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Tracking Down the Origins of Cystic Fibrosis in Ancient Europe

Human Lungs CF
The airways inside the human lung. (Magic mine/Shutterstock.com)

Imagine the thrill of discovery when more than 10 years of research on the origin of a common genetic disease, cystic fibrosis (CF), results in tracing it to a group of distinct but mysterious Europeans who lived about 5,000 years ago.

CF is the most common, potentially lethal, inherited disease among Caucasians—about one in 40 carry the so-called F508del mutation. Typically only beneficial mutations, which provide a survival advantage, spread widely through a population.

CF hinders the release of digestive enzymes from the pancreas, which triggers malnutrition, causes lung disease that is eventually fatal and produces high levels of salt in sweat that can be life-threatening.

CF Symptom Diagram
Depending on the mutation a patient carries, they may experience some or all symptoms of cystic fibrosis. (Blausen.com staff (2014), CC BY-SA)

In recent years, scientists have revealed many aspects of this deadly lung disease which have led to routine early diagnosis in screened babies, better treatments and longer lives. On the other hand, the scientific community hasn’t been able to figure out when, where and why the mutation became so common. Collaborating with an extraordinary team of European scientists such as David Barton in Ireland and Milan Macek in the Czech Republic, in particular a group of brilliant geneticists in Brest, France led by Emmanuelle Génin and Claude Férec, we believe that we now know where and when the original mutation arose and in which ancient tribe of people.

We share these findings in an article in the European Journal of Human Genetics which represents the culmination of 20 years’ work involving nine countries.

What is cystic fibrosis?

My quest to determine how CF arose and why it’s so common began soon after scientists discovered the CFTR gene causing the disease in 1989. The most common mutation of that gene that causes the disease was called F508del. Two copies of the mutation—one inherited from the mother and the other from the father—caused the lethal disease. But, inheriting just a single copy caused no symptoms, and made the person a “carrier.”

I had been employed at the University of Wisconsin since 1977 as a physician-scientist focusing on the early diagnosis of CF through newborn screening. Before the gene discovery, we identified babies at high risk for CF using a blood test that measured levels of protein called immunoreactive trypsinogen (IRT). High levels of IRT suggested the baby had CF. When I learned of the gene discovery, I was convinced that it would be a game-changer for both screening test development and epidemiological research.

That’s because with the gene we could offer parents a more informative test. We could tell them not just whether their child had CF, but also whether they carried two copies of a CFTR mutation, which caused disease, or just one copy which made them a carrier.

CF Mutation
Parents carrying one good copy of the CF gene (R) and one bad copy of the mutated CF gene (r) are called carriers. When both parents transmit a bad copy of the CF gene to their offspring, the child will suffer from cystic fibrosis. Children who inherit just one bad copy will be carriers like their parents and can transmit the gene to their children. (Cburnett, CC BY-SA)

One might ask what is the connection between studying CF newborn screening and learning about the disease origin. The answer lies in how our research team in Wisconsin transformed a biochemical screening test using the IRT marker to a two-tiered method called IRT/DNA.

Because about 90 percent of CF patients in the U.S. and Europe have at least one F508del mutation, we began analyzing newborn blood for its presence whenever the IRT level was high. But when this two-step IRT/DNA screening is done, not only are patients with the disease diagnosed but also tenfold more infants who are genetic carriers of the disease are identified.

As preconception-, prenatal- and neonatal screening for CF have proliferated during the past two decades, the many thousands of individuals who discovered they were F508del carriers and their concerned parents often raised questions about the origin and significance of carrying this mutation themselves or in their children. Would they suffer with one copy? Was there a health benefit? It has been frustrating for a pediatrician specializing in CF to have no answer for them.

The challenge of finding origin of the CF mutation

I wanted to zero in on when this genetic mutation first starting appearing. Pinpointing this period would allow us to understand how it could have evolved to provide a benefit—at least initially—to those people in Europe who had it. To expand my research, I decided to take a sabbatical and train in epidemiology while taking courses in 1993 at the London School of Hygiene and Tropical Medicine.

The timing was perfect because the field of ancient DNA research was starting to blossom. New breakthrough techniques like the Polymerase Chain Reaction made it possible to study the DNA of mummies and other human archaeological specimens from prehistoric burials. For example, early studies were performed on the DNA from the 5,000-year-old Tyrolean Iceman, which later became known as Ötzi.

Ancient Burial
A typical prehistoric burial in a crouched fetal position. (Philip Farrell, CC BY-SA)

I decided that we might be able to discover the origin of CF by analyzing the DNA in the teeth of Iron Age people buried between 700-100 B.C. in cemeteries throughout Europe.

Using this strategy, I teamed up with archaeologists and anthropologists such as Maria Teschler-Nicolaat the Natural History Museum in Vienna, who provided access to 32 skeletons buried around 350 B.C. near Vienna. Geneticists in France collected DNA from the ancient molars and analyzed the DNA. To our surprise, we discovered the presence of the F508del mutation in DNA from three of 32 skeletons.

