Posters, presentations, and formalwear: despite the challenge of a virtual environment, this year’s annual Fortin Foundation Bass Connections Showcase still represented the same exciting scholarship and collegiality as it has in years past.
While individuals could no longer walk around to see each of this year’s 70+ teams present in person, they were instead able to navigate a virtual hall with “floors” designated for certain teams. With labels on each virtual table, it almost mimicked the freedom of leisurely strolls down a hall lined with posters, stopping at what catches your eye. Three sessions were held over Thursday, April 15 and Friday, April 16.
The beginning of each session featured five-minute “lightning” presentations by a diverse set of teams, representing the range of research that students and faculty participated in. One such presentation was lead by Juhi Dattani ’22 (NCSU) and Annie Roberts ’21, who covered research generated by their team, “Regenerative Grazing to Mitigate Climate Change.” The team was an inter-institutional project bringing together UNC, NCCU, NCSU, and Duke. And as they aptly summarized, “It’s not the cow, but how.” Cows can help fight instead of contribute to the climate crisis, through utilizing regenerative grazing – which is an indigenous practice that has been around for hundreds of years – to improve soil health and boost plant growth.
One of the most remarkable parts of Bass Connections is how it opens doors for students to pursue avenues and opportunities that they may have never been exposed to otherwise. Hurewitz said that “Being a part of this team led me and a team member to apply for the 2021 Bass Connections Student Research Award, which we were ultimately awarded to study the barriers and facilitators to early childhood diagnosis of Autism Spectrum Disorder (ASD) among Black and Latinx children in North Carolina.” In addition to the award, Hurewitz and fellow team member Ainsley Buck were able to present their team’s research at the APA Region IV Annual Meeting.
From gene therapy for Alzheimer’s disease to power grids on the African continent, this year’s teams represented a wide range of research and collaboration. Erica Langan ’22, a member of the team “REGAIN: Roadmap for Evaluating Goals in Advanced Illness Navigation”, said that “For me, Bass Connections has been an extraordinary way to dive into interdisciplinary research. It’s an environment where I can bring my existing skills and knowledge to the table and also learn and grow in new ways.” This interdisciplinary thinking is a hallmark of not just Bass Connections, but Duke as a research institution, and it’s clear that this spirit is alive and well, even virtually.
Herman Pontzer explains where our calories really go, and what studying humanity’s past can teach us about staying healthy today.
Duke professor Herman Pontzer has spent his career counting calories. Not because he’s watching his waistline, exactly. But because, as he sees it, “in the economics of life, calories are the currency.” Every minute, everything the body does — growing, moving, fighting infection, even just existing — “all of it takes energy,” Pontzer says.
In his new book, “Burn,” the evolutionary anthropologist recounts the 10-plus years he and his colleagues have spent measuring the metabolisms of people ranging from ultra-athletes to office workers, as well as those of our closest animal relatives, and some of the surprising insights the research has revealed along the way.
Much of his work takes him to Tanzania, where members of the Hadza tribe still get their food the way our ancestors did — by hunting and gathering. By setting out on foot each day to hunt zebra and antelope or forage for berries and tubers, without guns or electricity or domesticated animals to lighten the load, the Hadza get more physical activity each day than most Westerners get in a week.
So they must burn more calories, right? Wrong.
Pontzer and his colleagues have found that, despite their high activity levels, the Hadza don’t burn more energy per day than sedentary people in the U.S. and Europe.
These and other recent findings are changing the way we understand the links between energy expenditure, exercise and diet. For example, we’ve all been told that if we want to burn more calories and fight fat, we need to work out to boost our metabolism. But Pontzer says it’s not so simple.
“Our metabolic engines were not crafted by millions of years of evolution to guarantee a beach-ready bikini body,” Pontzer says. But rather, our metabolism has been primed “to pack on more fat than any other ape.” What’s more, our metabolism responds to changes in exercise and diet in ways that thwart our efforts to shed pounds.
What this means, Pontzer says, is you can walk 16,000 steps each day like the Hadza and you won’t lose weight. Sure, if you run a marathon tomorrow you’ll burn more energy than you did today. But over time, metabolism responds to changes in activity to keep the total energy you spend in check.
