S3.10 Out of Africa: uncovering history and diversity in the human genome
Kat: Hello, and welcome to Genetics Unzipped - the Genetics Society podcast with me, Dr Kat Arney. In this episode we’re taking a virtual trip to Africa to explore the genetic diversity in the birthplace of humanity, discover how researchers can read the cultural and historical stories written in the genome, and discuss the implications for the lack of diversity in our current genetic databases for global health.
Before we start, a quick plug for Ingenious - my recent five-part series on BBC Radio 4, produced by the brilliant Beth Sagar-Fenton, looking at the stories (and some of the science) behind five of my favourite human genes. There’s the Ginger Gene, the Breast Cancer Gene, the Milkshake gene, the Alzheimer’s Gene and the Cyclops Gene - also known as Sonic Hedgehog, the best gene of all time, in my personal opinion.
Sarah Tishkoff - African genome explorer
Who are we? And where did we come from? These are big questions, and Sarah Tishkoff from the University of Pennsylvania has dedicated her career to researching the genetic story of humans in Africa - the birthplace of our species.
I sat down with her for a chat during a break at a conference on human origins and evolution, held at the Wellcome Genome Campus in Cambridge at the end of last year, to find out what got her interested in exploring the genetics of African populations, how she carries out her research in an ethical and culturally sensitive way, and what we can learn from these incredibly diverse human genomes.
Sarah: First of all, we can only look at the diversity in modern populations and those are the ones who survived until today. So, there could have been populations that were there tens of thousands of years ago and they didn't make it until today. For that, we're going to have to rely on the paleobiological record and someday, we hope, ancient DNA from Africa. Right now that's a challenge because the DNA degrades, it doesn't hold up well in that environment.
From looking at modern populations, we can make inferences about; when did populations diverge from each other, were there migration events between populations in the past? So, trying to deconstruct the relationships of populations in Africa today.
What that's showing us is that Africa has the most genetic diversity compared to anywhere else in the world. That makes sense because it is the site of origin of modern humans. Some relatively small number of humans left Africa somewhere between 50,000 to 80,000 years ago. They brought with them just a subset of that diversity in Africa.
But we've shown and others have shown that African populations were larger, they maintain more diversity, they've been larger for a long period of time and they've been very subdivided. So there's a remarkable amount of diversity between African populations, not just within populations.
The other trend that we see is that most populations are admixed, meaning that they show ancestry from different populations. That's because populations have migrated over long distances and they interbreed and then they migrate somewhere else and interbreed with the local population there, producing a very complex history.
Kat: As Adam Rutherford said, "Humans are mobile and horny."
Sarah: That's right!
Kat: So when you are trying to study the populations, the genetic diversity across Africa, there's a lot of people in Africa and a lot of different populations. How do you go about trying to gather that kind of genomic data? Because it's only relatively recently that we've actually been able to really get into studying whole genomes from a significant number of people at once.
Sarah: So, what originally motivated me was the linguistic data. That's what drove the questions. I was actually doing research in Johannesburg in South Africa for a short while. I went to a meeting in Cape Town and that meeting was on the history of the Khoisan people who speak with clicks in Southern Africa.
There were historians and geneticists, anthropologists, linguists. I said, "What would be the most interesting question, if I could answer one question?" They said, "You should go to Tanzania and study the Hadza and Sundawe," who are either current or until recently were hunter gatherers. They also speak with clicks, like the Southern African San populations. They said, "Try to find out how they are related to each other and to the Southern African populations."
That's what got me started. I went to Tanzania and figured well, if I'm going to study those groups then I'd better study the neighbouring populations because maybe they've interbred and it's going to be important. Well, that turned out to be a really good move.
Once we did that, we could start characterising the extent of diversity. That got me even more intrigued. So I decided let's study other populations throughout sub-Saharan Africa that represent the most linguistically diverse populations, or those that are of interest from an anthropological perspective or maybe have some interesting adaptive traits.
