you know, we started out being human-like. We separated from chimps: six and a half million years ago was our last common ancestor. And about two and a half million years ago we became more human-like.

Rebecca: And suddenly, at around 35,000 years ago, somewhere between 15-35,000 years ago, we seem to have developed the ability to speak and to think about as well as modern humans. We became modern humans very quickly without a huge morphological change. Morphological meaning an observable difference. We looked the same, but suddenly we thought way better.

Rebecca: How did that happen so quickly? And this wasp research suggests that rewiring in the brain or a genetic shift in the brain can happen way, way, way, way, way more quickly than a gross physical change. So for me, it helps me understand how it is that we became thinking and feeling and talking humans able to imagine things that we've never seen before, able to create art that represents magical figures that we've never seen in nature. We became humans who could tell each other stories, who could imagine mutual futures, who could say, "I love you, and I can imagine us spending the rest of our lives together." We became fundamentally different, perhaps as quickly as wasps acquired the ability to recognise faces.

Sally: I love that your brain goes from wasps beating each other at their nest to humans declaring love for each other. I think that's a wonderful link, and I suppose because the mutated sequence, in comparison to its two sister species, the two most closely related wasps- because it's long now, doesn't mean that it's going to stay a long sequence forever, but that as evolution goes on, it'll get shorter.

Rebecca: Yeah, it will get shorter and shorter and shorter, like every sequence does. Like dumb luck makes it happen. I actually thought of titling the book 'Dumb Luck'. 

Sally: Maybe that's what we'll call this episode.

Sally: So, moving briefly on to humans before we then move into what's maybe more interesting, which is... single-celled fungi. I think everyone much prefers talking about single-celled fungi than they do talking about humans. But we'll start with the boring humans to begin with.

Sally: Listeners who listened to our bonus episode a few months ago from the Hormones Inside Story podcast about diabetes will have heard about the Dutch Hunger Winter and how that has affected diabetes rates. But for those that didn't listen to that episode, can you briefly describe what the Dutch Hunger Winter was? 

Rebecca: The Dutch Hunger Winter happened in the middle of World War II. The Nazis tried to starve out, and effectively starved out, a portion of the Netherlands. About 20, 000 people died, and those who survived got about 400 to 500 calories a day, and many were eating tulip bulbs. Now, imagine how hard that was on pregnant women who need an awful lot of food, and imagine how hard that was on growing foetuses.

Rebecca: What they eventually saw was that those pregnancies that made it through to term and resulted in live babies, an awful lot of them grew up to be obese and to die early of cardiovascular diseases. And one might jump to the conclusion that that was because maybe the mother had overvalued food after the starvation experience and so had fed everybody way too much, while their older siblings and younger siblings did not have the same health problems.

Rebecca: They were not obese, they were not dying young. So what was it about these kids that made them inherit something from an experience that was over and done with? So that opened up the larger question of epigenetics. So what epigenetics are is the idea of what happens, in addition to genetics, to control everything about us, to control our behaviour, our biology, our psychology.

Rebecca: So way, way, way back, six years before Darwin published "On The Origin of Species", there was a biologist, Lamarck, who had an idea called transmutation. And Darwin thought it was hogwash, and some of it was. He thought that inanimate objects could spontaneously become animate. He thought that cells aspired to greater complexity, as though there was an intelligence.

Rebecca: So these ideas are probably hogwash, but he also believed that there were heritable changes that had to do with experience that you could inherit the lessons learned by your parents from experience. And these days, there's a lot of chatter about how is it that trauma is passed on through generations? How is it that children of Holocaust survivors seem to hold on to some of the trauma that their parents experienced? Is that a biological process, or are they infected by trauma simply because they're being raised by fearful, traumatised parents? 

Sally: With Lamarck, it was very much like Rudyard Kipling's "Just So" stories. You can imagine a horse with a very short neck, and then it just stretched and it stretched its neck, and suddenly it grew a longer neck, and that's how the giraffe got its neck. Or the wonderful one of the rhino that took off its skin to go and have a bath in the mud hole, and then it was eating cake for some reason- if I remember my Just So stories correctly- and it got cake crumbs inside its skin, and when it put its skin back on, what was a beautifully tight skin, it scratched and it scratched until it became loose and saggy, and that's how the rhino got its skin.

Sally: And the idea being that something that could happen in one generation, through its life, would carry on. But when it comes to the Dutch Hunger Winter, they showed by comparing siblings that it wasn't just the attitudes and the culture of the mother- but what's not to say that it's not just, well, this foetus didn't get enough food during its life so it grew up malnourished? What's to say it's actually affecting the gene level? 

Rebecca: Well, there's been a few decades of work about epigenetics. And what seems to be the case, particularly in research with yeast- "epi" means above - and sitting on top of the genes, are chemicals that act as on-off switches expressing or activating the genes.

Sally: And these are physically on top of the genes? 

Rebecca: Physically on top of it. It's there. There's chemicals attached to the DNA and they allow genes to express and they can also act as volume control. So, is it on, is it off and how strongly is it? 