This discovery of F508del in Central European Iron Age burials radiocarbon-dated to 350 B.C. suggested to us that the original CF mutation may have arisen earlier. But obtaining Bronze Age and Neolithic specimens for such direct studies proved difficult because fewer burials are available, skeletons are not as well-preserved and each cemetery merely represents a tribe or village. So rather than depend on ancient DNA, we shifted our strategy to examine the genes of modern humans to figure out when this mutation first arose.

Why would a harmful mutation spread?

To find the origin of CF in modern patients, we knew we needed to learn more about the signature mutation—F508del—in people who are carriers or have the disease.

This tiny mutation causes loss of one amino acid out of the 1,480 amino acid chain and changes the shape of a protein on the surface of the cell that moves chloride in and out of the cell. When this protein is mutated, people carrying two copies of it—one from the mother and one from the father—are plagued with thick sticky mucus in their lungs, pancreas and other organs. The mucus in their lungs allows bacteria to thrive, destroying the tissue and eventually causing the lungs to fail. In the pancreas, the thick secretions prevent the gland from delivering the enzymes the body needs to digest food.

So why would such a harmful mutation continue to be transmitted from generation to generation?

Iron and Bronze Age Teeth and Bones
The Natural History Museum in Vienna, Austria, houses a large collection of Iron Age and Bronze Age skeletons which are curated by Dr. Maria Teschler-Nicola. These collections were the source of teeth and bones for investigation of ancient DNA and studies on ‘The Ancient Origin of Cystic Fibrosis.’ (Philip Farrell, CC BY-ND)

A mutation as harmful as F508del would never have survived among people with two copies of the mutated CFTR gene because they likely died soon after birth. On the other hand, those with one mutation may have a survival advantage, as predicted in Darwin’s “survival of the fittest” theory.

Perhaps the best example of a mutation favoring survival under stressful environmental conditions can be found in Africa, where fatal malaria has been endemic for centuries. The parasite that causes malaria infects the red blood cells in which the major constituent is the oxygen-carrying protein hemoglobin. Individuals who carry the normal hemoglobin gene are vulnerable to this mosquito-borne disease. But those who are carriers of the mutated “hemoglobin S” gene, with only one copy, are protected from severe malaria. However two copies of the hemoglobin S gene causes sickle cell disease, which can be fatal.

Here there is a clear advantage to carrying one mutant gene—in fact, about one in 10 Africans carries a single copy. Thus, for many centuries an environmental factor has favored the survival of individuals carrying a single copy of the sickle hemoglobin mutation.

Sickle Cell Gene
Individuals who carry two copies of the sickle cell gene suffer from sickle cell anemia, in which the blood cells become rigid sickle shapes and get stuck in the blood vessels, causing pain. Normal red blood cells are flexible discs that slide easily through vessels. (Designua/Shutterstock.com)

Similarly we wondered whether there was a health benefit to carrying a single copy of this specific CF mutation during exposures to environmentally stressful conditions. Perhaps, we reasoned, that’s why the F508del mutation was common among Caucasian Europeans and Europe-derived populations.

Clues from modern DNA

To figure out the advantage of transmitting a single mutated F508del gene from generation to generation, we first had to determine when and where the mutation arose so that we could uncover the benefit this mutation conferred.

We obtained DNA samples from 190 CF patients bearing F508del and their parents residing in geographically distinct European populations from Ireland to Greece plus a Germany-derived population in the U.S. We then identified a collection of genetic markers—essentially sequences of DNA—within the CF gene and flanking locations on the chromosome. By identifying when these mutations emerged in the populations we studied, we were able to estimate the age of the most recent common ancestor.

Next, by rigorous computer analyses, we estimated the age of the CF mutation in each population residing in the various countries.

Sickle Cell and Malaria
Two copies of the sickle cell gene cause the disease. But carrying one copy reduces the risk of malaria. The gene is widespread among people who live in regions of the world (red) where malaria is endemic. ( ellepigrafica)

We then determined that the age of the oldest common ancestor is between 4,600 and 4,725 years and arose in southwestern Europe, probably in settlements along the Atlantic Ocean and perhaps in the region of France or Portugal. We believe that the mutation spread quickly from there to Britain and Ireland, and then later to central and southeastern European populations such as Greece, where F508del was introduced only about 1,000 years ago.

Who spread the CF mutation throughout Europe?

Thus, our newly published data suggest that the F508del mutation arose in the early Bronze Age and spread from west to southeast Europe during ancient migrations.

Moreover, taking the archaeological record into account, our results allow us to introduce a novel concept by suggesting that a population known as the Bell Beaker folk were the probable migrating population responsible for the early dissemination of F508del in prehistoric Europe. They appeared at the transition from the Late Neolithic period, around 4000 B.C., to the Early Bronze Age during the third millennium B.C. somewhere in Western Europe. They were distinguished by their ceramic beakers, pioneering copper and bronze metallurgy north of the Alps and great mobility. All studies, in fact, show that they were into heavy migration, traveling all over Western Europe.