Pontzer’s book is more than a romp through the Krebs cycle. For anyone suffering pandemic-induced pangs of frustrated wanderlust, it’s also filled with adventure. He takes readers on an hours-long trek to watch a Hadza man track a wounded giraffe across the savannah, to the rainforests of Uganda to study climbing chimpanzees, and to the foothills of the Caucasus Mountains to unearth the 1.8 million-year-old remains of some of the first people who trekked out of Africa.
His humor shines through along the way. Even when awoken by a chorus of 300-pound lions just a few hundred yards from his tent, he stops to ponder whether his own stench gives him away, and what he might do if they come for his “soft American carcass, the warm triple crème brie of human flesh.”
Pontzer spoke via email with Duke Today about his book:
Q: What’s the lesson the Hadza and other hunter-gatherers teach us about managing weight and staying healthy?
A: The Hadza stay incredibly fit and healthy throughout their lives, even into their older ages (60’s, 70’s, even 80’s). They don’t develop heart disease, diabetes, obesity, or the other diseases that we in the industrialized world are most likely to suffer from. They also have an incredibly active lifestyle, getting more physical activity in a typical day than most Americans get in a week.
My work with the Hadza showed that, surprisingly, even though they are so physically active, Hadza men and women burn the same number of calories each day as men and women in the U.S. and other industrialized countries. Instead of increasing the calories burned per day, the Hadza physical activity was changing the way they spend their calories — more on activity, less on other, unseen tasks in the body.
The takeaway for us here in the industrialized world is that we need to stay active to stay healthy, but we can’t count on exercise to increase our daily calorie burn. Our bodies adjust, keeping energy expenditure in a narrow range regardless of lifestyle. And that means that we need to focus on diet and the calories we consume in order to manage our weight. At the end of the day, our weight is a matter of calories eaten versus calories burned — and it’s really hard to change the calories we burn!
Q: You’re saying that exercise doesn’t matter? What’s the point, if we can’t eat that donut?
A: All those adjustments our bodies make responding to exercise are really important for our health! When we burn more calories on exercise, our bodies spend less energy on inflammation, stress reactivity (like cortisol), and other things that make us sick.
Q: What’s the biggest misunderstanding about human metabolism?
A: We’re told — through fitness magazines, diet fads, online calorie counters — that the energy we burn each day is under our control: if we exercise more, we’ll burn more calories and burn off fat. It’s not that simple! Your body is a clever, dynamic product of evolution, shifting and adapting to changes in our lifestyle.
Q: In your book you say we’re driven to magical thinking when it comes to calories. What do you mean by that?
A: Because our body is so clever and dynamic, and because humans are just bad at keeping track of what we eat, it’s awfully hard to keep track of the calories we consume and burn each day. That, along with the proliferation of fad diets and get-thin-quick schemes, has led to this idea that “calories don’t matter.” That’s magical thinking. Every ounce of your body — including every calorie of fat you carry — is food you consumed and didn’t burn off. If we want to lose weight, we must eat fewer calories than we burn. It really comes down to that.
Q: Some people say that if the cavemen didn’t eat it, we shouldn’t either. What does research show about what foods are “natural” for humans to eat?
A: There’s no singular, natural human diet. Hunter-gatherers like the Hadza eat a diverse mix of plant and animal foods that varies day to day, month to month, and year to year. There’s even more dietary diversity when we look across populations. Humans are built to thrive on a wide variety of diets — just about everything is on the menu.
That said, the ultra-processed foods we’re inundated with in our modern industrialized world really are unnatural. There are no Twinkies to forage in the wild. Those foods are literally engineered to be overconsumed, with a mix of flavors that overwhelm our brain’s ability to regulate our appetites. Now, it is still possible to lose weight on a Twinkie diet (I’m not recommending it!), if you’re very strict about the calories eaten per day. But we need to be really careful about how we incorporate ultra-processed foods into our daily diets, because they are calorie bombs that drive us to overconsume.
Q: If we could time travel, what would our hunter-gatherer ancestors make of our industrialized diet today?
A: We don’t even need to imagine — We are those hunter-gatherers! Biologically, genetically, we are the same species that we were a hundred thousand years ago, when hunting and gathering were the only game in town. When we’re confronted with modern ultra-processed foods, we struggle. They are engineered to be delicious, and we tend to overconsume.
Q: Has the COVID-19 pandemic brought any of these lessons home for you? What can we do to keep active and watch what we eat, even while working from home?
