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Breathing very dirty air may boost obesity risk

Beijing smog

Serious air pollution, like this smog over China’s capital city, may increase the risk of obesity.

Air pollution is bad for our lungs. It may not be great for our waistlines either, a new study in rats finds.

China’s capital city of Beijing has some of the worst air pollution in the world. On really bad days, its air can host more than 10 times as many tiny pollutant particles as the World Health Organization says is safe for human health. In a new study, rats breathed in this air. And those rodents gained more weight, and were unhealthier overall, than were rats breathing much cleaner air. The results suggest that exposure to air pollution can raise the risk of becoming extremely overweight.

And, adds Loren Wold, “It is highly likely that this is happening in humans.”

Wold works at Ohio State University in Columbus. There, he studies how air pollution affects the heart. He was not involved in the new study. But he says it agrees with many other studies that have suggested air pollution can affect metabolism, which is how the body breaks down food and uses it for fuel.

Polluted air contains particles of ash, dust and other chemicals. Sometimes these particles are so numerous that they create a thick, dense smog can cuts visibility.

Earlier experiments among 18-year olds in Southern California had linked heavier traffic with higher body mass index (a measure of overweight and obesity). Areas with heavy traffic also tend to have more of those pollutant particles. Another study found that when pregnant mice were exposed to exhaust from diesel engines, their pups grew up to be heavier. The pups also developed more inflammation in their brains.

In the new study, researchers tested how Beijing’s polluted air affects the health of pregnant rats.

Jim Zhang is an environmental scientist at Duke University in Durham, N.C. He and his co-workers put rats in two indoor chambers in Beijing. They piped polluted air from the city directly into one chamber. Air piped into the other chamber went through a filter. That filter removed almost all of the big pollution particles from the air and about two-thirds of the smaller ones. This made the air more like what people breathe in typical U.S. cities and suburbs, Zhang says.

All rats ate the same type and amount of food. But after 19 days, the pregnant rats breathing the heavily polluted air weighed more than the rats breathing the filtered air. They also had higher amounts of cholesterol — a waxy, fatlike substance — in their blood than did the rats breathing filtered air.

Those breathing the dirtier air had higher levels of inflammation. This is a sign of the body responding to tissue damage. These rats also had higher insulin resistance. This means their bodies weren’t responding as well to insulin, a hormone that helps with using sugar for energy. Insulin resistance can lead to diabetes, a dangerous health condition.

Taken together, the scientists say, these symptoms indicate the rats were developing metabolic syndrome. It’s a condition that puts the animals at risk of heart disease and diabetes.

During the experiment, the pregnant rats gave birth. Their pups stayed in the chambers with their mothers. And young rats that breathed in the polluted air were heavier than pups born to moms living in the cleaner air. Like their moms, the pups breathing very polluted air had more inflammation and insulin resistance.

The longer these pups breathed the dirty air, Zhang says, the more unhealthy they became. This suggests that breathing polluted air for a long time can lead to sickness, Zhang says.

It’s not yet clear exactly how air pollution affects rat metabolism. But it seems, Zhang says, to impair how the animals process fat and sugar. Pollution also increases signs of inflammation in the lungs, blood and fat. Zhang says this is probably what led to weight gain in the animals.

Wold says it might be possible to create medicines that reverse the negative health effects of air pollution. But these medicines will take time to develop.

Until then, Zhang and Wold say that paying attention to air pollution levels can help people manage their health risks. On days when pollution levels are high, they recommend that people stay indoors, if possible — or at least avoid tough outdoor exercise .

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Killer seals develop a taste for shark guts

THAT shark’s fate is sealed. A seal has been spotted turning ecological roles upside-down by killing and eating blue sharks. If this turnabout proves common, ecologists might need to reassess the role of seals in marine ecosystems.

Chris Fallows, a dive-boat operator in Cape Town, South Africa, was photographing 10 blue sharks underwater when a young male Cape fur seal arrived and chased and killed five of them, eating their intestines (African Journal of Marine Science, doi.org/268).

Ordinarily, seals and blue sharks, which are roughly the same size, both prey on much smaller fish, squid and other marine life. Several species of seal also feed on smaller sharks, and blue sharks have been seen pursuing – though not catching – fur seals.

Fallows’s observations are the first time anyone has seen seals preying on such large sharks, says Hugues Benoit of the Canadian Department of Fisheries and Oceans in Moncton, New Brunswick.

Seal attack <i>(Image: Chris Fallows)</i>

Benoit suspects this behaviour is more common than anyone realises. By chowing down on their competitors, seals could alter ocean food webs in unexpected ways, he says. If seals help hold down shark populations, for example, it could boost populations of smaller fish.

If so, fisheries biologists may need to take that into account in managing fish populations.


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Future ruin: Can we design our way out of eco-crisis?

One Central Park in Sydney (Image: James D. Morgan/REX)

Event: Designs of the Year 2015, Design Museum, London

In friendly competition with Percy Bysshe Shelley, the poet Horace Smith once wrote a poem entitled Ozymandias. Shelley’s version is the one we remember, but Smith’s is compelling for another reason. He imagines a hunter traipsing through the ruins of a future London. Lighting upon a fragment of a monument, he “stops to guess/What powerful but unrecorded race/Once dwelt in that annihilated place”.

This year’s Designs of the Year competition has its monumental entries, but even the most grandiloquent of the 76 nominations at least tips its hat to the idea that the world will not sustain another great ruin, or may end up our next great ruin, unless we respond more cleverly to our environment.

