Marcus Alexander Talks About the Microbiome Biology and Social Networks



welcome to the Macmillan report I'm Marilyn Wilkes your host and our guest is Marcus Alexander he works as a scientist in the human nature lab at the Yale Institute for Network science his research focuses on genomics of social networks the evolution of human cooperation and large-scale field interventions that improve and extend human life today we'll talk with dr. Alexander about the biome biology and social networks in the developing world project welcome dr. Alexander I'm excited to be here let's start with an overview of the project you're working on tell us about it well for the past two years or so the human nature lab has been running a large public health intervention in Honduras we're running a network targeting trial to improve infant and maternal health and as a part of that this project which is led by Professor Nicholas Christakis he has consisted of mapping face-to-face social networks in a large sample of about 30,000 people across 176 villages Wow and our goal in that project is to deliver health education so to improve health outcomes now the microbiome project really started when I moved here from Stanford where I did my postdoc mostly in genomics I brought to this project my interest in biology my interest in genomics and professor Christakis had a large social network mapped with that bond with a lot of information on it and opportunities to study how health spreads through a human network so this project which I can't take all credit for I have to say that it's really a brainchild of Nicholas Christakis I started by trying to understand what is the distribution of bacteria that colonize human bodies across a network of social interactions okay let's let's talk about some terms use social networks what do you mean by that and also genomics can you define that term as well for us sure so we think social networks to be actual real social interaction so I'm not talking about Facebook we're talking here about villages in a remote part of the world people live there on at most one or two dollars a day they're very isolated and what we've done is we went into the field and we use we developed an app called trellis which is a map for photographic mapping of social networks so we went into this villages and when I say we I mean there's a team of about hundred people working in the field and we map social networks by first taking pictures of everybody so there's a huge basically Facebook so to speak of this part of the world and then we went to people and asked them what we call name generator' question so I may ask you for example who do you go to to discuss important matters with okay and you will give me a number of names I will I will type in the names and we'll you will point to the picture of the person okay so with a number of these name generators we were able to construct what is now the largest map social network ever done by any research group okay so that's what we mean by social network what we mean by the genomic you ask well genome is basically the bag of genes then each of us carries with us that give us instructions on our body instructions on how to function so when we say human genome we really mean studying the genetic code of the entire population okay and why Honduras Welkin Duras as I said is a very remote and a poor area of the world one of the goals of the human nature lab at Yale has been not only to understand how humans interact but also to use the knowledge that we uncover to design better health interventions that can actually change people's lives so the core project in Honduras is really trying to make the delivery of health education to women who may be pregnant or may become pregnant in a very efficient way by targeting key people in the network and therefore helping the intervention spread exponentially through the entire region okay and how long has this study been going on so the microbiome project is a that's a very kind of exciting new work this whole study has been funded by the Bill and Melinda Gates Foundation and by the International Development Bank the new study funded by the normies Foundation consists of setting up an entire set of procedures to collect biological specimens from these subjects okay so this project has started about a year ago and what we've done we've set up a cold chain of procedures and equipment that is required to pick up a sample for example a stool sample in a remote village in Honduras freeze it in liquid nitrogen transported to our local office then prepare it for shipping bringing to the Yale lab and a yellow lab we'll share it with our collaborators Elana Brita is a microbiologist at Cornell she's one of our main collaborators so what we then shared this biological samples and analyzed the DNA that's contained in it okay and what are you hoping to find well we have some hints already that microbiome in the developing world is very different than the microbiome in that we carry here and why is that for example we are exposed to different pathogens but more importantly we have different hygiene practices we are exposed to new antibiotics so there's some hints that the microbiome of this developing area will be much more diverse they will have many more genes that are specialized to do different things adopted to the people who live there for example diet is one of them and one exciting part about that is that as our societies develop and become more industrialized a lot of biological diversity that exists in this bacterial population may be lost so a number of genes a number of species may disappear from the face of earth doing studies like this in the developing world enable us to get a better glimpse at the full genetic diversity and needless to say if we understand the bacteria that people carry we will understand more about the diseases that they are exposed to and how these diseases may spread from person to person let's talk a little bit more about that in terms of some of the things that were talked about in the study terms of obesity for instance and diabetes things that typically you cannot catch from another person but what you're saying is through these things in our bodies that that is possible well expound on that a little bit more yeah sure it's a quite a controversial statement yes it is it was but it was Nicholas's work the work of the human nature lab maybe not 10 years ago that first established in a network of people in framing in the city of Framingham that obesity clusters in a social network that if my friend's friend gains a few pounds I become more likely to gain a few pounds so so far what we think what we've thought of is this process being a social process we affect how each of us behaves we affect each other's norms but what our microbiome study asks is whether there could be also biological mechanism behind it right and that's fascinating exactly one of the big discoveries that was made at MIT Neri calms lab and Ilana Brito has professor bitter has worked on this is this concept of mobile genes so it turns out that human body has about 20,000 protein coding genes bacteria have million millions and not only that but their genes can jump from a strain to strain so there are these little mobile genes that can actually move quite fast through the bacterial population there may be antibiotic resistance genes but they also could be genes that increased risk of diabetes for some people or risk of autism or risk of obesity and other metabolic disorders so this is really an uncharted territory we really feel a little bit like explorers going into a unknown land so to speak of microbiome and trying to map these new bacterial strains and their genes so what would have to happen and order for some research to actually indicate that one can get diabetes from another person I think we're definitely not there yet but the first step I would say is to understand what species and what genes exist in this population okay to give you a very kind of example connected to diabetes carbohydrates are very important in how we process them well it turns out that in different parts of the world people get their hyper carbohydrates from very different sources right so to TIA chips may be the main source of carbohydrates in Honduras Arian Honduras wheat and bread may be here well it turns out that bacteria have evolved genes and have populated our gut our human gut in a way to adapt to processing those particular carbohydrates so anything that may go wrong in that symbiotic relationship between the bacteria and how our body works has the potential to affect a risk of diabetes and other diseases right so ultimately how long will this new study go on for we're hoping that this will be a multi-year study one of the things that we also hope to do is remap all the social networks again and see how they change and where there are change in social relationship is reflected in a change in the type of bacteria or genes that we carry in our gut okay and you know why is it so important that this is studied so I mentioned the idea of biodiversity we really understand very little about the role bacteria play in health recent evidence you mentioned on the diabetes but there is also recent evidence that a number of mental health disorders for example depression ADHD autism anxiety may be linked to the way our gut interacts with the microbiome so as I said it's a very unexplored area when we got when we take this to the setting of the developing world there's an added imperative to actually do something and help people in the region so one of the great pleasures of working the human nature lab has been our ability to directly affect the lives of the people in the field so for example the way we collect these specimens is we have planned to have little village clinics set up in these remote villages where villagers can come and can get screened for through a basic physical and give their samples we give them back a results of some of their studies and we provide free deworming medication for example for those affected so we think that there's a symbiote there's this partnership that we can have between subjects that contributes to our knowledge of basic science and on our part as contributing to their everyday health sure all right well this is fascinating and I'm sure it'll be very interesting to see what comes out of this study so thank you very much for being here with us today and sharing some of your work thank you very much for more information about dr. Alexander and his research please visit our website at macmillan report yale.edu be sure to join us again for another episode of the Macmillan report made possible through funding from the Whitney and Betty Macmillan Center for International and area studies at Yale you

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