Water Challenges Across the Globe

Penn State undergrad Thomas Sontag interviews associate professor Asher Rosinger about his research, which explores how people in different parts of the world meet their water needs.

Thomas Sontag
Undergraduate student at Penn State double majoring in Microbiology and German

Asher Rosinger
Associate Professor of Biobehavioral Health at Penn State

Transcript

Mark Shriver:

From the Center for human Evolution and Diversity at Penn State, this is Tracking Traits

 [THEME MUSIC]

 Cole Hons:

Greetings fellow homo sapiens, this is Cole Hons from The Huck Institutes of the Life Sciences. Welcome back to the podcast. 

For Episode 3 of this third season, we bring you Penn State Biology undergrad Thomas Sontag interviewing Asher Rosinger, associate professor of Biobehavioral Health at Penn State.

Dr. Rosinger directs the Water Health and Nutrition Lab and is an active member of the Penn State Water Initiative. His overall research program is designed to understand how humans meet their water needs, how this relates to adaptation, environmental changes, and water insecurity, and the resulting health, hydration, and disease consequences.

In this podcast conversation with Tom, Rosinger discusses his interest in understanding how humans meet their water needs and the health outcomes associated with different strategies. He explores the diverse challenges of water insecurity, and shares his experiences working with different populations in the Bolivian Amazon, Northern Kenya, and the United States, studying the impacts of water on health and human biology. 

He also discusses the link between extreme climatic events and health outcomes, particularly in relation to water needs and adaptation. Rosinger emphasizes the importance of addressing water insecurity as a humanitarian issue and ensuring access to clean water for all.

Here's Thomas Sontag interviewing Asher Rosinger about “Water Challenges Across the Globe”

 [MUSICAL INTERLUDE]

Tom:

Many thanks for taking the time to come here today. It’s hard to think of a topic that’s more vital than the human need for water, so I think this chat is going to be very interesting. As a starting point, can you give us a rundown of your research? 

Asher:

Yeah, thanks for having me, Tom. It’s fun to be part of the Tracking Traits podcast. First time on the show. My research really spans quite a few different numbers, but all of them are wet, being that I’m really interested in how humans meet their water needs, especially in areas without access to clean water. The way I conceptualize and think about water is  really holistic. So, you or our listeners might be thinking about water, just what comes out of the tap. But water is in foods as well. Water is in the environment. And so I'm really interested in understanding all the different strategies that humans across the world use to meet their water needs. And then what are the different health outcomes that are associated with variation in the strategies that people use to meet their water needs? I am particularly interested in water insecurity or the experiences that people deal with in navigating water challenges, water problems. And those water challenges are quite diverse as well. When we think about water insecurity in particular, a lot of people just think of water insecurity as water scarcity, people not having enough water, but in fact, water insecurity can occur when there's too much dirty water as well. Or if you have aging infrastructure, you have pipes that are leaching lead into water sources.

So I try to navigate all these different areas. I work in the Bolivian Amazon with forager-horticulturalists in Bolivia. I also work in Northern Kenya with semi-nomadic pastoralist population, the Daasanach. And in that context, they don't have enough water. And then I also work in the United States where we've been dealing with water infrastructure problems and trying to understand how tap water avoidance is increasing in the United States. And then what are the impacts on different beverage strategies consuming sugar-sweetened beverages. One of the interesting emerging topics that I've increasingly become interested in, I just guest-edited a special issue of American Journal of Human Biology for the January issue of 2023, was trying to understand and link extreme climatic events to health and human biology outcomes. Because right now with global climate change, we're seeing an increased frequency of extreme climatic events; flooding, droughts, extreme storms, hurricanes, cyclones, and all of those have huge implications for health and human biology.

How humans are able to adapt to hotter temperatures. What does that do to our thirst perception? What does that do to our kidney health? What does that do to the different strategies that people use to meet their water needs? And how are they able to adapt to these stressors that are in their lives, which humans have navigated over the last few million years, but now we're really starting to see an increased frequency of? And one of the things that I've been very interested in, especially recently, is in Northern Kenya, the population that I work with, they live in and around the banks of Lake Turkana. Now, in the context of human evolution, this is really interesting. This site, because this is the site in which we have the oldest human footprints, so they're more than 1.6 million years old of Homo erectus. And we have some of the earliest Homo erectus fossils.