For example, Central African hunter gathers commonly referred to as pygmies, they have a very short stature and that is thought to be an adaptive trait, so I wanted to understand why they are short.
I wanted to understand, why are East African pastoralists tall, and how is it that they can drink milk? Whereas the ancestral state of most humans is that they can't drink milk. So that's an adaptive trait that arose in Europeans. We wanted to know did it also arise in African pastoralists? And indeed it did.
We actually found several novel mutations that arose independently from Europeans. We were able to estimate the age of those mutations and they correspond remarkably well with the archaeological record for the origins of cattle domestication in Africa. In particular, the introduction of cattle south of the Saharan desert, which was after 5,000 years in East Africa. So it's a really cool example of gene culture coevolution.
Kat: When you are gathering these samples, investigating and studying these populations, you've got to be a bit sensitive. I can imagine it doesn't do well to go marching in, in a white coat and say, "Give me your DNA, I'm going to take it away and rummage through it." How do you go about doing this kind of research in a way that is sensitive?
Sarah: The only reason that I am still doing this research after about 19 years is because we were really careful to do it in a sensitive way right from the start. That wasn't the easy way. At the time, there were a lot of people who weren't even getting permits, they weren't getting informed consent from people. They were sort of flying in and flying out. We didn't want to do it that way.
The most important thing is that you have to have local collaborators. So we had people in each country who were trained as geneticists or as anthropologists and they were key partners. There has to be a partnership. They are also going to be the ones that are going to make sure that you're doing this in a culturally sensitive way and an ethical way.
The other thing is, even though it's very time consuming, we have to get permits at every country. That means that we go through extensive ethical review at the level of the government. That's what takes the longest, I would say usually between about three to five years before we ever can start the fieldwork.
Kat: Wow!
Sarah: Just setting up permits, going through ethical review. The longest record was nine years. So, we don't take shortcuts but I'm glad that we didn't because now we're able to continue with this research. And we wanted to have long-term relationships. So we are able to go back to these same communities.
The other things we do are that our team that does fieldwork consists predominantly of Africans. When we are visiting a village, we always talk first to the village chief and we explain what we're doing and why are we doing it, and what are the risks or the benefits or lack of benefits. If they agree, they'll often help us with putting together a community discussion.
We spend a lot of time answering questions and we are often in places for long periods of time. This is not like we hop in one afternoon or morning and we just do this, it takes a long time. So, we want to maintain long-term relationships.
One of the other things that is really important is to actually return results to the participants. As much as possible, we have tried to do that.
I actually just got an email a few days ago from a person from one of the groups that we have studied in Kenya back in 2004 and 2006. We had left our contact information, they wrote and said, "We'd like to get an update." I said, "Sure, this is great!" So that's also important to do.
You have to respect local cultures and beliefs. You can't be coercive, so we don't pay money to people to participate. We might give a small thank you gift, but nothing that would be so much that they feel pressure to do this.
What's reassuring to me is that a lot of people choose not to. So that's actually a good sign that they are not being forced to do that.
Kat: When you are doing this research, engaging with communities, finding things out, how do they respond? What do they want to know and how do they take this kind of interesting work that you are doing
Sarah: It really depends on the population. To me, what's interesting is that in many of the African populations that we've studied, they have a particular interest in history and ancestry.
That's not always the case. Native American populations or Oceanic populations may have concerns about that. We did not find that.
In fact, I did a workshop with an anthropologist in Tsumkwe in Namibia. There are a number of San populations in that area. He organised this working group to explain to the population what the geneticists are doing and why they are doing it and what the results are.
It was great because they had translators and they would translate everything into the local language. There was plenty of time to ask questions and things like that.
At the end, when we asked, "What would you like out of this?", basically they wanted essentially an ancestry test. They wanted a 23andMe result. We explained that that is a problem. We can't give individual results because another concern is paternity issues.
It would be unethical at this point to give back individual information, so we give information at the level of the population.
Kat: I can see that being a problem… One of the other things you mention that is interesting, it's not just about studying origins and diversity and the inter-relationships between populations, it's also about health.