The pandemic has been a tragedy on so many levels — the loss of life, those suffering with long-term effects, the social and economic impacts. The impact on diet and exercise have been bad as well, for many of us. Stress eating is a real phenomenon, and the stress and emotional toll of the pandemic — along with having easy access to the snacks in our kitchen — have led many to gain weight. Physical activity seems to have declined for many. There aren’t easy answers, but we should try to make a point to get active every day. And we can help ourselves make better decisions about food by keeping ultra-processed foods out of our houses. You can’t plow through a bag of chips if you don’t have chips in your cupboard.
Q: You’ve measured the energy costs of activities ranging from taking a breath to doing an Ironman. What is one of the more extreme or surprising calorie-burning activities that you’ve measured, or would like to measure, in humans or some other animal?
A: With colleagues from Japan, I measured the energy cost of a heartbeat – a tricky bit of metabolic measurement! Turns out each beat of your heart burns about 1/300th of a kilocalorie! Amazing how efficient our bodies can be.
Q: What is something people have questions about that we just don’t know the answer to yet? What would it take to find out?
A: Right now we’re excited about measuring the adjustments our bodies make when we increase our exercise: how exactly does burning more energy on physical activity impact our immune system, our stress response, our reproductive system? It will take a long-term study of exercise to see how these systems change over time.
Most people at Duke are familiar with Bass Connections, the powerhouse interdisciplinary research program that brings together students and faculty from a wide variety of backgrounds to tackle complex problems.
Like most people, when the country went on COVID-19 pandemic lockdown, team leaders and members within Bass Connections needed to adapt their approach.
Instead of merely adapting, though, some Bass Connections teams saw a problem-solving opportunity. They pivoted to address some of the most pressing problems that the pandemic has created or exacerbated. On Tuesday, March 2nd, eight teams gathered to present their research at the first Bass Connections Works in Progress Symposium.
These teams tackled issues ranging from the ethics of contact tracing to the availability and access to contraception.
One team focused on the issue of food security amongst Latinx populations in Durham. Their presentation was lead by Elaijah Lapay, Faraan Rahim, and Karina Moreno Bueno. The team aimed to tackle three major goals: “How is the pandemic affecting the food security of Latinx residents, and how do environmental public health factors contribute to this population’s risk for COVID-19 infection? How does the incorporation of fresh, local foods mitigate these effects? How is the pandemic affecting the food assistance services locally, nationally, and internationally for the Latinx community?”
Of the Hispanic/Latinx respondents to the 2019 Durham Community Health Survey, 20.9% said they sometimes skipped or limited their meals. Combining that with the fact that 36% of the total number of COVID-19 cases in Durham have been within the Hispanic population, it’s fairly clear that there is a link between food security and health outcomes.
To this end, the Bass Connections team partnered with Root Causes to help advance their project goals through Root Cause’s Fresh Produce Program. Root Causes is an organization started by Duke Medical School students prior to the pandemic that previously provided fresh produce to food-insecure patients at the Duke Outpatient Clinic. But in order to adapt to contactless delivery and new needs due to COVID-19, Root Causes and the Bass team partnered to expand its reach to nearly 150 households in Durham.
This expansion was aided immensely by the Duke Campus Farm, which despite the pandemic mobilized to change the produce it grew to be more culturally relevant to the households they were supporting.
In the future, the team hopes to continue to expand their survey data in the Triangle and continue to assess the impact of the Fresh Produce Program.
The 2020 election saw more people than ever relying on absentee voting, either by the one-stop process or by voting through mail. However, this team aimed to address the many voters that are disenfranchised because their votes are rejected due to errors in their ballot. While NC courts ruled that voters are required to be notified if their ballot needs curing, the difficulty of curing one’s ballot often dissuades people from even starting the process, leading to those votes not being counted.
The team utilized the app BallotTrax, a company that the North Carolina State Board of Elections hired to track these ballots. The team then focused on phone banking to increase BallotTrax usage, and then analyzed voter outcomes.
In the future, they hope to analyze the effect that BallotTrax outreach had on voting success, the efficacy of BallotTrax for voters in North Carolina, and the efficiency of North Carolina’s vote-by-mail system compared to other states.