Bell Beaker Sites
Distribution of Bell Beaker sites throughout Europe. (DieKraft via Wikimedia Commons)

Over approximately 1,000 years, a network of small families and/or elite tribes spread their culture from west to east into regions that correspond closely to the present-day European Union, where the highest incidence of CF is found. Their migrations are linked to the advent of Western and Central European metallurgy, as they manufactured and traded metal goods, especially weapons, while traveling over long distances. It is also speculated that their travels were motivated by establishing marriage networks. Most relevant to our study is evidence that they migrated in a direction and over a time period that fit well with our results. Recent genomic data suggest that both migration and cultural transmission played a major role in diffusion of the “Beaker Complex” and led to a “profound demographic transformation” of Britain and elsewhere after 2400 B.C.

Determining when F508del was first introduced in Europe and discovering where it arose should provide new insights about the high prevalence of carriers—and whether the mutation confers an evolutionary advantage. For instance, Bronze Age Europeans, while migrating extensively, were apparently spared from exposure to endemic infectious diseases or epidemics; thus, protection from an infectious disease, as in the sickle cell mutation, through this genetic mutation seems unlikely.

As more information on Bronze Age people and their practices during migrations become available through archaeological and genomics research, more clues about environmental factors that favored people who had this gene variant should emerge. Then, we may be able to answer questions from patients and parents about why they have a CFTR mutation in their family and what advantage this endows.

Bell Beaker Artifacts
Examples of tools and ceramics created by the Bell Beaker people. (Benutzer:Thomas Ihle via German Wikipedia, CC BY-SA) 

This article was originally published on The Conversation. The ConversationMatthew E. Baker, Professor of Geography and Environmental Systems, University of Maryland, Baltimore County

Is it really healthier to live in the countryside?

But evidence-based research that can help us identify the healthiest environments to live is surprisingly scant. As scientists begin to tease apart the links between well-being and the environment, they are finding that many nuances contribute to and detract from the benefits offered by a certain environment – whether it be a metropolis of millions or a deserted beach.

“What we’re trying to do as a group of researchers around the world is not to promote these things willy-nilly, but to find pro and con evidence on how natural environments – and our increasing detachment from them – might be affecting health and well-being,” says Mathew White, an environmental psychologist at the University of Exeter Medical School.

White and other researchers are revealing that a seemingly countless number of factors determine how our surroundings influence us. These can include a person’s background and life circumstances, the quality and duration of exposure and the activities performed in it.

Generally speaking, evidence suggests that green spaces are good for those of us who live in urban areas. Those who reside near parks or trees tend to enjoy lower levels of ambient air pollution, reduced manmade noise pollution and more cooling effects (something that will become increasingly useful as the planet warms).

Wellington, New Zealand

The research shows that green spaces are good for urban dwellers, which should be welcome news to residents of Wellington, New Zealand (Credit: Getty Images)

Natural spaces are conducive to physical and social activities – both of which are associated with myriad benefits of their own.

Time in nature has been linked to reduced physical markers of stress. When we are out for a stroll or just sitting beneath the trees, our heart rate and blood pressure both tend to go down. We also release more natural ‘killer cells’: lymphocytes that roam throughout the body, hunting down cancerous and virus-infected cells.

Researchers are still trying to determine why this is so, although they do have a number of hypotheses. “One predominate theory is that natural spaces act as a calming backdrop to the busy stimuli of the city,” says Amber Pearson, a health geographer at Michigan State University. “From an evolutionary perspective, we also associate natural things as key resources for survival, so we favour them.”

This does not necessarily mean that urban denizens should all move to the countryside, however.

City residents tend to suffer from more asthma, allergies and depression – but they also tend to be less obese, at a lower suicide risk and are less likely to get killed in an accident

City residents tend to suffer from higher levels of asthmaallergies and depression. But they also tend to be less obese, at a lower risk of suicide and are less likely to get killed in an accident. They lead happier lives as seniors and live longerin general. (Read more aboutfive of the world’s healthiest cities).

City-dwellers live longer than their countryside counterparts and are happier as seniors

City-dwellers live longer than their countryside counterparts and are happier as seniors (Credit: Getty Images)

Although we tend to associate cities with pollution, crime and stress, living in rural locales may entail certain costs as well. Disease-carrying insects and arachnids can detract from the health factor of that otherwise idyllic cabin in Maine, for example.

In other cases, rural pollution poses a major threat. In India, air pollution contributed to the deaths of 1.1 million citizens in 2015 – with rural residents rather than urban ones accounting for 75% of the victims. This is primarily because countryside dwellers are at greater risk of breathing air that is polluted by burning of agricultural fields, wood or cow dung (used for cooking fuel and heat).

