eLife Episode 43: Is science getting harder to understand?
In this episode we hear how scientists have discovered that muscles play a role in controlling the brain's body clock; how circumcision rates among men at risk of HIV can be increased, and the monkeys that use tools to feed a seafood habit...
In this episode
00:36 - Are science papers getting harder to read?
Are science papers getting harder to read?
with William Thompson, Karolinska Institute
Are science papers getting harder to read? William Thompson tells Chris Smith why the increasing use of scientific jargon is affecting intelligibility.
William: We were four PhD students frustrated about reading different scientific texts. We had journal clubs together and there was specifically one person that we were reading repeatedly that we thought was hard to read. We joked originally, has this person always been hard to read or is this something which is developing as the ideas have developed?
We realised we could quantify this, and as soon as we realised we could quantify it for one person, we realised we could apply the same tools and get a much larger corpus, which was over 700,000 scientific abstracts. So once we realised this, we thought it would be really interesting to work together and make a study together and explore this question.
Chris: So what did you actually do to do this study and what bounds did you set on it?
William: We made a list of 123 highly cited journals from 12 different fields that could be downloaded from PubMed because those were the tools we made to download the abstracts, then we tried to quantify the readability of each abstract. So, for example, the number of words per sentence and the number of syllables per word and tried to make an estimate about how hard it is to read.
Chris: What time frame did this span?
William: The earliest article was 1881, but most of the scientific literature started to appear around 1960 that we could get our hands on and then up to 2015.
Chris: When you run the text from those abstracts through the analysers and ask it to score the language that’s being used, what trend emerges?
William: As I eluded to before, we thought the texts were hard to read and we found a large downward trend in readability, and that means that texts are getting harder to read now compared to previously which wasn’t too surprising for us but we were surprised by how strong the trend was. This trend was very strong downwards.
Chris: You looked at a whole raft of different journals which means that you could consider different scientific disciplines. So, are any disciplines particularly prone to this or is it that all scientists across the board now have a tendency to over complexification and use of long multisyllabic words where simple terms might actually be feasible instead?
William: I think the important take-home message was that all the fields we looked at were getting worse. There were some differences, for example, clinical medicine was the least worst, and molecular biology was the worst in one of the metrics. But I don’t think the emphasis should be placed on that. I think the emphasis should be placed on all fields were getting worse.
Chris: How do you account for this?
William: With the data we had, we tried to explore two possible reasons: one of them was: did the number of authors impact the readability because the number of authors has been growing over time. You often see four or five authors on a paper today, where in 1960 it was one or two. The number of authors does have an impact on the readability so if there’s more authors it’s generally less readable, but that doesn’t explain the trend.
Chris: Do you think it’s a case of ‘too many cooks spoil the broth’ a bit then, if you have multiple authorship? Too many people pulling in too many directions.
William: Exactly. I think we actually had that term in the paper.
Chris: Nonetheless, it’s not a strongest driver because even though you're seeing an effect, there’s still, over and above that, a strong signature of increasing complexity and inaccessibility with time regardless of the authorship number.
William: Yes, exactly. So, an additional hypothesis we had was that scientists may be drawing from an increasingly common vocabulary. We tried to see what were the 3,000 most common words that scientists use and we found that these 3,000 words were increasing overtime. Then we split this list of 3,000 words up into several categories to isolate a category we called “general scientific jargon.” And these words were on the increase. So, scientists are using more of a common scientific language which we called ‘science-ese’, drawing from this vocabulary of general scientific jargon.
Chris: Do you think it really matters though that some papers are a bit impenetrable because some people could argue, “Well, I’m a molecular biologist and it means something to me, and I don’t really care that much if an astrophysicist can’t read my molecular biology paper” and vice versa?
William: I’m very sympathetic to that view but, at the same time, this entire endeavour started when PhD students within the field of neuroscience were having a hard time reading some neuroscience. So it can hamper people within the subject itself. Then, in a much wider context, interdisciplinary fields are very, very important. Otherwise, you can have certain method developments which occur in one field which could be very useful in another field and that cross talk between subjects usually leads to greater scientific progress. So, being completely impenetrable to other disciplines is problematic.
And finally, science is not just for scientists. People should be able to use scientific knowledge to make society better. If the wider parts of society cannot access papers such as scientific journalists or policy makers, if they’re having a hard time interpreting or understanding scientific text, that’s going to mean that science can’t be used as effectively in a wider context.