So this is this bedrock of human civilization. But there are people that live there still today, right? The Daasanach pastoralists have been living there for thousands of years, and the lake that they live in and around is a moderately saline alkaline lake. One of the things that we've been interested in and that I've been investigating is how is the salinity of their drinking water affecting their health? How is it affecting their kidney function? How is it affecting their blood pressure and hypertension? Because we know that non-communicable diseases, chronic diseases, are the leading causes of mortality worldwide. And so we're really trying to understand the impacts of climate change on changing water tables, increased salinization of water sources. What are the impacts on health and human biology in that context? And so quite broadly, I'm interested in all of these different topics related to water, health and human biology.

Tom:

Huh! When I think about water insecurity, I don't usually think about how some people might have to deal with slightly salty water. Are humans like any other mammal or is there anything special about how much water we drink?

Asher:

When we think about humans and the different physiological adaptations that we have developed over our history, you can look at a few different key things. So, first of all we have a lot of physiological adaptations as well as some genetic adaptations that allow us to conserve body water. And those things are things like the external nose – the “schnoz” ­– you're able to retrieve moisture from your exhaled air that helps you conserve body water. We also have our kidneys, which are really important in terms of conserving, concentrating our urine to be able to conserve our body water. Those are crucial. We also sweat, which is quite novel, and especially we have the most amount of eccrine sweat glands, which allows us to cool ourselves off in extreme heat. That allows us this ability to be able to go out into the heat, moderate and buffer heat stress as we are exploring the environment. All of these different adaptations are crucial to be able to kind of navigate our water needs.

Now, when we think about our dependence on water that's just out there, humans are quite dependent. We really can only go about three days, three, four or five days without any water before we risk dying. And so some, we're not like camels. We can't go weeks and weeks and just load up on a lot of water and survive. We have to be able to have a water source that's relatively nearby. Now, one of the cool things that humans have adapted to, and we're able to is we've slightly decoupled our thirst perception from our hydration status in such a way that we can lose about 1 to 2, 3% of our body weight in water while we're going out in the environment, potentially hunting, gathering, doing tasks, exercising without it really affecting our cognitive capacity and our physiological capacity.

You do start to see some cognitive deficits when you get beyond 2 to 3% dehydration, but it's not deadly. And so that allows us to have a competitive advantage, and then we need to get back within about a day or so to get back to a water source and rehydrate. And then it takes about 24 hours to rehydrate if you're moderately dehydrated.

Tom:

And what are some of the methods people have used in the past to survive where there are few sources of clean water?

Asher:

There's a lot of different strategies that humans have used to meet their water needs. When we think about the history of human civilizations, we can look back at a lot of different regions and where they've aggregated. Oftentimes they're around areas that have water, so around rivers, around lakes, fresh bodies of water. And what's important there is that those amounts of water are critical for increasing the caring capacity in those regions. Now humans are really smart, and one of the things that we have been doing over the last 2, 3, 4,000 years, you can look all the way back to Petra in Jordan. You can look at Caesarea in Israel. You can look at these hubs in which humans have modified their environment and used a series of natural catchment basins and have transported water to areas where people are living to be able to support an increased population.

So in Caesarea, in Israel, this is a town on the Mediterranean Sea that the Romans colonize when it was, now it's present day Israel, and they were able to transport through the Roman aqueducts, water from the Jordan River, which was 17 kilometers away. And that allowed people to have a city that carried way more people than was, would've been possible without those water systems present. Now, if you kind of move forward in time, and we think about what are the ways in which people have dealt with once population sizes started to increase, well, what do people do? We shit. (laughs) When you have a lot of people, you get contamination of water because what breathes has to also excrete, right? And so when we're consuming food, we have to go to the bathroom. Where does that waste go if you don't have proper sanitation? That can oftentimes end up in water supplies.

So one of the coolest nutritional adaptations that is one of my favorites are beers, small beers and fermentation. The fermentation process is actually quite amazing because fermentation lyzes bacteria. It kills off bacteria. So the population that I work with in lowland Bolivia, the Chimane, they have this cultural custom that's quite similar to many other groups in the Amazon and in South America, which is the consumption of chicha. Chicha is a homemade traditional beverage that's made out of yuca, manioc.