Indonesia’s slash and burn-style land clearing likewise causes a blanket of toxic haze that lasts for months and sometimes affects neighbouring countries, including Singapore, Malaysia and Thailand. Meanwhile, smoke pollution from fires lit in South America and southern Africa has been known to make its way around the entire southern hemisphere. (That said, the air in the southern hemisphere is generally cleaner than in the northern hemisphere – simply because there are fewer people living there).

Pollution can kill more people in the countryside than the cities

Because of practices like agricultural clearing, pollution can kill more people in the countryside than even in cities (Credit: Getty Images)

It’s not just developing countries, either: wildfires in the western US are wreaking havoc on air quality, while pollution from fertilizers used on farms are detracting from air quality in Europe, Russia, China and the US.

What about the idea of that pure mountain air? It’s true that black carbon aerosols and particulate matter pollution tends to be lower at higher altitudes. But trying to move above air pollution may cause other issues.

While people who live in in places 2,500m or higher seem to have lower mortality from cardiovascular disease, stroke and some types of cancers, data indicate that they also seem to be at an elevated risk of death from chronic pulmonary disease and from lower respiratory tract infections. This is likely at least in part because cars and other vehicles operate less efficiently at higher altitudes, emitting greater amounts of hydrocarbons and carbon monoxide – which is made even more harmful by the increased solar radiation in such places. Living at a moderate altitude of 1,500 to 2,500 meters, therefore, may be the healthiest choice.

It’s not always true that the higher the altitude, the healthier the place

It’s not always true that the higher the altitude, the healthier the place (Credit: Getty Images)

There is a strong argument to be made for living near the sea – or at least near some body of water

On the other hand, there is a strong argument to be made for living near the sea – or at least near some body of water. Those in the UK who live closer to the ocean, for example, tend to have a better bill of health than those who live inland, taking into account their age and socioeconomic status. This is likely due to a variety of reasons, White says, including the fact that our evolution means we are attracted to the high levels of biodiversity found there (in the past, this would have been a helpful indicator of food sources) and that beaches offer opportunities for daily exercise and vitamin D.

Then there are the psychological benefits. A 2016 study Pearson and her colleagues conducted in Wellington, New Zealand found that residents with ocean views had lower levels of psychological distress. For every 10% increase in how much blue space people could see, the researchers found a one-third point reduction in the population’s average Kessler Psychological Distress Scale (used to predict anxiety and mood disorders), independent of socioeconomic status. Given that finding, Pearson says, “One might expect that a 20 to 30% increase in blue space visibility could shift someone from moderate distress into a lower category.” Pearson found similar results in a follow-up study conducted near the Great Lakes in the US (currently in review), as did White in an upcoming study of Hong Kong residents.

The more ‘blue space’ people saw in their everyday life, the less distress and anxiety

Researchers found that the more ‘blue space’ people saw in their everyday life, the less distress and anxiety they experienced (Credit: Getty Images)

Not everyone can live on the coast, however. So Simon Bell, chair of landscape architecture at the Estonian University of Life Sciences and associate director of the OPENspace Centre at the University of Edinburgh, and his colleagues are testing whether restoring neglected bodies of water throughout Europe can help. They are interviewing residents before and after restoration, including at a rundown beach outside of Tallinn, Estonia and an industrial canal near a Soviet bloc-style apartment complex in Tartu, also Estonia, among other places in Spain, Portugal, Sweden and the UK.

The team’s second analysis of nearly 200 recently redeveloped water sites will allow them to tease out how factors such as climate, weather, pollution levels, smells, seasonality, safety and security, accessibility and more, influence a given water body’s appeal. The ultimate goal, Bell says, is to find “what makes a great blue space.” Once the results are in, he and his colleagues will develop a quality assessment tool for those looking to most effectively restore urban canals, overgrown lakes, former docklands, rivers and other neglected blue spaces to make residents’ lives better.

How much we benefit from even a single visit to the coast depends on a variety of factors

How much we benefit from even a single visit to the coast depends on a variety of factors (Credit: Getty Images)

Still, when it comes to wellbeing, researchers do not know how lakes compare to oceans or how rivers compare to seas. Nor have they compared how beaches in, say, Iceland measure up to those in Florida. What they do know is that complex factors including air and water quality, crowding, temperature and even high and low tides affect how something as seemingly simple as a visit to the beach can influence us.

“There might be a million other important things besides weather and daylight that influence someone in Hawaii versus Finland,” White says.

People who live in less regularly sunny places, like Vermont or Denmark, tend to have higher rates of skin cancer

In terms of health, data also suggest that, counterintuitively, people who live in more intermittently rather than regularly sunny places – Vermont and Minnesota in the US, for example, and Denmark and France – tend to have higher rates of skin cancer, likely because sunscreen is not part of daily routines. (Read more aboutfive countries where people live the longest).

Just as some green and blue spaces may be more beneficial than others, researchers are also coming to realize that the environment’s influence on well-being is not evenly distributed.