A goal of this symposium for many teams was to ask audience members for suggestions on ways to direct their research further. The beauty of seeing research midway through the process is that it opens the door for collaborative thinking, out-of-the-box ideas, and being open about obstacles and mistakes.
This virtual Symposium is a testament not just to Duke’s collaborative research spirit, which is alive and well despite the pandemic, but to the adaptability of Duke student researchers and faculty. There’s no doubt that these eight Bass Connections Teams, among the many other teams part of the program this year, have been generating relevant and impactful knowledge and will continue to do so.
Home values and race have an intimate connection in Durham, NC. From 1940 to 2020, if mean home values in Black-majority Census tracts had appreciated at rates equal to those in white Census tracts, the mean home value for homes in Black tracts would be $94,642 higher than it is.
That’s the disappointing, but perhaps not shocking, finding of a Duke Data+ team.
Because housing accounts for the biggest portion of wealth for families that fall outside of the top 10% of wealth in the U.S., this figure on home values represents a pervasive racial divide in wealth.
The team used a multitude of data to conduct their analyses, including the 1940 Census, Durham County records, CoreLogic data for home sales and NC voter registrations. Aside from the nearly $100,000 difference between mean home values between Black census tracts (defined as >50% Black homeowners from 1940-2020) and white census tracts (defined as >50% white homeowners from 1940-2020), Ali, Datto, and Zhou also found that over the last 10 years, home values have risen in Black neighborhoods as they have been losing Black residents. Within Census tracts, the team said that Black home-buyers in Durham occupy the least valuable homes.
Datto introduced the concept of redlining — systemic housing discrimination — and explained how this historic issue persists. From 1930-1940, the Home Owners’ Loan Corporation (HOLC) and Federal Housing Administration (FHA) designated certain neighborhoods unsuitable for mortgage lending. Neighborhoods were given a desirability grade from A to D, with D being the lowest.
In 1940, no neighborhoods with Black residents were designated as either A or B districts. That meant areas with non-white residents were considered more risky and thus less likely to receive FHA-guaranteed mortgages.
Datto explained that these historic classifications persist because the team found significant differences in the amount of accumulated home value over time by neighborhood rating. We are “seeing long-lasting effects of these redlined maps on homeowners in Durham, “ said Datto, with even “significant differences between white [and non-white] homeowners, even in C and D neighborhoods.”
Zhou explained the significance of tracking the changes of each Census tract – Black, white, or integrated – over the last 50 years. The “white-black disparity [in home value] has grown by 287%” in this time period, he said. Homes of comparable structural design and apparent worth are much less valuable for simply existing in Black neighborhoods and being owned by Black people. And the problem has only expanded.
Along with differences in home value, both Black and white neighborhoods have seen a decline in Black homeowners in the 21st Century, pointing to a larger issue at hand. Though the work done so far merely documents these trends, rather than looking for correlation that may get at the underlying causes of the home-value disparity, the trends pair closely with other regions across the country being impacted by gentrification.
“Home values are going up in Black neighborhoods, but the number of Black people in those neighborhoods is going down,” said Datto.
Ali pointed out that there are evaluation practices that include evaluation of the neighborhood “as opposed to the structural properties of the home.” When a house is being evaluated, he said a home of similar structure owned by white homeowners would never be chosen as a comparator for a Latinx- or Black-owned home. This perpetuates historical disparities, as “minority neighborhoods have been historically undervalued” it is a compounding, systemic cycle.
The team hopes to export their methodology to a much larger scale. Thus far, this has presented some back-end issues with data and computer science, however “there is nothing in the analysis itself that couldn’t be [applied to other geographical locations,” they said.
Large socioeconomic racial disparities prevail in the U.S., from gaps in unemployment to infant mortality to incarceration rates to life expectancy itself. Though it should come as no surprise that home-values represent another area of inequity, work like Ali, Datto, and Zhou are conducting needs more traction, support, and expansion.
We offered fruit-eating ruffed lemurs at the Duke Lemur Center fresh lettuce each afternoon for 10 days. They happily ate it and their gut microbiomes shifted, suggesting that leafy greens could be incorporated into the lemurs’ standard dietary regimen to boost foraging opportunity and fiber intake.
Red-ruffed lemurs and black-and-white ruffed lemurs are some of Madagascar’s most iconic wildlife. Sporting a long snout and a neck ruff to rival those of the Elizabethan court, these primates naturally live in the rainforests, where they mostly eat fruits and flowers, and make their living as seed dispersers and pollinators.