06:44 - Muscles control the body clock
Muscles control the body clock
with Chris Ehlen, Moorhouse School of Medicine
The 2017 Nobel prize for physiology or medicine was awarded for research on the biological rhythms that dictate the lives of all of us. The circadian clock ticks chemically and genetically in every one of our cells, matching metabolism and growth to the demands of the time of day. And our understanding was that the brain contains a master clock - a cluster of interconnected nerve cells called the suprachiasmatic nucleus - and these use hormones and nerve signals to set the times of all of the “peripheral clocks” elsewhere in the body. So imagine Chris Ehlen’s surprise when he accidentally discovered that if you knock out BMAL1 - one of the genes that runs the clock - in skeletal muscle cells, the brain can’t keep time properly until it’s restored. Chris Smith heard how...
Chris E: BMAL1 is a core circadian clock gene. There's a molecular circadian clock in all our cells that keep time and BMAL1 is necessary for that clock functioning. But we really didn’t know how it was involved in sleep. So we had this mouse where BMAL1 was removed and what we did was we put it back. In one of the animals, we put it back in the brain. In one of the animals, we put it back in the muscle. The muscle was originally designed to be a control, but what we found was that it was only when we returned BMAL1 to the muscle that we saw normal sleep regulation.
Chris: It is bizarre, isn’t it, because the way in which we think that the circadian clock ticks is that there is this segment of the brain – the suprachiasmatic nucleus – where there is this genetic clock ticking which keeps time and we regard that as the master which then tells the rest of the brain and the rest of the body via various mechanisms what to do. And you're saying actually in fact, that some components of sleep might be originating from muscles.
Chris E: Yeah. You described that perfectly and we were very surprised, almost in disbelief. We really did expect to just return it in the brain and we would kind of eliminate the periphery as an influence and then go on and investigate where in the brain it would work. It turns out that muscle is really critical to cause this sleep phenotype. We went on to conditionally knockout BMAL1 in the muscle. So we used an animal where we could deliver a drug and then BMAL1 would only be turned off in muscle and what we found out is that when we just knockout BMAL1 in the muscle, we also see the same kind of phenotype that we see in a whole body knockout mouse.
Chris: So this argues then that the brain isn’t operating in isolation in telling the body cells what to do. There is some kind of signal which is being regulated by the circadian clock ticking in muscle which is feeding back to the nervous system and telling the nervous system what time it is.
Chris E: Right. That’s exactly what we think and that’s one of the things we’re interested in is, what is this factor and how does it work?
Chris: Well first of all, before we explore what the connection might be between the periphery and brain, why do you think it has evolved like that? Why does the nervous system have this dependence on the periphery when it could have all the components of the clock work just in this cluster of nerve cells in the brain and not rely on the periphery?
Chris E: It’s always hard to kind of predict what evolution was thinking, but I think it really seems obvious that there are peripheral processes that sleep benefits. Benefits to the muscle and other organs, and that maybe there needs to be some communication from the periphery, telling the brain that, “Alright, it’s time to get some rest. We need sleep too.”
Chris: Do you think that this is the reason why people classically say that when they're psychologically tired, they don’t sleep as well as when they're physically tired?
Chris E: That could be true, yeah. That’s a great point and I actually had not thought of that.
Chris: So what is the connection then between what is going on in the muscle and the brain? How does the muscle talk back to the nervous system?
Chris E: That’s the question we’re working on now. Unfortunately, we don’t have answers. We know there are some factors released from muscle that can affect the brain. So we’re starting to look at low-hanging fruit so to speak, the factors that we know are released from muscle and communicate with the brain. But we are just in the beginning stages of trying to figure out exactly what's going on.
Chris: So putting all these together then, what are the implications of the fact that we seem to have a clock ticking in the brain, we’ve got parallel clocks all over the body, keeping time as well, but previously, unbeknown to us was that these parallel peripheral clocks appear to be influencing and critical to some of the function of the central brain clock?