People living in lower socioeconomic conditions tend to derive more benefits from natural spaces than wealthy residents, White says. That’s likely because richer people enjoy other health-improving privileges, such as taking holidays and leading generally less stressful lives – a finding with important real-world implications. “Here in the UK, local authorities have a legal obligation to reduce health inequalities. So one way to do that is to improve the park system,” White says. “The poorest will benefit the most.”

A clean, oceanside city like Sydney may be one of the best options

A clean, oceanside city like Sydney may be one of the best options (Credit: Getty Images)

It’s also important to point out that simply moving to a relatively pristine coast or forest will not solve all of our problems. Other life circumstances – losing or gaining a job, marrying or divorcing – have a much greater impact on our health. As White puts it, no matter what environment you’re in, “It’s more important to have a house than to be homeless in a park.”

Bell adds that proximity to nature actually tends to rank low on people’s lists of the most important factors for selecting a place to live, after things like safety, quietness and closeness to key locations like schools and work. But while the benefits of green and blue spaces should not be overplayed on an individual level, they are important for the scale at which they work.

And even so, one takeaway seems obvious: those living in a clean, oceanside city with ready access to nature – think Sydney or Wellington – may have struck the jackpot in terms of the healthiest places to live.

By Rachel Nuwer 1 June 2018

15 Tiny Things That Could Seriously Improve Your Life In Just A Month

1. If a task if going to take you less than a minute to complete, do it as soon as you think of it.

The One-Minute Rule is simple, but it works! Getting out of the habit of putting things off is the easiest way to get shit done.

2. Read for a set amount of time every single day.

Even if it’s 10 or 20 minutes, you’ll either finish or make good progress on a book by the end of the month.

@empowerpuffgurl / Via instagram.com

3. Actually start flossing your teeth at least once a day.

It will be worth it when you don’t have to lie at your next dentist appointment.

4. Try and go to bed at the same time each night, and wake up at a similar time each morning.

Your body loves habits, especially good sleep habits. Set a go-to-bed alarm, as well as a wake-up alarm, and try and stick to both most days.

5. Make your bed each and every morning.

Coming home to a bedroom with a made bed is a pure delight. Once you’re in the habit of making your bed, you won’t be able to believe you ever left the house without doing it.

@inbedstore / Via instagram.com

6. Add one new healthy food or ingredient into your diet.

Adding something healthy feels way better than taking something out of your diet, so choose a new vegetable, grain, or spice and work it into your meal rotation.

7. Find a workout you can do comfortably in your own home, and do it regularly.

Even if it’s just a short routine of push-ups, sit-ups, lunges, and squats, you’ll always have something to do on days you can’t be bothered getting to the gym or a class.

8. Instead of putting things down, put them away.

Leaving things where they don’t belong is how homes get messy. Avoid an hour of tidying up by taking a few seconds to put things away as you finish with them.

@mojkkaa / Via instagram.com

9. Each night, plan what you’re going to wear the next day.

If you find mornings a struggle, try preparing your outfit for the next day, the night before.

10. Practice a new skill or hobby for 10 minutes every day.

Whether it’s watercolor painting, embroidery, violin, or learning a new language, dedicating10 minutes a day to it guarantees you’ll have improved by the end of the month.

@threadhoney / Via instagram.com

11. Save every $5 bill that makes its way into your wallet.

A lot of people swear by this simple money-saving trick. Stash away every $5 note you come across, and enjoy your savings at a later date.

12. Write down three things you’re grateful for each night before bed.

Keeping a gratitude list or journal is a lovely practice that helps highlight all the good things you have going on in your life.

@bujocute / Via instagram.com

13. Try meditating, starting with just three minutes a day.

The first session on the Calm app is just three minutes long. Start there, and see how you feel after a month of daily meditation.

14. Keep track of how much water you’re drinking, and set daily hydration goals.

Most of us aren’t drinking enough water, so keeping a tally of how many glasses you’re having a day is a good way to see if you need to improve your habit.

@rockonrubyxx / Via instagram.com

15. Call someone when you’re having a bad day, whether that person is a friend, family member, or health professional.

Find your person, then get into the habit of calling them to chat more regularly.

@sarachengrocks / Via instagram.com
Gyan Yankovich

Darwinian medicine

Darwinian medicine, field of study that applies the principles of evolutionary biology to problems in medicine and public healthEvolutionary medicine is a nearly synonymous but less-specific designation. Both Darwinian medicine and evolutionary medicine use evolutionary biology to better understand, prevent, and treat human disease. These goals are very different from concerns about the human species pursued under the rubric medical Darwinism in the late 19th and early 20th centuries.

Darwinian medicine, which is named for English naturalist Charles Darwin, whose theory of evolution by natural selectionbecame the foundation of modern evolutionary studies, is not a method of practice or a specialized area of research. Like embryology, evolution provides a basic science foundation for all research and clinical practice. Some applications are very practical, such as using evolutionary modeling to understand antibiotic resistance or the reasons why disease-causing genespersist. Other applications are more fundamental. For example, an evolutionary foundation deepens scientists’ understanding of what disease is, and it explains why the metaphor of the body as a designed machine is inadequate.

