Rebuilding Dinosaurs and Stress from Siblings
The ability to recreate dinosaurs inside computers means the true nature of the spinosaurus can now be uncovered, what the Afro Barometer reveals about the potential to use mobile phones to deliver remote health interventions, is intercropping being held back by using the wrong seeds, and signs that firstborns suffer seven months of stress when a baby brother or sister comes along, in bonobos at least. Join Chris Smith for the last look in 2022 through some of eLife's leading papers...
In this episode
00:43 - Spinosaurs did not swim
Spinosaurs did not swim
Paul Sereno, University of Chicago
The era of digital palaeontology means that guesswork and speculation about the size, speed, habits and preferred habitats of dinosaurs and other ancient animals is rapidly being replaced by objective computer-based reconstructions; and if you're really ready to become the next Indiana Jones, you can even do all of that during your expedition, as Chris Smith hears from Paul Sereno...
Paul - My name is Paul Sereno. I'm a palaeontologist at the University of Chicago. I've just come back from an expedition to the Sahara, one of my favourite haunts. We found 35 tons of wondrous things from the past.
Chris - Did I hear that correctly? 35 tonnes!
Paul - That's correct: 35 tonnes. It's an enormous quantity of material because some of the dinosaurs are large. And so we went to five different time horizons in the country of Niger, in the heart of the Sahara as part of the country, and they have the best and the deepest record of dinosaurs. And among our finds is the subject of today's podcast: Spinosaurus. We found new materials - very exciting material - from Spinosaurus.
Chris - Describe then if I were wandering around and I wouldn't be, but if I could go back in time and wander around at the time of Spinosaurus, A) how far back would I have to go and B) how would I spot one?
Paul - Well, <laugh>, you hope you spot it before it spots you. But you'd go back about 90 million years that time, which is what we call the late Cretaceous period. This part of Africa was a lot wetter than it is today. So we found petrified wood and giant fish. There were rivers and forests. There'd be a lush habitat and there'd be this triumvirate of predators that you'd want to keep an eye out for it because each one of them could do you in. The biggest of them is Spinosaurus not far behind is Carcharodontosaurus, blade shaped teeth on that one. Spinosaurus, a fish eating dinosaur. But there's a third one rarer, but dangerous and a little bit smaller. And that's an Abelisaur. And so these three predators, we find them for millions of years in Africa. We have nothing really like them living in the same period of time in North America. This, this is T-Rex territory in North America. Africa is a totally different dinosaur world.
Chris - So were they like T-Rex then, these spinosaurs?
Paul - No, Spinosaurs were not like T-Rex other than they could do you in, they really had a fish eating skull. But they, if they wanted to go after something else, they'd do it with their hands. Their forelimbs are among the strongest of any bipedal dinosaur. They are four feet long or five feet long with sickle shaped claws. They had a snout that was really designed for going into mud, going into the shallow waters after a wide variety of large fish. That was clearly their mainstay, their specialty, but they were big enough to take anything down.
Chris - So they walked around on two legs, but were pretty good with these forelimbs, which they could use for fishing, but they could also use their face and snout for that.
Paul - Absolutely. And the eLife paper was, I think, settling the question of whether they were four legged on land or two legged. We actually spent a lot of time on that. We tried to work on where the centre of mass was with a better reconstruction of the skeleton. And we find that it's not a fast moving dinosaur on land, but it is like all the other theropods on land bipedal or two-legged.
Chris - How did you work that out then? Because, presumably, what you've got to go on are skeletal remains - fossilised remains? (Exactly.) How did you then turn that into something that tells us this was a two-legged creature and this is how it moved. This is what it would've done?
Paul - Look, this is the age of digital palaeontology. And for all the young folks out there that are listening to this, this is your time to get into palaeontology. This is a digital age, and so even in the field, we were able to scan the fossils by stereophotographing and put them together while we're sitting in our expedition tent! Literally a few weeks ago, we were able to look at and, and, and move our Spinosaurus bones around. So what we did in the paper was, yeah, we start with the fossils and then we reconstructed Spinosaurus better than ever before by connecting the bones into the skeletons, making sure they we're all pieced together correctly. Then we looked at modern animals, CT scans of modern animals to understand how much flesh we should put on this dinosaur. And we're surprised that we had made mistakes before and papers had made mistakes.