I know that you've raised the issue recently in the scientific literature, about the importance of having more diversity in the databases that we use to develop tests and treatments, particularly as we are moving now into a much more genetically informed area of medicine. Why is that so important?
Sarah: Well, it's important if we want to be more inclusive in human genetics research so that everybody may benefit from the research. I think that if we don't include ethnically diverse populations, it's just going to exacerbate health inequalities.
So we recently did a publisher perspective where we looked at a genome-wide association study database. That's where they are looking at genetic variations and their association with disease risk or sometimes normal variable traits.
We found that about 80 percent of the individuals included in these studies are of European ancestry, about 10 percent East Asian ancestry, about 2 percent African ancestry, 1 percent Hispanic ancestry and less than one percent, everybody else in the world.
Kat: There's a lot of other people in the world!
Sarah: Yes, absolutely! So we're just missing out. We don't know about the diversity that exists. We know that there are differences in the prevalence of certain diseases, and we know that health disparities can be caused largely by socioeconomic factors and diet and behavioural factors.
But in some cases there could also be genetic risk factors and so it's important to understand both the genetic and environmental risk factors for a disease. In order to do that, we have to study diverse populations.
The other issues is that nowadays people are applying in the clinic something called a polygenic risk score or genetic risk score. These are based, so far, on European studies because those are where they have the largest number of individuals, sometimes hundreds of thousands of individuals, and sometimes you need that to get statistical power.
So when they find these associations, they can look -- for example, say you are looking at heart disease and they want to know how many variants do you have that are associated with risk of heart disease? You sort of add them all up and that gives you a genetic risk score.
Now, people have shown that when you do that based on European populations, it just doesn't work in other populations. So we are actually potentially giving the wrong information to people and certainly they are not going to benefit from that.
We have to better understand why these genetic risk scores don't translate. We have to understand if different populations might have different genetic risk factors. Or it could be that they have the same genetic variance but in a different environment, the trait is different or the disease is different.
Kat: It's interesting that we've moved in the past couple of decades from the human genome and the original genome coming from a very small number of people, to what I like to think of as the idea of the global genome. Understanding the human genome with all of its different global variations. Do you think that we'll get there or do you really think that we need to have everybody, the whole world's population - we'll only really understand it when we've got everyone?
Sarah: No, we don't have to have everybody. But we should have at least a decent representation. That could be determined based on -- sometimes it's based on what we know about linguistic variation or the history of populations.
If we're not even looking, we're not going to know what we're missing. So we just have to do a much better job of doing that. That means starting at the level of funding organisations. They have to be able to put resources into this.
There's also a need when doing this sort of research to build capacity locally and train people locally. That's also going to be very important. Ultimately, the goal would be that people are able to collect that data locally and analyse it locally. So there needs to be better resources for conducting the research and doing the training and the capacity building.
Kat: And finally, now you are starting to gather many different gene sequences, you're starting to understand these populations, are you surprised by the amount of diversity in there?
Sarah: Well, I certainly was when I started my research. As a graduate student this was a huge surprise because at the time, everybody was using some African populations that had been collected by Luca Cavalli-Sforza, he was at Stamford at the time.
He worked from two Central African rainforest hunter gatherer populations, often referred to as Pygmies. People were using these as representative Africans. It turns out they are not at all representative of most Africans.
So when I initiated this work as a graduate student at Yale, it was a huge surprise to see how much variation there was amongst African populations because when we looked amongst Europeans, we didn't see that variation or amongst Asian populations. But every African group was so different from each other.
That's what really set me upon this journey. We are always studying new things that amaze me because there's also a lot of functionally important variation that may be geographically restricted or even unique to certain populations.
We're trying to now really zero in on genetic variants that play a role in both normal variable traits like for example skin colour and height. Also disease risk, infectious disease resistance, for example. Then use functional genomics approaches to actually identify what are the actual causal variants. What is the variant that actually is impacting that trait?