Evolutionary applications in medicine are diverse, ranging from established methods such as population genetics to newer attempts to understand why the body has traits, such as the narrow birth canal in females, that leave it vulnerable to disease. Evolutionary explanations can be based on the phylogeny (evolutionary history) of the trait or on its proposed adaptive significance. They can address five kinds of traits acted on by evolution (human traits, human genes, pathogen traits, pathogen genes, and cell lines). The intersection of these two kinds of explanations with five objects of explanation defines 10 areas of work in the field.

Established Applications

Much of Darwinian medicine consists of well-established applications of evolution to medicine. For instance, population genetics is intrinsically based on evolutionary biology, phylogenetic methods have long been useful in medicine, and antibiotic resistance is recognized as an example of natural selection. New methods and data have expanded these applications. In genetics, for example, methods have been developed to identify chromosome locations subjected to strong recent selection, such as locations near the lactase gene that influence whether adults can digest milk. Modern phylogenetic methods use genetic data for diverse tasks, from tracing the specific source of an infection to tracing the genetic heritage of an individual. Informal evolutionary thinking about antibiotic resistance has been replaced by rigorous mathematical models that have major implicationsfor public health.

Developing Applications

Other applications of evolutionary biology to medicine are still developing. In particular, studies to test hypotheses about why natural selection has left the human body vulnerable to disease expanded after 1991, when an article titled “The Dawn of Darwinian medicine,” published in The Quarterly Review of Biology and written by American evolutionary biologist George Williams and physician Randolph Nesse, argued that evolutionary explanations are needed to explain not only why bodies usually work well but also why they have aspects that leave them vulnerable to disease. The major evolutionary reasons that explain why bodies remain vulnerable to disease can be organized into six categories. Mismatches between the environments that humans evolved in and that they now occupy account for the prevalence of substance abuse, obesityhigh blood pressureatherosclerosis, and breast cancer. A second reason for vulnerability is the speed with which infectious organisms evolve ways to deal with antibiotics and the protective defenses of the human body. This process of coevolution results not in benign coexistence but in levels of virulence (ability to damage tissues) shaped to maximize the rate of pathogen spread. Virulence often depends on the route of transmission. For instance, respiratory viruses severe enough to keep victims in bed are likely to be displaced by less-severe strains whose victims are mobile enough to infect others. In contrast, malaria parasites spread faster when they make the host too sick to defend against mosquitoes; thus, malaria tends to be quite virulent.

Vulnerability results also from constraints. For example, the eyes of vertebrates are poorly designed, with a blind spot, and nerves and vessels run between the point where light enters the eye and the retina. The octopus eye, by contrast, has no blind spot. Another constraint is the inevitability of DNAreplication errors. Bodies are also subject to engineering constraints and trade-offs. Bones could be thicker, but bodies would then be heavier and slower. Darwinian medicine emphasizes that nothing in the body can be perfect, since every trait is subject to constraints and trade-offs.

Selection shapes bodies for maximum reproduction rather than health. Usually optimal health and reproduction coincide, but mutations that increase reproduction tend to spread, even if they decrease health and longevity. Higher male than female mortality rates in polygynous species (species that have more than one mate) are an example. In such species an incremental investment in bodily protection and repair increases reproductive fitness more for females than for males.

Additionally, many symptoms are not diseases but protective responses shaped by natural selection. Painfever, cough, and anxiety are aversive and useful responses. Nonetheless, medications can often safely block their expression, because of the “smoke-detector principle.” Humans put up with sensitive smoke detectors set off by making toast because such false alarms are a minor nuisance compared with the huge cost of not being alerted to a fire. Likewise, the cost of many bodily defenses is low compared with the cost of not expressing a defense when it is needed, so the normal mechanisms shaped by natural selection give rise to many false alarms and apparently excessive responses.

Practical Implications

Darwinian medicine has narrowed the gap between evolutionary biology and medicine and contributed to improvements in the understanding of health and disease. Some advances have been straightforward, such as new public health policies based on formal evolutionary models of antibiotic resistance and evolutionarily informed searches for genes that cause disease. Other advances have come from asking new evolutionary questions about why natural selection has left bodies vulnerable to disease. Applications of these advances are less direct, but they may be more fundamental. They encourage new studies of phenomena with enormous clinical importance, such as why males die younger than females and how selection shapes mechanisms that regulate protective responses such as pain and fever. They offer a more fully biological view of the body and disease

Written by Randolph M. Nesse

The Amazon’s solar-powered river bus

Children on the solar canoe on their way to school
Image captionA school commute with a difference

How can you create public transport in the jungle without polluting it? The isolated Achuar peoples of Ecuador have created an ingenious solution.

A couple of hours before dawn in Kapawi, a village in a remote corner of the Ecuadorian Amazon, a group of men gather to drink litres of tea made from the guayusa plant. One by one they then disappear into the dark to vomit.