Paul - The tail needs a lot more muscle on it than had been previously put on it because we looked at alligators, large lizards, they have a lot of muscle on the tail. It goes beyond the bone. And so when we did that, and then we checked out digitally, where was the centre of mass? Where would it balance over its time limbs or would it need its forelimbs to progress the land? The answer was, was definitive. It balanced over its hind limbs. Then we put it in water to see how and how well it could swim, what the forces were against the body with a big sail. This was an awkward animal to be swimming in water. And we proved that by putting it in water digitally, seeing where and when it would float, and then what it would do underwater, how fast it could swim.
Chris - When you say it's got an awkward sail, do you mean sort of on its head, on its tail? Where was the sail tissue?
Paul - So people are very familiar with Spinosaurus and the sail. It's actually not one sail. It has three sails. There's one on the head, a small one in the midline, then there's one on the neck that sort of pops out. We discovered after reconstructing it and then it goes down again. Then the big one is on the back. And these are bony crests covered probably with colourful flesh, but they were stiff bony crest. Now you don't want something like that in water and nothing that swims in water has anything like that. A sailfish, for example, which has a sail, it's retractable and when it wants to swim, and it's one of the fastest swimmers in water, it pulls that down. When it wants to break, it pulls it up because it operates as a break. It, it, there's nothing in water that looks like a Spinosaur for good reason the lizards that look closest to Spinosaurus with the big back sail. They don't use it in swimming and they're not aquatic swimmers. And so we think we've, we, we've fairly tracked down every conceivable line of evidence to test this idea of whether it was an underwater diving, marine predator or whether it was, was in fact a shoreline semi-aquatic animal that liked the shoreline like crocodilians and also was capable of walking on land on two feet.
Chris - So had people previously kind of cherry picked the evidence a bit and made it fit together to make a nice story. This thing's got these sail structures. They looked like they'd work in water. It's got a fish eating head. Therefore it was probably an aquatic dinosaur that occasionally went on the land and, and that was the story they built. But you are saying if you do the digital palaeontology and put it in water, it just doesn't float. It does float too much. It doesn't swim. It doesn't work!
Paul - You're, you're right. The idea, I, I believe that we have formally sunk the idea with this paper, but we're open to challenges. That's what science is about. Look, science is about arguments. And when the first bones of Spinosaurus came to light, they were, they were controversial. And the German scientists who described these a century go from, from Egypt, they were all destroyed in the, in, in the world wars that we've had. And we have refound their bones. When he described it, he described it as a fish eating dinosaur, and he was very careful and conservative and accurate, but he didn't have enough of the skeleton. And when we found the skeleton, I made the argument that it was semi-aquatic and then subsequently a tail was found and the tail had a big sail on it as well. And so the, the back sail actually continues on the, the tail.
Paul - And we find now that the predecessors of Spinosaurus, one that I found in, in Niger earlier in time Suchomimus, they also have this sail on the back and it continues to the tail. And the idea came, well, maybe he was using it as a paddle. And this got to be very popularised in the last few years: it was an aquatic dinosaur diving and swimming with the tail. And so we put that to the test and and the test says, "sorry, its sail was for advertising like a billboard on land and it could wade into water". It can go into six feet of water. We show on the paper before it floats. But float this boat was gonna happen, because it's lighter than water. It has a lot of air inside its vertebrae and it's very clumsy in water. So while it could - most dinosaurs and even humans can swim - we, we are not aquatic animals. And it is not definitely an aquatic predator. When you're an aquatic predator, underwater you have to - especially if you're big - you have to be good and you look like a whale, you look like an ichthyosaur you do not look like a dinosaur. And so we put this to the test.
09:31 - How many Africans have a mobile phone?
How many Africans have a mobile phone?
Sally Blower, UCLA
The potential of the smartphone to place a doctor within reach of people in even very remote or very poor settings means that we have an opportunity to improve healthcare delivery in places regarded traditionally as "hard to reach", both in economic and geographical terms. This includes many communities across the African continent. But how widespread is phone ownership in Africa? That's the critical starting point for any intervention, so operators can predict whom they can, and more critically whom they can't reach this way. Speaking with Chris Smith, Sally Blower, at UCLA, has been looking at data collected from 33 African countries to try to form a picture of where the gaps are...