Kat: And as well as the information about life and health, understanding our human story about where we came from and where we're going?
Sarah: Exactly, there's still so much more to learn. That's what makes this field so exciting.
Kat: Sarah Tishkoff, from the University of Pennsylvania.
Garrett Hellenthal - Connecting culture and genetics
Kat: Another person I caught up with at the conference Garrett Hellenthal is a statistical geneticist at University College London who has been collaborating with researchers working in Ethiopia, gathering information about the genes and culture of the various groups of people living there to see if there are any correlations between the two.
Garrett: One great thing about Ethiopia is the fact that it has an incredible amount of cultural, genetic and also linguistic and all kinds of different types of diversity, different topographies. So one of the main aims of the study was to see how genetics correlates with all of these different types of factors.
Kat: So to see if maybe different cultural groups, different ethnic groups keep their genetics to themselves or whether they are mixing around?
Garrett: Exactly, and what sort of factors determine whether they mix around? Is it shared geography, shared language, similar languages, that type of thing? What sort of things even act as barriers to groups intermixing?
Kat: So tell me about some of the groups that you've studied? What did you find? Who were you looking at
Garrett: Well, we're still clawing through the results because there's plenty of things to look at. We've already found a few interesting things.
In general, there is a trend where genetic groups are on average, more genetically similar to each other than they are to other generic groups. You do see a lot of this. Some of it falls pretty strongly along linguistic lines.
So you've got what seems to be very ancient relatedness between particular linguistic groups that nonetheless live in the same areas but they're still quite different, genetically.
Kat: So if you don't speak the same language, you're not going to get together?
Garrett: Yes, sometimes. Although also I would say there's been a lot of evidence where that's not true. Where you see these crossing across different language lines as well. Where people from very different language groups seem genetically pretty similar.
Kat: That's languages. What are some of the other groupings that you see?
Garrett: One particularly interesting one, there's a group called the Ari, who amongst other groups in Ethiopia, they are kind of divided into these social hierarchies based on occupation. It turns out in this particular ethnicity, if you work as a cultivator or a farmer, you enjoy a higher social status than those who work as blacksmiths or potters.
There's also occupations including weavers who are also considered to be a bit higher status, so weavers and farmers are a bit higher and then people who work as tanners, potters or blacksmiths are a bit set aside in the social hierarchy.
Kat: Bottom of the ladder.
Garrett: Yes, marginalised a bit, I guess, so there's not much intermingling between them. So, if you work as a cultivator, you may not want to be associated with the other groups or spend time with them, or dine in their homes, that type of thing.
Kat: So when you look at the genetics of these different social groups, what do you find?
Garrett: First of all, kind of shockingly as they are quite genetically different from one another, if you look at individuals that are the same ethnic group but work in these different occupations, of one works as a farmer, another works as a blacksmith, you can see very strong genetic differences between them.
To the extent that the people who work as farmers are actually much more genetically similar on average to other ethnic groups. Which is typically not the case that we see in most other ethnicities. They are more similar to other ethnic groups than they are to other Ari who work in these different occupations.
Kat: So hang on, you're saying that people who work in some occupations in this group are more similar to people who are completely outside the group. So what's gone on in history then? The farmers in this ethnic group, have they come from a different population? What can this tell us about the history?
Garrett: Yes, so these caste-like occupational groups in Ethiopia have been studied for some time by anthropologists. Sort of simplifying things, there are two major theories that anthropologists have proposed to explain the existence of these different groups.
One is that as you say, they are quite anciently related. There's this idea that these blacksmiths and potters descend from these hunter gatherer groups. These would be among the original inhabitants of Ethiopia that have been living in that area for a very long time.
Then when you have the advent of farming in the Neolithic era, you had different farming communities coming into the region. It was believed by this particular theory that farmers today descended from this other, very distantly related group of farmers. So they've been at odds with each other and not really communicating for a very long time.