This ritual, known as guayusada, is designed to purge and energise and culminates in a sharing of dreams from the night.

It was during one of these ceremonies more than half a century ago that a dream was shared of a “canoe of fire”.

And this dream has recently been realised for the Achuar.

Ecuador's solar canoe in the Amazon

Since April 2017, a canoe powered solely by solar energy travels back and forth along the 67-km (42-mile) stretch of the Capahuari and Pastaza rivers that connect the nine isolated settlements that live along their banks.

The boat Tapiatpia – named after a mythical electric eel in the area – gives the Amazon its first solar powered public transport system.

A map of Achuar territory, South East EcuadorImage copyrightALDEA
Image captionAchuar territory, Ecuador

“The solar canoe is an ideal solution for this place because there is a network of interconnected navigable rivers and a great need for alternative transport,” says Oliver Utne, a US environmentalist who has been working with the community since 2011.

The community previously relied entirely on gasoline canoes, known as peque peques, but they are expensive to run and only owned by a few families per village.

The canoe costs passengers just $1 (71p) each per stop, whereas peque peques cost $5-10 in gasoline for the same journey. Gasoline costs five times more here than in the capital Quito because there are no roads and it needs to be flown in.

Solar technician, Oliver Utne
Image captionSolar technician, Oliver Utne

Of course there is an environmental impact too – the canoe means no pollution in one of the world’s richest areas of biodiversity.

With a roof of 32 solar panels mounted on a traditional canoe design of 16 x 2-metre (52 x 7-feet) fibreglass, Tapiaptia carries 18 passengers.

Its navigator, Hilario Saant, tells me how the canoe is changing lives.

Navigator and community elder, Hilario Saant stands on the solar canoe
Image captionNavigator and community elder, Hilario Saant

“We are helping the community when there are sick children. They call me on the radio and we take the children to the health centre,” he says.

Similarly, more children are now at school because it is more affordable, and there are more inter-community sports events too.

Suddenly, our conversation is interrupted by the excited scream of one of our fellow passengers as they spot a school of pink dolphins. Another advantage of the boat is that its relative quiet doesn’t scare the animals.

The solar canoe tied up at a village port
Image captionThe solar canoe tied up at a village port

Back on dry land Julián Ilanes, a leader of the Territory of the Achuar Nationality of Ecuador (NAE), tells me about the wider opportunities provided by the canoe.

Numerous territorial wars have severed the connection between the Achuar in Ecuador and their cousins over the border in Peru. Mr Ilanes hopes to re-establish trade between the two, something that has thus far been economically impossible due to the distance and the cost of gasoline.

“We can bring clothes and rubber from Peru, and they need green bananas, chicken, and peanuts from us,” he explains.

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The Achuar

An Amazonian community who span the Ecuador-Peru border, numbering around 19,000 people in total

Their culture centres on the importance of dreams and visions and they believe in Arutam – the spirit of the rainforest

Semi-nomadic until the arrival of Christian missionaries in the 1940s, they now live in small villages, sustaining themselves through hunting, fishing, and arable farming

Their remote location has allowed them to preserve their lifestyle

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And the canoe helps strengthen the community’s resilience against the construction of roads.

“Having no roads helps us to maintain our culture, to have the wisdom not to forget what the Achuar culture really is,” says René Canelos, a 27-year-old from Sharamentsa, one of the villages served by the canoe.

René Canelos, resident of Sharamentsa village
Image captionRené Canelos, resident of Sharamentsa village

The arrival of roads in indigenous communities in the north of Ecuador and in Peru has led to development and oil exploration, and with it, deforestation.

Ecuador’s government has argued that roads will improve the Achuar’s access to health care and education, so the canoe helps the community prove they can manage without them.

“The neighbours who let the oil companies in not only saw how this destroyed their forests, but also how it created a lot of internal conflicts because not everyone knew how to take advantage of the money that came in,” says Felipe Borman, a traditional canoe manufacturer.

Mr Borman has come to work with the Achuar on a new prototype of the boat because its current engine, originally designed in Germany, is struggling with the Amazon’s hot sandy stick-strewn waters.

The solar canoe cruising the wide rivers in Achuar territory

The ultimate dream for Mr Utne and Mr Saant is a whole network of sustainable solar canoes navigating these ancient Amazonian highways.

“We really think this can be a model for the rest of the Amazon, and also other places around the world where there is difficulty in accessing gasoline, where there is no road network, and there’s ecosystems that the local people are working to preserve,” says Mr Utne.

But he says the key element is that it was designed first and foremost to work locally.

“Personally, I think that large-scale solutions disconnect us, and I think we get to where we are precisely because we are disconnected.”

“What we need is to create local solutions, and if they work, replicate them in other places,” he says.

Members of the Achuar in Sharamentsa village

At the local level, at least, the difference is palpable.

“I love my boat… it’s a dream come true for the Achuar,” says Mr Saant proudly.