Ruffed lemurs also live in zoos worldwide, where they are given fruit-rich diets to match those foraged by their wild peers. But scientists are starting to realize that the fruit eaten by wild lemurs is quite different from the domesticated fruit provided at zoos. Wild fruits are seedy, pulpy, and thick-skinned, whereas orchard fruits are fleshy, plump, and sweet. From a nutritional standpoint, wild fruits contain more fiber, whereas orchard fruits contain more sugar.
Our team wondered if a fiber boost might benefit Duke’s ruffed lemur colony. But would these fruit-loving lemurs eat their veggies?
Cue the salad bar.
To test this idea, we offered ruffed lemurs at the Duke Lemur Center a lot of lettuce. Lettuce seemed like a pretty palatable way to stimulate foraging behavior, while boosting fiber intake.
With help from the research department, we offered 19 ruffed lemurs 150-200 grams of romaine lettuce each day, which is about double the weight of their standard diet. We repeated this regimen every day for 10 days, while recording the lemurs’ feeding behavior and collecting fecal samples for gut microbiome analysis. Because gut microbes are chiefly responsible for converting plant fiber into energy for the lemurs, measuring changes to the lemurs’ microbiomes offered a way to ‘see’ the impact of lettuce consumption.
It turns out that ruffed lemurs really like lettuce. They consistently ate lettuce every day and showed no decline in consumption across the study. Younger animals ate more lettuce than did geriatric lemurs, but all lemurs spent more time crunching on lettuce stalks than the leaves.
And their gut microbiomes responded. We noted two microbes that were more abundant on the lettuce diet: a known fiber digester from the Ruminococcaceae family, and a microbe known for its positive association with host health in other animals called Akkermansia.
Despite their classification as fruit eaters, ruffed lemurs readily eat lettuce. We think lettuce can be used to extend the lemurs’ foraging time while boosting dietary fiber. And it might just help replicate the lifestyles experienced by wild ruffed lemurs in their native Malagasy rainforests. At the Duke Lemur Center, lettuce is now a routine item offered to ruffed lemurs (and other species too!). Next time you come out for a tour (once it’s safe to do so), you might get to see them crunching away on their new favorite snack!
Like wine, cheese, and savvy financial investments, many tropical trees become more valuable with age. This is particularly true when it comes to carbon storage, because old trees are often the biggest trees and the larger the tree, the more carbon it stores.
The value of big, old trees in combating climate change was underscored in a recent study of Gabon’s forests, led by the Nicholas School of the Environment’s John Poulsen. The team’s striking finding — that half of Gabon’s wealth of carbon is found in the largest 5% of trees — has implications that reach far beyond the sparsely populated Central African country’s borders.
Tropical forests play a key role in the global carbon cycle by keeping carbon out of the atmosphere. Trees take in CO2 — one of the infamous, heat-trapping greenhouse gases — during photosynthesis and use the carbon to grow, making new leaves, thicker and taller trunks, and more expansive root systems.
Scientists can estimate how much carbon a tree holds by measuring its trunk. So, like rainforest tailors, trained technicians traveled to all corners of the country to measure the girth and height of tens of thousands of trees.
This extraordinary two-year long effort was one of the first nationwide forest inventories in the tropics, making Gabon a leader in comprehensive forest monitoring.
Poulsen and collaborators used the tree measurements to estimate the amount of carbon stored in Gabon’s forests and to determine why some forests hold more carbon than others.
“The field techs deserve all the credit”, Poulsen explained, “as they often walked for days through thick forest, traversing swamps and enduring humid, buggy conditions to measure trees. We turned their sweat and toil into information that could be used by Gabon’s government to prioritize areas for conservation.”
The team analyzed a suite of environmental factors to see their effects on carbon storage. Of the natural factors, only soil fertility had a noticeable positive effect on tree biomass. Much more important was the impact of humans. As human activities such as agriculture and logging tend to target large trees, more heavily human-disturbed forests had a much different structure than pristine forests. The farther a study area was from human settlements, the more likely it was to host large trees and consequently, higher amounts of carbon.