Another theory however, which was posited by Herbert Lewis in the 1960s, is that actually they are all one group, they are all Ari and so maybe they've got very similar origins, but once one of the groups with the advent of blacksmithing and these other technologies started to take those trades up, over time there just became this kind of isolation between the two groups within the community, due to this occupational choice.
Kat: Right, so after a while the farmers were just like, well, we don't hang out with the blacksmiths, we don't talk to them.
Garrett: Exactly. It was totally a societal construction, it wasn't this ancient relatedness or who are these new people? It was more like we've just decided that yes, we're no longer talking to people that work in this particular profession.
Kat: How are you using genetics to untangle what's actually happened in history? What did you find?
Garrett: Yes, so as I mentioned initially, when you look at these groups they seem very genetically different if you've used the standard techniques. It's kind of crazy, to the extent that if I just have the DNA of somebody, I can predict exactly what their job is in one of these groups. You can easily figure out whether they are a farmer or a potter or a blacksmith.
We did a slightly different analysis where if you take the same individuals, and rather than just blanket comparing their DNA to each other within these groups, you can take each of them and compare them to groups outside of Ethiopia.
What this does is it allows you to look a little bit back further in time. You avoid endogamy, recent intermarriage within the groups. So if you're a potter, you are only intermixing and intermarrying with other potters, which is consistent with this idea that they have been marginalised and nobody else is mixing with them. Then you'll get these kinds of genetic differences over time, quite rapidly, possibly.
So what we did was we tried to get rid of those effects a bit by instead taking our individuals and comparing them to non-Ethiopians and seeing how they are related to non-Ethiopians. Did they relate in the same way? If so, that suggests that maybe actually they do share similar ancestral origins.
Kat: And what did you find?
Garrett: When we did this, kind of miraculously, these differences completely disappeared. So this idea that you had these groups that were completely genetically different - so for example the farmers looked more similar to other ethnic groups than they did to other Ari who work as blacksmiths. We instead found that when you compare them to non-Ethiopians, they are most similar to each other than they are to any other ethnic group within Ethiopia. You completely get rid of these kind of recent isolation effects.
Kat: So that basically supports that second idea that they are basically the same people and then somewhere along the line they have just decided that they are not talking to each other.
Garrett: Exactly, yes. We think that the most likely explanation by far and the one that is most consistent with the data is exactly that, that they share the same recent origins. That kind of makes sense, the same ethnic identity.
It's only recently, once one of them picked up these different occupations, over time, society has put pressure on these different jobs and decided that now they're going to stop intermixing. That has led to genetic differences that we can observe today.
Kat: So they are not interbreeding, not intermingling but… I do want to know, do you see any kind of Romeo and Juliet events? Do you see people that have crossed those social lines for love?
Garrett: Yes, as you'd expect there are always exceptions in these things, so yes. I think in the original collection we had about 10 individuals from each of the farmers and the blacksmiths. In one or two of those individuals there is clear evidence that one of them was about 50:50 each, genetically. So it seems like a first-generation offspring that had a parent from each camp.
Kat: Crossing the social lines!
Garrett: Yes. And another one probably had a grandparent in one of the different groups. So yes, that's 2 out of 20 or so where you see evidence of crossing these lines.
Kat: So these techniques that you've used, where are you trying to look next to untangle these relationships between genetics, culture and diversity?
Garrett: Well, we're still looking at other groups in Ethiopia as well. We've got data from the Ari, there's another group called the Welayta, who also practise this social stratification by occupation.
We're seeing similar things. You're seeing again, some degree of intermixing between the different occupations but you can still genetically tell them apart.
So we are looking at other instances in Ethiopia, but also I'm quite interested in studying other parts of Africa as well. Looking at Nigeria, Cameroon and other places where there's tons of ethnic diversity, tons of linguistic diversity, lots of different topographies, and trying to see what the factors are that are really promoting or inhibiting gene flow between groups.
Kat: It feels like this is another layer on top of all the other work that historians, anthropologists, archaeologists do to really unpick this human story of who we are and how we all came to be here where we are.