Rebecca: And so this scientist, Murat Acar, he's at Yale University. He took a culture of yeast. Now, yeast reproduce at an astonishing rate. In a day, they'll go through 14 and a half generations. And any one culture of yeast will be genetically identical, though there will be random differences in the chemicals that are sitting on them and forcing them to express or not express, and at what volume.

Rebecca: He was noticing the rates at which they metabolised sugars. And he separated out constantly the ones that metabolised the most, the ones that metabolised the least, and the guys in the middle, and watched them through generations and kept separating them out. And he noticed that the ones that were the most efficient never got better at it, and theorised that maybe they were really as good as they could possibly get.

Rebecca: The ones in the middle stayed about the same because chance would have everything drift to the middle, and the ones who were the worst got progressively worse. But there was no genetic change happening. 

Sally: How did they know that? 

Rebecca: You can look. You can look at the gene level, and there were no genetic changes happening.

Rebecca: So they were epigenetic changes and he was able to over subsequent experiments show that it was happening again and again and again in a steady pace, that the worst got worse and the best didn't get any better. 

Sally: So normally we think of the code of DNA, the A's, T's, C's and G's, the letters being passed on.

Sally: Now we know that there's another layer literally on top of it, these chemicals that are stuck onto the DNA. Although my DNA is half my mother's and half my father's, most of the physical, chemical strands of my DNA - I made them my cells. So it's not like those same chemicals hitched a ride to me, so how come I've got the same chemicals stuck to my genes that happened during my parent's lifetime?

Rebecca: The common thinking is that these chemicals stuck to the top of your genes can get stuck in their on-and-off positions. So experience puts them somewhere, and they can get locked in. And then it goes down into the next generation. And, of course, in the next generation, experience can change that. But unless a strong stressor comes along, you have a permanent change that is epigenetic. 

Sally: So if we go back to the people in the Netherlands. We know that the women who were pregnant during the famine probably experienced this change. We know their children did. I suppose the big question is, what about their grandchildren?

Rebecca: It seems to be a permanent change. They seem to have inherited something from their mother's experience, and it seems to be a permanent change. 

Sally: And then you mentioned that this was sort of an idea that Lamarck had in his head, and Darwin poo-pooed it. Does this mean, I mean, the big question that people will want to ask is, does this mean that Darwin was wrong if I was to sensationalise it?

Rebecca: Darwin didn't understand everything. Darwin certainly got the whole dumb luck thing right. But there were little things that he missed. For example, he did figure out that natural selection requires sexual selection. Right? That in order to pass your genes into the next generation, you have to talk somebody into wanting to mate with you.

Rebecca: And so, bluebirds are deeply blue, the males and the peacocks are wildly feathered, etc, etc. So he got it about natural selection, the importance of passing your genes into the next generation. He got it about sexual selection, visible changes that make you more attractive to a mate. What he didn't get was a subset of sexual selection.

Rebecca: That is sperm competition. What happens if mating isn't enough? What if that female mates with somebody else five minutes later? What makes you think your sperm is going to get to her eggs? When, you know, everybody else is mating with her and they have sperm too. So he didn't understand that sperm competition was a subset of sexual selection, which is a subset of natural selection.

Rebecca: He didn't get everything right, but he got the dumb luck thing right. And that is world changing. 

Sally: And in all your years doing this science journalism, you must have come across so many, fun stories, bizarre adaptations. Is there any one that just kind of sticks in your head, like is your go-to dinner party story of, wow, isn't this just incredible?

Rebecca: Well, my favourite story these days is a sperm competition story about the Malabar spider. So the Malabar spider's problem is the females take many mates. And so the male has the same problem that males throughout the world have, which is to make sure that his sperm gets to the egg before the other sperm gets to the egg.

Rebecca: Now, she has a hundred eggs or so in there. So if he can fertilise that, he's sending lots of babies with his DNA information into the next generation. So it's quite a prize. So, first of all, she's three times as big as he is. He has his sex organs dangling from his face, and he approaches her and he puts one into her receptacle. And it starts to ejaculate and once it's going, he gnaws it off and leaves it inside her where it continues to enjoy the sex.

Rebecca: He comes out, and he stands ready to fight off any other male who comes. Now, she actually has two receptacles, but fortunately he has two sex organs, and you would think that he would go over and plug the other one with his other sex organ. But no, he devours his other sex organ. And then, having grievously injured himself, goes on to battle the other male.

Rebecca: So why? So, a bunch of scientists in Europe and Asia tried to figure out why, and they set up battles between male Malabar spiders. They put eunuchs against eunuchs, eunuchs against partial eunuchs, spiders that had one sex organ left, and eunuchs against fully able Malabar spiders. And the name of their paper says it all, and it is, "Eunuchs are better fighters". For some reason, having grievously injured himself, he can fight way better than anybody else. And then... After this, he offers himself as food to the female. Now, what sense does that make? Well, he just inseminated a hundred eggs or so. She needs food. And he has no more reproductive potential.

Rebecca: And according to Darwin, that's really all animals are interested in. And so he may as well be dinner. 

Sally: And that's the story you pull out at dinner parties! 

Rebecca: It is. It is. I don't get a lot of invitations.