The paper notes that Gabon stands out as a country with “one of the highest densities of aboveground forest carbon.” In fact, Gabon’s undisturbed forests store more carbon than those in the Amazon, which have been referred to as the lungs of the planet.
According to Poulsen, “Gabon is the second most forested country in the world with 87% forest cover, a deforestation rate near zero…” Because of its impressive forest cover and its location straddling the equator, Gabon’s forests host an incredibly diverse array of plants and animals, including many threatened and endangered species. Rural communities depend on these forests for their livelihoods.
However, Gabon’s impressive forests are valuable to more than just wildlife, climate researchers, and local communities. The logging industry also sees these forests as a chance for profit. More than half (about 67%) of Gabon’s forests are under contract with logging companies to harvest timber, putting them at risk of losing many of their carbon-storing giants.
Poulsen’s study highlights the importance of a more nuanced approach to forest conservation in Gabon. One that doesn’t simply focus on stopping deforestation or promoting restoration, as is prescribed in many international climate change plans, but an approach that recognizes the necessity of preserving high conservation value, old growth forests.
Guest Post by Anna Nordseth, a graduate student in the Nicholas School of the Environment.
Imagine for a moment that you’re 6,000 pounds, living in one of the wildest places on Earth, with no schedule, nowhere to be. How do you decide where to spend your time? Where to go next? Do you move where food is most plentiful? Is water your main priority?
These are some of the questions addressed by Duke Ph.D. candidate Amelia Meier and former postdoctoral researcher Dr. Chris Beirne in Dr. John Poulsen’s lab. Their recent study published in Trends in Ecology and Evolution focused on the African forest elephant–the slightly smaller yet still undeniably huge cousin of the savanna elephant.
The team wanted to know what influences certain aspects of elephant behavior. Specifically, how much climate and resource availability drives elephant movement and influences their diet. To do this, the team looked at fruit abundance (a high-energy staple of elephants’ diets), water availability from rainfall, and elephant identity and how those factors affect how an individual moves and eats.
One might think that such a massive animal is easy to spot in the forest. However, the dense vegetation of Central African rainforests can be an impenetrable wall, allowing the massive animals to move unseen through the forest, leaving broken branches and steaming dung piles in their wake.
To better track them, the researchers fitted individual elephants with GPS collars that turn an iPhone into an elephant-tracking tool. This also allowed trackers to follow the elephants at a distance and avoid conflict with the sometimes temperamental animals.
Meier, Beirne, and colleagues also wanted to know more about the diets of the tracked elephants to see if what they ate changed with how much fruit is available. This less-than-glamorous job was done by dissecting fresh dung piles, estimating the proportions of leafy and woody material, and counting the number of seeds in each one.
Tropical rainforests are lush, yet have patchy resources, making it important for many frugivores to have flexible diets. Some trees only produce fruit in the wet season. Others fruit every other year. To gauge fruit availability, the research team conducted “fruit-walks” at the beginning and end of each day of following an elephant, in which trackers counted all of the ripe fruit on the ground.
A key finding of the study was that the most important factor driving movement was an elephant’s individuality; some respond to food or water availability differently and some simply move around more than others.
Interestingly, elephants appear to be affected by resources differently depending on the timescale the authors looked at. Water was important on both a day-to-day and month-to-month basis. Yet on a daily basis, fruit and water were more equally matched, with water still maintaining a slight lead.
Fruit availability was also critical in determining how much elephants moved and what they ate. When there was more fruit available, the elephants ate more fruit, as evidenced by the proportion of seeds in dissected dung piles.
Aside from being an awe-inspiring species, forest elephants are important to the health of their native ecosystems. They are unwitting gardeners, planting seeds of the fruits they consume in piles of dung and giving those seeds a better chance of survival. That’s part of why understanding what motivates forest elephant movement is more than the satisfaction of an elephant enthusiast’s curiosity; it is critical to managing and conserving a species that is vulnerable to multiple threats from humans.
Meier’s dissertation research focuses on elephant social behavior and the effects of human disturbance on elephant social groups, allowing her to pursue her long-term interest in animal behavior with a practical conservation application.
“I was living in Congo and I knew I wanted to keep working in the region. There, you have elephants–this amazing, highly intelligent, social species that is surrounded by conflict.”
Poachers seek elephants for their ivory tusks, which are valuable on the black market. The pachyderms are also prone to conflict with humans when they start foraging in village plantations, destroying crops and damaging livelihoods.