Garrett: Yes. We're hoping that genetics can be used as another tool in these types of studies. It's actually quite gratifying with the work on the Ari - we published something on this in 2015 and Herbert Lewis, that I mentioned, he was the one that proposed this idea that there's just this recent isolation between these different occupational groups.
About a year after we published he said he randomly came across our paper and he reached out via email. At first he said, "You didn't quite cite me properly." We were like, "Sorry", which is very fair enough and we felt quite embarrassed about that.
But then he was very gracious and said he was very happy that we've found something that provided additional evidence to his theory that he had been proposing for so long.
van Dorp L, Balding D, Myers S, Pagani L, Tyler-Smith C, Bekele E, et al. (2015) Evidence for a Common Origin of Blacksmiths and Cultivators in the Ethiopian Ari within the Last 4500 Years: Lessons for Clustering-Based Inference. PLoS Genet 11(8): e1005397.
Lucy van Dorp - Unearthing history in the genome
Kat: The Ari people aren’t the only African population whose culture and history is written in their genes. Garrett’s former PhD student, Dr Lucy van Dorp, is a ‘genetic archaeologist’ at UCL who’s comparing DNA from many people, ancient and modern, to figure out when certain gene variations and changes appeared in different populations and piece together a historical story about who was doing what, when and with whom.
This kind of evidence is increasingly being used to support or refute other sources like written records or archaeological sites. And when that kind of stuff isn’t easy to establish or doesn’t exist, this immortal DNA story becomes even more valuable.
Lucy: If we look at the genome, it really contains a legacy of past interactions. That might be interactions of us as a species or any other species we happen to have genomes from. This is because obviously, every time we mix we share our DNA and pass on some of that genome.
This means that if we're able to use statistical methods to figure out which bits of DNA come from different people or from different populations, we can start to make inferences about how people might be more closely related to each other for various historical reasons, but also track the legacy of large scale migration events and population replacement events.
A population replacement event would be a place where you have, for example, a large scale migration, and the existing population is wiped out.
So one of the really exciting things, I think, about DNA is that it is really this unbiased account of interactions. A lot of our understanding of the past is based on the fields of linguistics, history, archaeology and anthropology but if we look at DNA we have something completely independent.
We don't need to rely on a written record. Instead we can just ask questions of the genome. Where do we see interactions through time?
Then in some cases we can link these to known historical events. In others we get this tantalising glimpse into what may have happened in the past without actually having to know very much about history itself.
Kat: One interesting example Lucy’s been researching is the story of the Kuba Kingdom - a sophisticated society that flourished hundreds of years ago in what’s now the Democratic Republic of the Congo in central Africa.
Lucy: This kingdom was formed in about 1625 by an individual who moved to the area and joined a set of different ethnic groups that existed there, into what became known as the Kuba Kingdom and became what we now consider a centralised state.
The exciting thing about this kingdom is that it was really innovative. It was a hub of trade and it had many of the traits that we associate with our own societies today: the concept of a capitol city, trial by jury, a public police force and public goods provision. But all of these things arose independent of any Western input.
So one question is that if we take the DNA of people whose ancestors were part of the Kuba Kingdom or who today define themselves as Kuba, as the kingdom does still exist in some capacity, and compare it to the DNA of neighbouring groups, do we see any genetic legacy of this oral tradition or this historical event?
In particular, can we learn something about how people who were part of the kingdom were interacting back in the 17th Century.
It turns out, if we take the DNA of Kuba people today and we compare it to 26 other ethnic groups sampled within the region, we see something a little bit different. Looking at the Kuba genomes we see that there's much more genetic diversity.
So it really suggests that the Kuba people have a history of mixing extensively. By that I mean that we can identify lots of chunks within their genome that show evidence of migration and movement from other neighbouring populations. This is something we just don't see in what I will call the non-Kuba.