And women will chop it up and then boil it, and then they chew it up, they masticate it, and they spit it out into a big bucket, and their saliva interacts with the water and with the yuca, and it actually creates the fermentation process. They set it aside, and after a couple of days, it becomes mildly alcoholic. And so if you're living in an environment where the water is not clean, where it has bacteria or parasites in the water, that fermentation process actually serves to clean the water. And this is similar in terms of many other techniques of making beer. So small beers in the Middle Ages were a big hydration source. People didn't drink water because it was contaminated. And we see this as this nutritional adaptation to dealing with water quality issues.

Tom:

You mentioned how people in the Amazon might use yuca to produce alcoholic beverages. It just amazes me that they found so many uses to yuca, because I'm Brazilian and I've been to the Amazon, and it is just incredible that they figured out a way of using yuca despite it being extremely poisonous when grown in those soils. And they just have to let it sit for several days in water, and in this case with spit before they can use it. It's just amazing how resourceful people can be when dealing with water and other basic needs.

Asher:

Yeah, so there's actually a couple different varietals of yuca. Some of them in Brazil in particular, those are the ones that are more toxic. The yuca species in lowland Bolivia actually is not as toxic, so they don't have to do that custom that you're describing in the same way. But you're right, the nutritional adaptations for the poisonous yuca is even more extreme what you're describing. But that goes to show how important these food resources are, both for calories, but also for water. And food is a huge water source. And in lowland Bolivia where I was, I've been doing work since 2009 with the Chimane, one of the first things that I was really exploring there was, okay, this is an environment with too much dirty water, so how are they going to meet their water needs? So I started asking them, and I never saw people really drinking much water, but I did see them eating papayas.

I did see them sucking on grapefruits. So I started thinking, well, huh, I wonder how much water they're actually getting from all of those fruits. So I ended up measuring it, and what we found was that Chimane were getting more than half of their water from food sources. So they were getting way more water than we consume in the United States. They were getting about 4.6 liters of water a day. Whereas in the US we get three and a half liters of water a day or three liters of water a day. And not only were they getting plenty of water from this ­– from these food sources and other liquids, but as they got more of their water from food sources, their probability of diarrhea went down. So their hydration strategy was actually protective against unclean water and their risk of getting diarrhea.

Tom:

I know you've also been to your other places, but which field trip do you feel like was the most interesting?

Asher:

Well, I've been doing research in Bolivia since 2009. I've spent, I don't know, probably two to three years in Bolivia in total. I've done several field trips to Northern Kenya where I've been doing research. I would say probably just because it was in my first, my field work in Bolivia was one of the most memorable. I'll tell you one story related to water in which you're doing research in the Amazon, you're sweating. We were boiling all of our water.

Tom:

Oh, yeah.

Asher:

Drinking boiled water, that's like from a pot, it's not…it's hard to drink. We tell people, we make those recommendations, “You need to boil your water.” But it doesn't taste good and so it makes you not want to drink that water. So you're kind of dehydrated. It's an incredibly taxing environment. You're in the Amazon, you're wearing long sleeves because of all the mosquitoes, so you don't get as many mosquito bites.

So I had noticed on my own that papayas are delicious, right? And they also are water rich, but I didn't know how water rich they were. So one night after being out in different households doing data collection, asking people about where they're getting their water from and everything, I came back and after dinner, I was still kind of hungry and really thirsty. And so we had a bunch of papayas. And so I opened up a papaya and I ate it. You can just eat it with a spoon. And it's so amazing in the Amazon, it's like no papaya that you've tasted in the United States. The soil [inaudible 00:16:13] everything, it's so water rich. So I ate, I just devoured this pretty big papaya. And then because it's so hot and humid, when you get into your mosquito net at night, you strip down basically all the way down to just your underwear, and it gets up to a 100% humidity every night.

So if you don't do something about your clothes, when you wake up in the morning, your clothes are soaked. So what I would do is I would roll up all of my clothes, put it into a Ziploc bag, and then that way in the morning I would take them out and they wouldn't be wet. But it's a big pain in the A, right? So I did that. I'm laying in my mosquito net about 9:00 PM, 10:00 PM, praying for a gust of wind to come and cool me off. And all of a sudden the urge to pee hits me. And I'm like, "oh, no, I'm going to have to put on all my clothes." So I do that. I get up, I go pee, I get back in. About an hour later, I need to pee again.

And I'm like, "oh my gosh." And that happened three times that night. So I started thinking, I'm like, "Why do I have to pee so much? Because of the papaya." And I went back and looked it up, and one large papaya has more than two thirds of a liter of water in it. And so consuming that right before bedtime was a mistake that I did not repeat.