The team’s findings open the way for new questions about why different elephants exhibit different patterns of movement. What underlying factors affect behavior, and why? Does it have to do with age? Sex? Their social environment?
These questions remain unanswered for now, but the work of Meier and colleagues represents a critical step in understanding elephant behavior to improve forest elephant management and conservation strategies.
Guest Post by Anna Nordseth, a Ph.D. Candidate in the Nicholas School of the Environment
Humans have conquered smallpox and drastically reduced child mortality rates, yet we now face problems never seen before. Conditions like heart disease, obesity, cancer, and diabetes pose serious threats to our health. How can we overcome them? The answer may lie in our past.
Herman Pontzer, an associate professor of evolutionary anthropology at Duke, thinks we have something to learn by looking at hunter gatherers.
For most of human evolution, we had to work for our food. Recent developments like supermarkets and cities are strange and have flipped the script on daily life. Pontzer believes if we could live more like our ancestors, maybe we wouldn’t get sick.
Pontzer started off by studying a hunter gatherer group in Tanzania known as the Hadza. The Hadza cling tight to cultural traditions and live off the land in the African savannah. There are no domesticated animals, no guns, and no vehicles. Women spend their days digging for fibrous tubers and gathering berries and baobab fruits. When men aren’t hunting game, they collect honey. Honey plays a major role in the Hadza diet — around 15-20% of their caloric intake.
The Hadza live a very active lifestyle. They walk between 13,000 and 20,000 steps a day, compared to the generic Fitbit goal of 10,000 steps (which most of us don’t even meet, if we’re being honest).
Curious to see if the Hadza’s vigorous activity levels had something to do with their superior health, Pontzer used the doubly labeled water technique to measure total energy expenditure. Shockingly, he found that Hadza and Americans burn the same amount of calories on average.
All our lives we’ve been told exercise converts to burned calories. But evidence from the Hadza tells us this is not the case. What really happens is natural systems in our body adjust to suppress other activity, keeping total expenditure constant. This means that exercise alone is an ineffective tool for weight loss. But don’t quit the gym quite yet — while the Hadza spend most of their total energy being active, an inactive body will spend it on unhealthy things such as inflammation and stress reactivity. This constrained energy mechanism makes exercise essential for overall health. But in the words of Pontzer, “in order to end obesity, we need to fix our diet.”
The idea that the “paleo diet” is necessarily low-carb is a myth, Pontzer says. Hadza rely heavily on starches and fructose for sustenance. Furthermore, what you eat as a hunter gatherer is entirely dependent on geographical location. Hunter gatherer diets do things in common, though: they eat no processed foods, and energy dense foods are hard to come by.
Never before have we had so much food high in energy available at such a low effort. In supermarkets, the cheapest food is the most rich in energy. In the wild, it’s the complete opposite. Pontzer says, “traditional diets are diverse, modern diets are perverse.”
He calculated that an American can get twenty times as much food energy in an hour’s work as a Hadza could with the same effort. Plus, the Hadza don’t have irresistible Doritos they can’t stop eating. When the Hadza are full, they’re full.
The Hadza are naturally protected from the same “diseases of civilization” that we are likely to die from. A beautiful combination of diet and how they expend energy provides a shield that modernization seems to have taken from us. Energy has become too available. But staying healthy is still in our control. It’s about finding the right balance of exercise and eating right.
There is still a lot to be learned from hunter gatherer societies. For now, let the Hadza inspire you to get outside, get active, and cut out processed foods!
It’s 1 PM and you’re only halfway
through a 6-hour hike, climbing in steep terrain under a 100° cloudless sky.
Your water bottle is nearly empty, and you’ve heard the worst of this hike is
yet to come.
And then, just as you are making
peace with the fact that you may collapse from dehydration at any second, you approach
a small river. The germaphobe side of your brain is shouting for you not to
drink from that. The dehydrated animal in you, however, is seriously considering
What do you do?
That is the question that Dr. Caroline
Amoroso and her collaborators from Duke’s department of evolutionary anthropology,
set out to answer. With a slight difference: rather than unprepared hikers, they
asked that question to red-fronted lemurs in Madagascar.
Although we often associate
Madagascar with lush forests, some regions have a very marked dry season during
which water becomes a limited resource. Water holes are few and far apart.