This tells us two things. It tells us that this kingdom wasn't a kingdom of isolation - it was actually encouraging the movement of people. You can think of it as kind of a federal kingdom in that sense, that people were moving, they were mixing. The kingdom was encouraging social mobility and exchange of DNA, of marriage of people.
Also, we can precisely date when we think those events were happening. And we find using just the genome as an independent line of evidence, that this dating fits very nicely with when the kingdom was at its peak in the 17th and 18th Century.
Kat: The Kuba Kingdom was so advanced that European colonisers arriving there couldn’t believe that it was purely the work of Africans. But, as Lucy has discovered, the DNA story reveals that the Kingdom accumulated its intellectual and financial wealth by acting as a kind of metropolitan mixing pot for the surrounding area.
Lucy: Our understanding of the Kuba Kingdom is not that strong. It's well known in the Republic of Congo, but really, in terms of our own documentation, that's been something that has come much more recently through ethnographic and anthropological studies.
Actually, having an independent line of information to resolve some of the questions about the kingdom; did it encourage trade, did it move people, is there a genetic legacy? That's something we can get at with genomes.
One thing I think is quite nice in this example is that we could see evidence of these events in the Kuba genomes, which means that if we were in a situation where we knew nothing about the kingdom, we might question why this group looks so diverse.
This really suggests the possibility that we can start to use genetic information to infer how people have interacted. In this case, the legacy of a socio-political system through time, and even when no written records exist.
I think it's important to couple this with some extra information, for example from archaeology and anthropology, but then we'll be in a position to actually start to infer some of the nature or characteristics of historical events which have left a genetic legacy, looking at the genomes almost in isolation.
Kat: Genetic archaeologist Lucy van Dorp from UCL. And if you want to hear another story about how human culture has shaped our genes, take a listen to the episode in my recent Ingenious series on Radio 4 about the Milkshake gene and the evolution of dairy farming.
Genetic legacy of state centralization in the Kuba Kingdom of the Democratic Republic of the Congo. Lucy van Dorp et al. Proceedings of the National Academy of Sciences Jan 2019, 116 (2) 593-598; DOI: 10.1073/pnas.1811211115
Mutational Meltdown
Kat: And finally, it’s time for a quick look at what’s in the latest episode of the podcast from Heredity, the journal of The Genetics Society. Host James Burgon’s been talking to Professor Michael Lynch from Arizona State University about a potential way to combat COVID-19 - by forcing the coronavirus behind the pandemic, SARS-CoV-2, into extinction through a process called mutational meltdown. Apologies for the slight technical issues in this clip - as with everything right now, blame it on COVID.
Michael: These RNA viruses have very high mutation rates. There’s already been dozens, I guess hundreds of these bugs already sequenced, so this is a situation where you’re seeing evolution in action on a timescale of only a few months.
That’s one of the reasons I think it’s useful to put the whole process in a population genetics context. And a mutational meltdown is one aspect of population genetics that I think has real practical applications, even though in this case we’re talking about driving something to extinction, whereas the concept was originally developed as a guide to minimising the risk of extinction.
James: I think this is the first time on the podcast we’ve ever talked about trying to drive something extinct!
Kat: You can find the full interview in the latest Heredity podcast - just search for Heredity in your favourite podcast app, or follow the link here.
Considering mutational meltdown as a potential SARS-CoV-2 treatment strategy. Jensen & Lynch, Heredity 2020
That’s all for now. Next time we’ll be exploring some more stories from the history of genetics. In the meantime, you can find us on Twitter @geneticsunzip and please do take a moment to rate and review us on Apple podcasts - it really makes a difference and helps more people discover the show.
Genetics Unzipped is presented by me, Kat Arney, and produced by First Create the Media for The Genetics Society - one of the oldest learned societies in the world dedicated to supporting and promoting the research, teaching and application of genetics.
You can find out more and apply to join at genetics.org.uk Our theme music was composed by Dan Pollard, and the logo was designed by James Mayall, transcription is by Viv Andrews and production was by Hannah Varrall. Thanks for listening, and until next time, goodbye.