Sally - In these resource constrained countries there's very poor healthcare infrastructure and many people live far away from healthcare facilities, so they have to walk long distances. Having Mhealth interventions in which they can call in with phones means there'll be better healthcare and people who live far away from it will have greater access to healthcare.
Chris - I must admit, I mean, I've travelled in Southern Africa quite extensively. (Yes). Most people I've bumped into in rural Africa tell me they would rather go without food than charge for their mobile phone.
Sally - Exactly. It has become an increasingly important part of life. People use it for business, agriculture, education and government health services. For many, for during Covid many people, if you required vaccination, wanted vaccination, you had to go in using your mobile phone to access the services.
Chris - Well, that would suggest then that actually uptake is pretty comprehensive. Is that what you found?
Sally - We found it as pretty comprehensive in that about 80% of people in the 33 African countries we looked at have access / own mobile phones. About half of these people own smartphones, so they have access to the internet and the other half own basic phones. But there's a huge difference among the 33 countries we looked at. And obviously if 80% own it, there's 20% who don't. And that's quite a large percentage of people.
Chris - Yes, indeed. Also though, is that 80% of the population as a whole, but when you look at the stratification of that population, a hundred percent of kids and a smattering of middle-aged people are no elderly people or is it pretty generalised across? How does it break down?
Sally - There's a lot of inequity. When it comes to age. Most of the phone owners are because of the demography of Africa, most phone owners, mobile phone owners are under 30. And they tend to own smartphones. People over 30 tend to own basic phones.
Chris - So that would argue then that we have actually got a problem in some respects because most people in most countries, most of the time access healthcare when they're older.
Sally - Exactly. So the obviously for women in antenatal care, that will be younger women generally, but yes. For healthcare that, that's correct. And then we've got, we found great inequities into who actually owns phones, mobile phones.
Chris - In what respect?
Sally - Well, there are great gender differences. So men are twice as likely to own mobile phones than women. And we found urban rural differences. People living in urban areas are about three times more likely to own mobile phones than people in rural districts. The age difference I've mentioned and wealthy that the poorer you are, the less likely you are to own a mobile phone. Though we did find some interesting differences in that some people who are very poor do own smartphones.
Chris - I was going to say, is this just a function of wealth? Because a lot of those factors do really co-locolise with people who are likely to be in work.
Sally - Yes, it does. It does depend a lot on wealth, but wealth can be men and women in a couple can have the same level of wealth, but still the man is likely to own the phone and the woman is not likely. So it's not a simple function.
Chris - This is quite fine grained data from 33 countries. How did you do this?
Sally - So we got we got the data from a database called Afro Barometer, and this is a public opinion data questionnaires that are collected throughout 33 countries in Africa. And basically they collect social, social data on politics and economics and governance, but they also have one or two questions on mobile phones. So that's why we chose to use that database.
Chris - And what are the implications of this then? I mean, I know we started this conversation by looking at the, the reason why this matters in terms of doing health interactions and so on, in resource poor settings. But give them what you've now found with this data in hand and these results. How does this guide, change or have implications for what we do about these health interventions over mobile devices?
Sally - Well, I think the thing about the mobile health interventions is they're being rolled out as pilot studies, so little studies to see if they work or not, if they're effective when they're rolled out at the large scale, what will need to be done is to address the inequities, the urban, rural, the gender, the age so that the people who are the most in need of these health interventions don't suffer from not attaining access to them.
Chris - Have you looked over time though, longitudinally at these data? Presumably this, this survey has been run more than once, and therefore a rate of change could be approximated. Is this a problem that will just take care of itself, it's going to fix itself and it's going to do it quite quickly? Or are these entrenched in inequalities that are not going to fix themselves and they do need active intervention?
Sally - Well, I do think a lot of them are entrenched. You're quite right. The survey has been conducted. This was the seventh wave of the survey and mobile phone usage has been growing over time. Whether it's going to continue to grow or not depends on what's happening in Africa. Obviously with the urbanisation that's happening in every country, that suggests that greater wealth and more people would own smartphones. However, the same is, is happening, uh the other way that in rural areas people are getting poorer. So it might be that mobile phones grow, but that most people are buying the basic mobile phones rather than smartphones. But that will be addressed, um more data are being collected and more data will be able to be analysed as time goes by.