“On my first visit to Kirindy
forest I was amazed at how these waterholes – which are essentially just
puddles of standing water – serve as a source of life for so many animals,”
However, with animals, comes poop.
Throughout the season, these water holes quickly become contaminated with fecal
matter from all the mammals, birds and reptiles that come have a drink. Amoroso
says that fecal contamination was easily detectable even to human observers. “Approaching
some waterholes I could tell that lemurs had been there recently because their
droppings left such a smell!”
By experimentally manipulating
water quality, following groups of radio-collared lemurs and observing lemur
behavior at natural water holes, Amoroso and her team found that, all else
being equal, lemurs prefer to drink clean water.
Indeed, when offered the choice
between a bucket of clean water and a bucket of water containing lemur feces that
had been disinfected by boiling, to kill all possible pathogens, lemurs virtually
always drank from the clean water bucket. When the buckets were removed and
lemurs had to go visit natural water holes, however, they prioritized water
holes closer to their resting site, even if they were more contaminated than
further ones. Proximity was more important than cleanliness, but if multiple
water holes were at similar distances, then lemurs seem to choose the least-contaminated
“I was surprised to find evidence
that the lemurs chose natural waterholes with lower levels of fecal
contamination,” says Amoroso. “I thought that [in a natural setting] avoidance
of fecal contamination would be relatively low on the lemurs’ list of priorities.”
The authors highlight that many
other factors can influence a lemur’s choice of water hole, such as exposure to
potential predators or visits by competing groups. Indeed, Amoroso says that
drinking water can be a very risky business for lemurs: “Lemurs would spend
upwards of thirty minutes scanning the vegetation nervously and making sure
there was no sign of predators before approaching the waterhole and drinking.”
Lemurs prefer clean water, unless
it’s too much trouble. In that hike you were on? Lemurs would definitely drink
from the river.
Guest Post by Marie Claire Chelini, a postdoctoral fellow in evolutionary anthropology.
About 70% of the human body is made up of water. Water is something we consume on a daily basis. Therefore, when a community’s water source is threatened or contaminated it can be extremely detrimental.
In 2017, it became apparent that there was water contamination in eastern North Carolina. Specifically, PFAS or per- and polyfluoroalkyl Alkyl chemicals were found in the water supply. As a result, several legislative mandates were issued in 2018 establishing a PFAS Testing Network to investigate the contamination.
Lee Ferguson, an Associate Professor of Civil and Environmental Engineering at Duke and Kathleen Gray, a professor at UNC’s Institute for the Environment, are testing PFAS water contamination and communicating any risks to the public.
Gray is part of the network’s risk communication team. She explained that PFASs are hard to address because the health effects are unknown and they have yet to determine a standard or guideline for these substances. However, because this water contamination affects the lives of everyone connected to the water supply it is extremely important to communicate risk to the affected community but without eliciting panic.
Gray explained that people often ask, “Are my family and I safe?” “What can I do to protect myself and my family?” “Why did this happen?” and “Why wasn’t it prevented?”
In the last year Ferguson and his research team have tested 409 sites in North Carolina for PFAS compounds.
He explained that PFAS substances are particularly dangerous because they are non-degradable, potentially toxic and constantly changing. Long-chain PFASs are being replaced by fluorinated alternatives.
Ferguson described this phenomenon as “playing environmental ‘whack-a-mole’ with different substances.”
Ferguson and his testing team have found two contaminated water supply sites in North Carolina. Dangerous contamination is based on the EPA health advisory level of 70ng/Liter. The exceedances were found in Maysville and Orange Water and Sewer Authority. Maysville was able to switch to the Jones County water source once the problem was identified.
New data that came in within the last couple weeks found high month-to-month variability in PFAS in the Haw River near Pittsboro. Ferguson and his team predict that it is coming downstream from a waste treatment plant.
While all of this information may seem very alarming, Gray and Ferguson both reiterated that it is not necessary to panic. Instead, people should make sure they are drinking filtered water or invest in a water filter.
Ferguson added, “The best choice is reverse osmosis.”
Gray and Ferguson presented their work at a SciComm Lunch-and-Learn, a monthly event sponsored by Duke Science & Society Initiative that explores interesting and innovative aspects of science communication. The event is free and open to anyone in the Duke community.