[MUSICAL INTETRLUDE]

Tom:

Shifting gears a little bit, I feel like more and more people avoid drinking tap water, instead opting for bottled water. How do you feel about that?

Asher:

Sure. Tap water avoidance when people have access to plumbing in their households has been an increasing problem in the United States as well as many other places that are dealing with water quality issues. In the US, we can think about tap water avoidance as related to distrust of a person's water source. Now, I've done a lot of research on this in the US looking at trends over time. So is this becoming more common? Is it becoming less common? And for which groups? What we've found is that for marginalized and minoritized communities, so black and brown communities in the United States, they're significantly more likely to avoid drinking their tap water. And this has become more common since the Flint, Michigan water crisis. So if you're not aware, in 2014 into 2015, the city of Flint, Michigan had a lead contamination crisis in which they switched their water source the Detroit River to the Flint River.

And because of the corrosive elements in that water, it then leached lead into people's water, and it increased the lead concentration in people's blood and was really bad. It affected kids negatively. Now, that community was predominantly black, and this got a lot of media attention. It was national news, and national news was actually quite late to covering this. But once they did, it made headlines everywhere. And there's still, the city of Flint, Michigan is still dealing with this, but it's more likely that black and brown communities in the United States suffer from poor-quality water. Now, those historical forces increase distrust of tap water throughout the US. So if you are part of a community that's been discriminated against or that has been dealing with water quality issues, it's completely rational to not drink your tap water and instead shift what you're consuming to something like bottled water.

Now, in most places, water quality in the United States is really good. The EPA is able to regulate it through the Safe Drinking Water Act, whereas bottled water is regulated by the FDA. And oftentimes, many studies have shown that the water quality in bottled water is either tap water that's just been bottled somewhere, and sometimes it actually does not have enough fluoride and has more bacteria than tap water. So it's actually and oftentimes worse quality. Now, the EPA just finally announced that they're going to create water quality standards for forever chemicals like PFAS and PFOS, which is great. It's an expansion of their ability to ensure clean water, which is something that a lot of people, even in wealthy communities like Wilmington, North Carolina, have been dealing with. And so how I feel about tap water avoidance and bottled water consumption is that bottled water is so expensive. It's so expensive!

 Americans spend 40 to 50 billion dollars a year on bottled water, whereas overall, all of our water bills in one year are around 70 billion. So if we were able to take the money that people are using to spend on bottled water to drink and invested that in our tap water and municipal water systems, we would be able to fix all the pipes and do everything so that people could use their tap water. Now, on top of that, we have to make sure that people trust their tap water, right? So we need a social science component to go along with just replacing taps. Because if you're in a community that's been marginalized and have been lied to about your water quality, then it takes a lot of effort to start trusting a water source again, like a tap.

And the last kind of point about that that I want to say is that when people don't trust their tap water and they avoid it, they oftentimes switch to less healthy sources like sugar sweetened beverages. And sodas, which are sugar sweetened beverage, are really bad for our health. They lead to higher risk of weight gain, cardiometabolic disease and diabetes, and all cause mortality. So it's really important that we create an environment, we have to deal with the structural problems of tap water avoidance, of unclean water sources, of distrust to ensure that people trust their water and they have access to clean water so they don't drink sugar sweetened beverages as an alternative to water.

Tom:

Okay, I'm sure you've heard this question a bunch of times, but since you're an expert on the field, I have to ask. Can you tell us how much water we should be drinking daily? Is it okay for us to just drink water whenever we feel thirsty?

Asher:

Sure. So, I love this question because I get it all the time. When we think about human water needs, the most important thing that we have to remember is that there is no one-size-fits-all recommendation for water. The National Academy of Medicine, the Institute of Medicine, they put out recommendations for water in the United States. There's also European recommendations. Since we're in the US I'll give you those recommendations. Now, this is the adequate intake, which means that it should meet the majority of people's water needs in moderate temperatures for moderate physical activity. However, before I give you these numbers, what I want to emphasize is that when you are in heat, when you're in hotter temperatures, when you are exercising, if you are bigger, your water needs will increase. And so thinking about water needs is like, “this is how much I need to drink every single day.” That's just not accurate, because you need to understand that your water needs will shift somewhat from day to day.