16:56 - Monoculture crops unsuited to intercropping
Monoculture crops unsuited to intercropping
Laura Stefan, Agroscope
Modern intensive agriculture usually involves the mass cultivation of singel crop species, like a field of wheat for instance. But plants didn't evolve to grow in a monoculture, and forcing them in that direction might mean wwwe're missing a trick in terms of yields and environmental sustainability. So thinking is shifting towards to use of mixtures of crops - this is called intercropping - where multiple species are grown side by side and where certain characteristics of one plant can benefit another. But the seeds we're using to plant these mixtures have often been bred specifically to grow as monoculture crops, so might not be the pick of the bunch. Speaking with Chris Smith, Laura Stefan, who's at Agroscope in Switzerland, wanted to explore this, and find out whether intercropped species might evolve to become better bedfellows again...
Laura - We were working on intercropping. So when we grow more than two species together, and we were thinking that usually intercropping is done with commercial seeds, but that have been bred for optimal performance in monocultures, they have been selected for decades so that they would yield better in a monoculture. And so we thought maybe these particular seeds are not the best for mixtures because the plants would have to behave differently. So we wanted to see if the crop species had this possibility to adapt.
Chris - Before we explore that. Mm-Hmm. <Affirmative>, what's the reason that scientists, agronomists, farmers, producers, do into cropping? Why do that at all?
Laura - So it's a way to increase the diversity of agricultural systems and to get a bit out of this intensive very low diverse systems which are not very good for the environment. Intercropping can be also positive in terms of finding species that are complementary to each other, and so that will a bit help each other to grow together. And this can have benefits for productivity.
Chris - Would a simple way of looking at this be then to say, well, you've got two different species, so they're not competing with each other directly for all the same things. There will be some competition in some respects, but one might help the other. For instance, by putting something back into the soil that boosts the other one mm-hmm. <Affirmative> or one's a bit bigger so it gives a bit of protection to the one that likes a bit of shade. Is, is that the kind of relationships that can be garnered from these sorts of mixtures?
Laura - Yes. One very famous example is when you mix a cereal with a legume because the legume can fix nitrogen from the air and so the cereal will have more access to this nitrogen.
Chris - It stands to reason I suppose, because naturally plants evolve to grow in communities, not just a monoculture. And so what we do with agriculture really is to force them into a situation that they aren't that evolved for. And then we select for ones that can tolerate it and you are saying, well, well actually might there be a better way where in fact we, we don't do that and we look for plants that are better at growing in communities and and also whether there is an evolution as they do so.
Laura - Yes, that's exactly what we were trying to do. We started with an intercropping experiments where we had six species growing in monocultures but also in mixtures of two and four species. And then we took these seeds at the end of the first year and the second year we planted again monocultures and mixtures, but each time with seeds that were either coming from the monocultures or coming from the mixtures.
Chris - And what were you measuring? What was the outcome? Was this yield or other growth parameters?
Laura - Yeah, we measured productivity, so biomass and yield. And we also measured some classic plant characteristics along the way.
Chris - So what you'll get at there is whether or not having a monoculture and then putting that into a community is less good than having a community, getting the seeds from that and then growing that again in a community. (Yes.) And seeing if there's some kind of evolution or development or, or benefit that comes from that.
Laura - Yes. We looked at a plant interaction index, which basically allows you to tell whether the plants in a community are more experiencing competition or facilitation. And we did see that when the seeds were coming from a mixtures, the plants were competing less.
Chris - How were they achieving that? Is that just because basically the ones that thrive and therefore the ones that set more seed and therefore the seeds you are more likely to plant are the ones that got on well in that situation, they were already there in the population? Or did that evolve and enrich with time?
Laura - The mechanisms are a bit hard to disentangle. So we thought over time the species would adapt so that they would use the resources better. We saw some indications of that the plants coming from a mixtures were, for instance, intercepting the light better than when they had a monoculture history, which sort of indicates that they learn to use the resources better over generations.
Chris - Fascinating findings. But does it translate into significant differences in yield and plant behaviour? Because if it's, if it's just lost in the noise in terms of what sort of a difference it makes, then we could probably say, well, it's interesting, but, but not of commercial benefit. But is it a big difference that you get
Laura - Practically so far, we did not show that there was a significant increase in yield, which does not mean that there couldn't be, because our experiment was quite short. It was only three years, so we only had two generations. We know that evolutionary processes are very long-term, so this might be that it didn't have enough time to happen properly. So of course this effect should be researched further.