“I’m never going to abandon it, I’m going to continue working for the canoe until I die.”

This BBC series was produced with funding from the Skoll Foundation

The 150-year-old story of Sri Lankan tea-making

 

Two tea pluckers work on a plantation in Sri LankaImage copyright  SCHMOO THEUNE

Almost 5% of the population of Sri Lanka work in the billion-dollar tea industry, picking leaves on the mountain slopes and processing the tea in plantation factories.

The cultivation and selling of black tea has shaped the lives of generations of Sri Lankans since 1867.

Documentary photographer Schmoo Theune visited plantations in the country to explore the world of Ceylon tea production.

A tea plantation in Sri LankaImage copyright SCHMOO THEUNE

Tea bushes on mountain slopes are situated above the barracks-style housing which each plantation provides for its workers.

Tea buds must be picked by hand every seven to 14 days, before the leaves grow too tough.

This means the working location can change from day to day, depending on where the buds need to be collected.

The tea leaves are gathered in tarpaulin bags, which are lighter than the traditional wicker baskets that were once used.

A tea plucker in a plantation fieldImage copyright   SCHMOO THEUNE

The leaves are weighed throughout the day and a tea-picker earns 600 Sri Lankan Rupees (LKR), which is approximately £2.70, if they reach the desired quota of 18kg a day.

If they do not meet this target then they are paid 300 LKR (approximately £1.30).

Some plantations use different wage models, such as paying staff monthly and offering temporary loans to employees.

The majority of Sri Lankan tea workers are ethnically Indian Tamils, a people who were transported by the British to work on the plantations.

They differ from Jaffna Tamils who originate from Sri Lanka’s north.

A person travels down a road in a small sunlit valleyImage copyright   SCHMOO THEUNE

Dirt roads connect the workers’ housing to the tea plantations.

Tea bushes are grown on steep hillsides a metre apart.

Altitude affects the flavour of the tea, with higher altitudes producing a more delicately flavoured crop.

This is more highly valued than the robustly flavoured tea produced at lower elevations.

A tea plucker holds out her handsImage copyright   SCHMOO THEUNE

Veteran tea-pickers often have rough callouses on their hands.

The difficult physical nature of the work is causing a shortage of young tea-pickers.

Many daughters are choosing to work in garment factories, or abroad in domestic roles, rather than the fields of the plantations.

There can be four different levels of hierarchy on a small plantation, ranging from the owner down to tea-pickers.

Each layer supervises the level below it.

The sun sets over worker houses on a tea plantation near Kandy.Image copyright   SCHMOO THEUNE

Some of the houses the workers live in were built by the British during a housing boom in the 1920s when about 20,000 rooms were built for tea-pickers.

The buildings have changed little since.

Families raise their children in a village setting in colourful barracks-style houses.

Many buildings only have electricity or running water for a few hours each day, or do not have them at all.

Many daily tasks such as washing or bathing are carried out in streams and rivers.

Families walk outside their houses next to a tea plantation.Image copyright  SCHMOO THEUNE
The side of a tea plantation houseImage copyright   SCHMOO THEUNE
A woman collects water in containers outside her houseImage copyright   SCHMOO THEUNE

Some areas of housing are supplied with water only once every three days which must be collected in containers.

Tea-pickers and other labourers start work at 7.30am.

In plantation communities, children often have to walk several kilometres to school.

Tea-picking earns relatively low wages, so some tea plantation families have family members who work abroad in the Middle East, or in other cities around Sri Lanka, who send money back home.

A tea plucker poses inside her houseImage copyright   SCHMOO THEUNE

Women who labour on the plantations also have household duties such as cooking, cleaning and taking care of children.

A shelf of food containersImage copyright    SCHMOO THEUNE

The fresh tea leaves are taken to a factory near the plantation for processing, like the one seen below near the Sri Lankan city of Kandy.

A view of a tea plantation factoryImage copyright    SCHMOO THEUNE

‘Withering’ is the first step, requiring the blowing of dry air to extract moisture from the leaf, which gives it a pliable texture.

A batch of 18kg of fresh leaves can yield 5kg of Ceylon tea after it has been processed in plantation factories.

A worker places tea leaves into a machineImage copyright    SCHMOO THEUNE

A rolling machine then twists the withered leaves and begins the fermentation process, which starts to develop the distinctive flavour.

The machinery used in the tea processing is often up to 100 years old.

Finished tea is separated by leaf size, and packaged in bulk bags to be sent for auction in Colombo, the capital of Sri Lanka.

A machine processes tea leavesImage copyright   SCHMOO THEUNE
A woman past a large pile of processed teaImage copyright   SCHMOO THEUNE
Workers work in a tea shop in KandyImage copyright  SCHMOO THEUNE

Ceylon tea is not just an export, it is an essential part of Sri Lankan daily life, consumed by office workers, labourers, students, and everyone in-between.

A tea plucker works on a plantationImage copyright  SCHMOO THEUNE  
BBC News 10 April 2018
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