Chris E: The biggest implication is that it is providing a whole new area for research into sleep regulation. I don’t know that there were many people looking in the periphery to really understand how sleep is regulated. We were in the dark about a lot of the factors especially in sleep homeostasis so the effect of increased waking and sleep pressure and how that was regulated. So, this opens up the possibility that a lot of these processes may lie outside the brain and so, it gives us another place to look. It also might explain some effects that we see. For instance, there's problems with sleep and ageing. We know that there's a loss of muscle mass with ageing. We know that some skeletal muscular disorders are associated with sleep phenotypes. So it could be that if you have muscle problems that might be part of what's causing the sleep problems that are associated.
12:41 - Raising the rates of circumcision
Raising the rates of circumcision
with Sema Sgaier, Surgo Foundation
Measures designed to improve public health have to serve several masters: you need to change the behaviour of the largest group of people possible, and you need to do it in a way that’s cost effective and time efficient. Traditionally, providers have adopted largely a one size fits all approach but research by Sema Sgaier suggests that, when you do this, the message is lost on large sectors of society. Instead, she’s investigating the use of a process called “psychographic-behavioral segmentation” that uses machine learning to divide the population up into groups that need to be targeted a specific way. She’s looking at how to maximise the uptake of circumcision among men to prevent HIV infection. She explained the strategy to Chris Smith...
Sema: Voluntary medical male circumcision is an HIV prevention intervention, a pretty effective one that has been prioritised in 14 eastern and southern African countries. It’s a one-time intervention and it’s highly cost-effective in settings where HIV prevalence is high and male circumcision prevalence is low. By now, the community had circumcised about 12 million men. This was 8 million short of the 20 million circumcisions that was set as the global target. And so really, the goal here was how do we bridge the 8 million gap? The typical approach is that we were using, building awareness, and having a one-size-fits-all approach was not working.
Chris: Because there's a lot of diminishing returns, isn’t there? You end up to get the last few percent, you have to spend more and more, and more to get there. But you could make the intervention strategy far more cost-effective and far more rapid if you know who to go after, who’s most susceptible to the message and target them first.
Sema: Absolutely. You're absolutely correct. So, we were getting what we called the low-hanging fruit – those were that were already committed, that were ready, that were younger, easier to circumcise. If we look at the trajectory, the trends of circumcision, basically, it’s been getting harder and harder. And so, we have to be much more nuanced and we have to be much more targeted in what we do to be able to spend our dollars in the best way.
Chris: Of course, one point about this is that you need to know who those groups are or you need to know who the people are who are susceptible to which messages so that you know who to go after.
Sema: That’s right. So, we did a large scale study in 2 of the 14 countries, specifically in Zambia and Zimbabwe to really be able to determine these psychographic behavioural segments. Essentially, the first phase was a qualitative phase. The goal of that phase was really to understand the full set of internal factors that drive men to either circumcise or not. After that, we did a large scale quantitative study of 4,000 men in each countries where the factors that we identified in the qualitative study were measured extensively. And we used machine learning algorithms on this data to be able to develop groupings or segments of men.
Chris: And why is this a breakthrough in this particular space because insurance companies know this, people selling chocolate bars on television know that there will be subsets of the audience that they're going for? So, why is it a big step forward in this context?
Sema: In this context, we have been so-called segmenting people. I mean, there is the notion that people are different but it’s mostly been on demographic factors. So, we think of people as young versus old or urban versus rural, or rich versus poor. This idea of really being nuanced on what's driving choices and behaviours has not been common practice.
Chris: What were the segments that you highlighted in the two countries and were they indeed the same?
Sema: So, in Zimbabwe, we identified six segments and in Zambia, we identified seven segments. They're were quite different especially on the internal factors such as the beliefs and motivations. I’ll give you an example to illustrate that. So in Zimbabwe, two segments: one is the ‘enthusiast’ and this is just a name we gave them and another one is the ‘scared rejecters’. The ‘enthusiasts’ are quite motivated when it comes to circumcision. They believe in all of the benefits. They emotionally associate with a sense of achievement when they get circumcised. But there's just one thing that’s holding them behind. That’s understanding how to manage the healing process and the pain. When we look at ‘scared rejecters’, these have very low motivation. They're mostly older, they're married. They believe in the benefits but they just don’t see that it’s relatable to them. They actually aren't much influenced by friends. So really, the people that they're mostly looking up to are healthcare providers. And the they're really concerned about the pain, the possible infections from the procedure, and really want much more additional information.
Chris: If one looks at where is the HIV risk, which of those segments has the highest risk? And therefore, when you do a sort of cost-benefit analysis, which segment is worth targeting the most?