23:39 - Firstborns stressed for 7 months by siblings
Firstborns stressed for 7 months by siblings
Andreas Berghänel, Veterinarian University, Austria
Firstborns, parents often say, behave quite differently from their siblings lower down the birth order. Science also agrees with them and dubbs the phenomenon the firstborn effect. But why should this be? Something about the early years, perhaps as an "only child", must be influencing the subsequent development of that individual. No one knows what, yet, but perhaps a sustained surge of stress hormones when a brother or sister comes along could be part of the answer. Speaking with Chris Smith, that's what Andreas Berghänel, from the Veterinarian University in Austria, has been finding in our close relatives the Bonobos...
Andreas - In the moment when there as a, a new sibling born, the older child can show a lot of stress behaviour. But what we never have tested so far was physiological stress levels. And for this we measured cortisol levels in, in urine sems. Cortisol is also in humans the most important hormone that regulates stress. We wanted to know if this also happens right at a time in a new sibling is born.
Chris - Do Bonobos show the same stress behaviour that humans do? Then when a new one comes along and you've still got one that's relatively young, do they behave the same way as a truculent human infant does when it gets a sibling?
Andreas - They show at least some more stressful behaviour. They try to get closer to the mother, for example, and stay more around.
Chris - So how did you test this?
Andreas - What we primarily did here was really looking for this stress hormone levels to cortisol levels for this be collected urine samples when the new sibling is born so that we can really have a look to the cortisol levels.
Chris - So it's a measure before the sibling comes along so you know sort of what the baseline is for that infant. And then you're measuring after the sibling comes along and to see do the stress hormones change their levels?
Andreas - Exactly. And we really did that also for long time. So not only right before or after that, but really years before and years after that for a really long time. So we could also have a look how long these increased cortisol levels stay at high levels after that.
Chris - And, and I presume from what you've just said that they do go up then there is evidence of stress in the older infant when the new one is born.
Andreas - Yes, indeed. We find a very extreme increase. So we found a fivefold increase in cortisol levels, which is something if normally you would like to stress an animal, let's say in captivity for whatever reason, then you would never get this kind of increase. So it's a really very strong increase that you could see there. And you could even see that this really high cortisol levels stayed out for about seven months after the sibling was born. So for several months they show very high stress levels.
Chris - And is that stress manifest in any other way? Because one of the other things cortisol does is it dampens down the immune system, doesn't it? So do the animals succumb to any other effects when this is happening to them?
Andreas - What we could also see, we also measured nerine levels, which is a kind of marker for the immune system. And that showed a decrease. So it seems that right at the birth of a sibling, the immune system decreases a little bit.
Chris - Was this true for both male and female infants or was one more affected than the other?
Andreas - We could see that in both. So there was no difference between males and females.
Chris - And were there any examples where this didn't happen in the infants or was it a comprehensive effect? Every single infant got this response and it stayed up for seven months
Andreas - On what we have seen. It was really exactly like this and each single infant, which was particularly impressive because the age at which and new sibling was born was very different between the infants. So we had some infants that are about two years old. When the new sibling was born, we had other infants that were more than eight years old. And all these infants we could see exactly the same cortisol reaction.
Chris - Do you think there are any long-term consequences of them having this happen to them?
Andreas - This would be a really interesting question. Periods of very high cortisol levels early in life can have very strong effects on growth rates behaviour later in life. So that's really a question. If this also triggers some changes and development and also even adult behaviour.
Chris - So if you have the Bonobo equivalent of an only child and they're not gonna be susceptible or subject to this big cortisol surge for a prolonged period of time, seven months, might that have long-term health consequences or, or behavioral consequences for those only children? Has anyone looked at that?
Andreas - This will be very important questions. So one thing that we know also from humans, siblings are the strongest early answers that we can have throughout life to under creator, also the strongest competitors that we have throughout life. So it can be both. Both can be benefit from each other. So at least on this letter, we know that having a child can have strong impact on the photo development and life. What it means to have these kind of high cortisol levels. I think we have no ideas of far. We really have to find it out.