So for men, on average in the United States, they say to drink about 3.7 liters of water a day. For women, because women on average are smaller, their water recommendations are 2.7 liters per day. If you are pregnant, they recommend increasing your water intake to about 3 liters per day. And then if you're lactating, that is a huge water need. And so lactating women should consume about 3.8 liters of water per day. Now you're probably thinking, holy moly, 3.7 liters of water a day, like how am I supposed to drink that much? Well, you don't have to drink all of it from water. As I was telling you earlier, you can get that from your food. The water in your food counts towards that amount of water that you're consuming. So if you eat a lot of fruits, if you eat a lot of rice, if you eat a lot of soup, that is a lot of water that you're consuming. You then do not need to also consume an additional 3.7 liters on top of that. All of that water from fruits and foods, that counts.

Tom:

And I know it's possible to suffer from low concentrations of electrolytes after drinking too much water. Is that a risk people should keep in mind, or can we err on the side of excess and drink a bit more water than we need to make sure we stay well-hydrated?

Asher:

So for the typical person who's not running a marathon, if you drink a little bit more water than what your body needs, your body has an amazing way of dealing with it. You just pee it out! Your kidneys will just dilute and you excrete that water out, so you'll be completely fine. Now, what happens in races where a person is running in half-marathons, these extreme races, if a person drinks too much water and their electrolyte balance gets skewed, then a person can suffer from hyponatremia, which is this electrolyte imbalance. And that is the most deadly form of electrolyte imbalance in races. So more people during marathons actually die from hyponatremia than dehydration or hypernatremia. So for those runners, you know drinking Gatorade, drinking electrolyte replenishment beverages is more important. But for a typical person who's listening to this who's not doing an ultra-marathon, you know if you drink a couple extra cups of tea or water, you're going to be fine. And you know what, we sit too much. So get up and go to the bathroom and pee. (laughs)

Tom:

All right. Asher, do you have any advice for students who will soon be joining the world of research?

Asher:

Yeah, one of the things I always tell my students is, early in your career when you're a student in college, reach out to a professor that you're interested in the type of research that they're doing and see if you can join their lab. Every year, I have about eight undergraduate research assistants in my water health and nutrition lab here at Penn State, and I recruit them when they're sophomores or the beginning of their junior year so that they can be in my lab for a couple of years. Getting research experience early on is really important, and the way that I try to train my students is by first introducing them to the subject matter. So I have them do literature reviews so that they're starting to gain a subject matter base. Then I have them work on data entry, data analysis, some of those additional steps.

And as they've started to develop a subject matter base and additional skills in the lab, sometimes we do wet lab work, so running samples for hydration status, urine or blood samples. Then I start to get them to ask questions. Once they understand what's been studied in the past, they can start to think about, “Well, where are the gaps in the literature?” And that's where I try to encourage them to think about additional questions that we can include in the surveys that we do in Kenya and in Bolivia. And then during their senior year, they can then analyze some of those data and write them up for undergraduate thesis.

Tom:

Great advice. What are some of the frustrations that come with your field of research?

Asher:

So I don't think there's a ton of frustrations in human biology. I would say that, you know one of the things that we always have to be doing is making sure that we have enough funding to have our studies going on. And so that's just a lot of work, right? Writing grants. It can be an enjoyable process, and you just have to be resilient and persistent and understand that you need to write, you know five grants to get one, potentially. So, understanding that failure and not getting grants is part of the process, and to not get discouraged about that.

And I think early on when you're a graduate student in particular, it's really easy to get discouraged when you don't get a grant to feel that that's like a personal failure or that your science isn't good or people don't value it, when in fact it's just part of the process. And that there's just so many really interesting, important studies that whichever foundation, federal or private, that's funding the grants, they're trying to evaluate and decide, “Okay, in this cycle, which one can we fund?” And so being persistent and being able to deal with that is a really important skill.

Tom:

And which of your accomplishments brings you the most pride?

Asher:

The two things that I would say that kind of stick out in my mind is when I finished my PhD, as I was finishing up, I applied to the Epidemic Intelligence Service Fellowship with the Centers for Disease Control. And I was selected as one of two anthropologists in this class of 80. And the majority of the fellowship recipients who are disease detectives are medical doctors post-residency.