Sema: That’s a really good question. So, we were able to measure and estimate the risk of HIV and one of the things we saw is the risk to acquire HIV actually did not align with the likelihood of getting circumcised.
Chris: What does your result suggest we should be doing then?
Sema: First of all, it provides choices to the programme and also, insights for development of strategies to generate demand. So, more nuanced strategies if we wanted to get the ‘scared rejecters’. The typical approaches that we’re using now which is really around raising awareness and mass media is not going to work because these people are already pretty aware. What we need to do is really get them in touch with healthcare providers and have healthcare providers really do that interpersonal communication. In the case of ‘enthusiasts’, those men are mostly concerned with pain. And so, we need to really explain to them the pain aspect and how to deal with pain. The programme today does not talk about pain because there's been this understanding that maybe talking about pain has actually pushed men away. But our findings suggest actually quite the opposite.
19:04 - Genes in teats and placentas
Genes in teats and placentas
with Marilyn Renfree, University of Melbourne
What have a placenta and a marsupial mammary gland got in common? When scientists in America and in Australia compared the patterns of genes active in both, the answer is quite a lot. Chris Smith speaks with Marilyn Renfree, from the University of Melbourne…
Marilyn: A marsupial is a mammal. Like all mammals, it has hair and it lactates, but marsupials have been separated from other mammals for about 160 million years. They probably evolved in China, in Asia, there's lots of amazing fossils coming out of China. There's very few differences really between eutherian mammals and marsupial mammals except in their mode of reproduction. All marsupials give birth to tiny babies that then spend a long time – instead of in the uterus, they spend it in the pouch. So, a long time ago, I said that I thought that marsupials had traded the umbilical cord of the placenta for the teat because lactating is very sophisticated in marsupials. They're well-known for their amazing lactational physiology.
Chris: It might be a surprise to many people to hear you talking about placentas in the same sentence as talking about the word ‘marsupial’ because most people are of the opinion that tiny baby emerges, it goes on this teat in the pouch and that placentas have nothing to do with the equation.
Marilyn: Sadly, that’s an era that was made has been propagated in the public and in the literature for a long time where people just assume that marsupials have no placenta. That’s completely wrong and the placenta is the most variable structure in the animal kingdom. Every group of mammals has a different placenta that has slightly different structures but all of them function to transfer food and immune material across to the foetus to protect it. So there's really two ways – oviparous mammal, the mammal that gives birth to live young can protect their young. One is to keep them for a long time in the uterus which is what most eutherian mammals do and the other is to keep them for a long time in a pouch or a nest which is what marsupial mammals do.
Chris: So how have you explored this question that the umbilical cord has been traded for a teat in the marsupials then?
Marilyn: My fantastic colleagues at Stanford, they were able to use their fantastic facilities to look at the genes that are expressed in both placenta and in the mammary gland of marsupials or our favourite marsupial, the tammar wallaby and compare it to what happens in the mouse. Of course, there are many differences, but in the genes that Julie Baker and co. examined, they found a number of genes that were expressed in the placenta that were also expressed in the marsupial mammary gland. In particular, one called GCM1 and which is essential to eutherian placentation is in the mammary gland of marsupials. This is the first time this particular gene was found to be expressed outside the placenta, suggesting that this trade-off between umbilical cord and teat has been quite widespread and very effective in this very, very successful mode of reproduction.
Chris: Are there any other spin-offs from this study? Apart from insights into evolution, does it inform other aspects of how mammals work and reproduce?
Marilyn: Yes, I think it does because marsupial lactation is the most sophisticated in the mammal kingdom and marsupial milk changes dynamically through the whole of lactation. So in the case of the tammar wallaby, it’s a 9 or 10-month lactation period and the early milk is very high in carbohydrate so it’s sweet and very low in fat whereas the late milk is very high in fat and low in carbohydrates, and has specific proteins. So early milk is like human milk and late milk is like cow’s milk. What do we feed our infants but humanised formula of cow’s milk? In our studies showing transfer of young from an early stage of lactation where the milk is dilute to a late stage of lactation where the milk is high fat, we get growth acceleration and a lot of accumulation of fat around every organ of the body except for the brain. So we’re wondering whether this is giving us a clue to the early neonatal reprogramming that we do that may well affect later onset human obesity.
23:53 - Tooled-up monkeys drive shellfish to extinction
Tooled-up monkeys drive shellfish to extinction
with Lydia Luncz, University of Oxford
Humans aren’t the only animals to use tools. And nor, it would appear, are we the only group that risks, through the use of such tools, driving other species to extinction. Speaking with Chris Smith, Lydia Luncz has been looking at a population of macaques that use stones to harvest shellfish. As they deplete their stocks of prey, they’re changing their tool choices. And when the food runs out, the knowledge of that tool use will also most likely vanish…
Lydia: We were looking at stone tool use of macaques so we went to the Gulf of Thailand. There's a National Park called Sam Roi Yot National Park and the two islands are called Koram and Nam Sao. There are long tail macaques that live on both of those islands. One island, on Koram, it’s a bit of a larger island. There are a lot of monkeys. We have about 80 monkeys right now on this island and on the other island, there's just 8 of them.
Chris: What sorts of tools do these monkeys use?
Lydia: Basically, they forage for seafood. They love seafood just like us. So, when they crack open oysters for example, they use something that we call an axe hammer where they use the pointy tip of an elongated stone but when they crack open for example sea snails or crabs, then they use bigger stones where they used the flat surface of a stone. So, we can see by the tools that we find, the use that we find on the stone, what they actually have been eating.
Chris: And the overriding question you want to answer was what?
Lydia: So we went out there to those both islands. The first thing that became very apparent was that those monkeys on the different islands used very different sizes of stone tools and we wanted to know the underlying reason for this. Why would they select different stone tools for the exactly the same task? So we observed the monkeys and we collected our stone tools and then we explored their home range. So we collected information on stone availability. Is the same raw material available to them? And then we looked a bit closer at the prey that they target with those stone tools.
Chris: And what did you find?
Lydia: So we found that actually, the prey species on both islands were very different in size and that the monkeys were actually matching the stones that they selected to the prey size that was found on their island. So on the island where we had a lot of monkeys, we found that the prey species there was very small and also, reduced in number. So, they weren’t so abundant. And on the island where there was little amount of monkeys – just a few of them – we found that the prey population was flourishing. They were large. There were a lot of them there. so that was the main difference that we found between those islands.
Chris: And it’s your interpretation that on the island with lots of monkeys, there's a lot of pressure being brought to bear on what they're eating. And so therefore, you’ve driven down the average population size because your monkey is going to go for a big treat preferentially over a small one, so they picked off all the big ones. On the smaller island with fewer monkeys, there's less pressure. Therefore, there are more bigger specimens there. And to get the big ones off, they're using bigger tools.
Lydia: That is exactly what we found, yes. That was right. So, we look closer on the sexual organs of the prey species and wanted to know whether we find smaller prey, whether this had like an evolutionary reason. Because we see this, when humans exploit snails a lot, they become quicker in reproducing. So even when they're smaller, they're already able to reproduce. So we wanted to test that on our islands as well. And it turns out that they are not. So, the small individuals that we found on Koram island are not able to reproduce yet which means that the overharvesting of those shellfish must have happened quite quickly in the last decades. That means that the monkeys have harvested all the large individuals already and only leave the young ones that aren't able to reproduce yet.
Chris: If your intuition is correct then, the animals that are now exploiting the small prey would have in the past, had much richer pickings and big prey to play with and feed upon. So, were you to go digging on the beach for example, do you think you would find stones which were more in keeping with the other island where the prey is still larger and it’s a shift in tool use that’s happening, the animals are adapting their tool-use to the prey that’s available to them?
Lydia: Absolutely. that’s what we would expect if we would dig down to see what happened like maybe 20, 30, 40 years ago. We would expect that we also see larger stone tools with larger prey.
Chris: So, what are you concluding from this then? It’s an interesting observation. It’s a predictable observation borne out by some nice facts and evidence that you’ve been able to demonstrate here. But what are the implications of this?
Lydia: Well, maybe that every tool invention isn’t always going to lead to better and more advanced tools. That something maybe just ends in a dead end like those macaques. They're heading towards an extinction of prey on their island and which might have a detrimental effect to their survival, to their fitness. We think that stone tool use is socially learned in macaques. So we think that once their prey might be gone, that they will be left without the knowledge of how to use stone tools. And they're losing cultural behaviour that’s been around for hundreds of years.