So being an anthropologist in this really elite CDC force was just an amazing training experience and it really built a lot of confidence in me. I gained a ton of skills that I would not have had otherwise. And having gone through that two-year fellowship, that was a huge accomplishment that I still look back on so favorably. And then second, you know just this past year, I was awarded the Michael A. Little Early Career Award from the Human Biology Association, which celebrated my achievements and research to date and my promise of future research. And that was a huge honor. You know, it really made me feel quite valued that the research that I'd been doing, they viewed it as novel and interesting and really important. And so that's the second accomplishment that you know, has meant a lot to me.

Tom:

When thinking about the humanitarian aspect of accessibility to clean water, what do you think is the issue that must be addressed with the greatest urgency?

Asher:

Right now, about two billion people lack access to clean water around the world. Two billion. That is a gigantic number. It's not fair who does and who doesn't have access to clean water. It's by no fault of the people that don't have access to clean water. This is a structural issue. The biggest issue we need to address is ensuring clean drinking water access to every human on this planet. That needs to be a governmental, intergovernmental initiative to ensure that we meet the sustainable development goal, SDG 6 for everybody, because the United Nations has declared access to clean water as a basic human right. What we need to do is make sure that when we're investing billions of dollars in different areas, we need to invest in getting people clean water, digging more wells, making sure that water that people get is clean, that it's reaching people's homes, that it's accessible and that it's of proper quality.

Tom:

And how did you end up studying water?

Asher:

Well, I've always really been interested in water. I grew up in Israel where there's quite a bit of water scarcity, and I lived in this small town in which we had access to water, but the surrounding Palestinian Arab villages did not. And so from an early age, I was kind of aware of these inequalities between people. And I always kind of thought like this doesn't seem fair. But I was really young when I was living there and didn't really understand that. And then when I got to college, I went to UNC, Chapel Hill, University of North Carolina, Chapel Hill. And I took an anthropology class by accident. I actually, my second semester I was registering for classes and I was really meticulous, and I was like, okay, I'm going to make the best schedule and everything.

I was a psychology major at the time, but I stayed up until 3:00 AM getting it all done. And we had this terrible registration system where you had to log on and then get all your classes and try to register. But as a freshman, I was the last to do that. So I overslept because I accidentally set my alarm for PM instead of AM. I woke up at noon. All of the classes I wanted were taken except for an introduction to anthropology class. So I signed up for that, and I fell in love. It was so amazing because growing up in Israel and the United States, I was already aware, I spoke two languages, Hebrew and English. Similar to you, you speak a couple of languages, and you understand when you speak two languages, that you have different worldviews, different ways of thinking about the world, different ways of solving problems.

Tom:

Absolutely.

Asher:

And it's so real. And it like all of a sudden, anthropology like, made everything concrete to me and made me understand why I was noticing these differences between Israel and the United States in a way that no other discipline really had done for me. So I got really interested in it, and I joined a psychology lab, and I started doing research in anthropology as well. And I was always interested in water, so I started thinking about it more and more and did an independent literature review to try to understand how humans are affecting the environment, because I was taking all these classes on climate change and global health, and I wanted to understand how humans are affecting the environment and affecting water quality and how that then affected people's health. So, you know as I was doing all of this, I realized I needed to go on to graduate school to be able to study this properly. And at that point I figured, “Yeah, I do want to take, get a PhD and go on.” So that's kind of how I got involved, both in water and in science.

Tom:

Can you tell us a bit about the Water Initiative here at Penn State?

Asher:

Sure. So the Water Initiative here at Penn State is a relatively new initiative. Over the last few years, we have a huge number of researchers at Penn State who do water-related research. We have about 140, so it's quite a large number of faculty. So I'm involved in the water initiative in terms of this interdisciplinary approach, because water is inherently interdisciplinary. There's no one theoretical perspective that we use to study water. People can approach it and solve water problems from hydrological elements, from social science elements, from public health elements. So, there's so many different areas of expertise that the Water Initiative is bringing together. I am involved in the water and health part of the Water Initiative. So we are really interested in understanding how water is critical to public health - global public health. And we are bringing together a number of researchers at Penn State to try to tackle this more systematically.

Tom:

I'm glad we had this talk. Thanks a lot for telling us about some less known facts as to why humans need water so much and how we've gotten it in the past. Also, thanks for shedding light on what it's like to be an anthropologist.

Asher:

Thanks for having me, Tom. I enjoyed this and I hope that everybody will have enjoyed this conversation over a cup of coffee or a cup of tea and not get too thirsty.