Jean Nouvel’s One Central Park in Sydney, Australia, towers above its architectural competitors, literally. Clad in climbing plants by Patrick Blanc, the leading designer of vertical gardens, One Central’s overriding purpose seems to be to apologise for its very existence.

There is even a motorised heliostat mounted on a cantilever near the roof, to erase the building’s shadow. The arrangement looks terrifying in photographs, suggesting the 50-metre-high moon towers of the 19th century when towns experimented with civic lighting.

Giant pot plants

In Ho Chi Minh City, a project called House for Trees eschews apology for action, albeit of a most eccentric sort. Here, high-density living units double as gigantic containers for tropical trees. Come the rains, a sufficient number of these properties could reduce the risk of urban flooding. At least, so claim architects Vo Trong Nghia, although it sounds like special pleading to me – an alibi for the strange green dream they’re weaving, of wandering lost among giant plant pots.

(Image: PITCHAfrica)

Where rains are few, a more down to earth aesthetic holds sway.PITCHAfrica’s Waterbank Campus is a 10-acre school site in Laikipia, Kenya, where 4 acres of irrigated conservation agriculture are fed by 7 low-cost buildings, designed to collect and store what little precipitation there is.

PITCHAfrica’s vision extends beyond unassuming architecture to provide resources like clean water, food and sanitation on-site for its students, in the hope they will spread the word about how to manage scarce resources at home.

This vision, of an artificial “ecosystem capable of empowering and transforming communities”, is shared by a great many of the show’s “technical fix” entries. Take the Blue Diversion toilet. This project, led by the Swiss Federal Institute of Aquatic Science and Technology, and funded by the Bill & Melinda Gates Foundation, is an all-in-one sanitation, fertiliser, drinking-water and biogas solution. In this cheap, ugly, blue plastic toilet, nothing is wasted &ndahs; not even sunlight; there’s a small solar panel on its roof.

Sticking-plaster solution

Other ideas plug in to the smog and mess of cities, and try to make daily life a little more bearable. At the University of Engineering and Technology, Lima, Peru, researchers have invented a billboard that purifies the air in a five-block radius, scrubbing it clean of construction dust and 99 per cent of airborne bacteria – it would take 1200 trees to do the equivalent work, says the team.

Another entry, The Ocean Cleanup, designed by Erwin Zwart with Boyan Slat and Jan de Sonneville, tackles the plastic garbage circulating the world’s oceans. Why not string barriers over the waves to catch the plastic as it moves around? Having raised over U$2 million through crowdfunding, the organisation plans to construct and test large-scale pilot projects.

This is technical fixery at its purest. It doesn’t prevent the oceans being littered: it is an environmental sticking plaster, permitting us to pursue business as usual. But why should designers have to carry the whole world on their shoulders? Designs like these could be part of a broader, political solution. The Ocean Cleanup’s barriers would be a fitting monument for our descendants to puzzle over.

Better, of course, to avoid collapse entirely, but it won’t be simple. It is easier for designers to ameliorate or even disguise problems, rather than to address them head on. Two projects built around the food supply demonstrate this neatly.

Failed lemons

Disclosed (Image: Alexander Gowers)

Disclosed, by Marion Ferrec at the Royal College of Art, in collaboration with Kate Wakely, is a web-based consumer service that allows you to choose products according to your health needs and ethical preferences. Lacking vast wealth, leisure and self-absorption, I won’t be using it.

But neither am I entirely persuaded by Marcel’s humorous campaign for the French supermarket giant Intermarché – a series of beautifully photographed imperfect fruits and vegetables. The idea is to shift ridiculous-looking potatoes, hideous oranges and failed lemons onto the consumer, and thereby reduce food waste. But the campaign preserves and reinforces (by price offers) the very distinction between perfect and imperfect produce that caused the problem in the first place.

It is, frankly, next to impossible to imagine how we get from a wasteful here to a sustainable there – and for that reason alone, I think Alexandra Daisy Ginsberg’s design fiction Designing for the Sixth Extinction is the poster-child of this year’s competition. Ginsberg has anatomised the ultimate disruptive enterprise, in which “nature is totally industrialized for the benefit of society”.

Although her fictional synthetic creatures are deliciously creepy (especially the “biologically-powered mobile soil bioremediation device”) it is her business model of saving our civilisation at the expense of the natural world, while replacing it with something better, that fascinates.

If Ginsberg’s vision comes to pass, our descendants won’t be able to puzzle at our monuments. Our monuments will be everywhere, all around them, and inside them.


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Oceans swallowed 13 million tonnes of plastic in 2010

Vast floating islands of plastic are just a drop in the ocean compared with what’s lurking deeper down. Between 5 and 13 million tonnes of plastic debris entered the marine environment in 2010 – and most of it is under water. What’s more, without improvements in the way we manage waste, it could be 10 times as much each year by 2025.

The visible plastic is just a small proportion of what's in the oceans <i>(Image: Pascal Kobeh/Naturepl.com)</i>

It has been 40 years since the first scientific reports of plastic pollution in the ocean, but we still have plenty to learn. For instance, the combined results from 24 oceanic expeditions published late last year concluded there may beperhaps 244,000 tonnes of floating plastic out there. This is puzzling, because conservative estimates suggest something like 9 million tonnes of plastic have entered the oceans since the 1970s.

Now we know there’s even more missing plastic than that. Jenna Jambeck at the University of Georgia, Athens, and her colleagues have looked at data on plastic use and disposal in 192 coastal countries. They calculate that between 4.8 and 12.7 million tonnes entered the world’s oceans in 2010 alone. This means the amount of plastic that has entered the ocean down the years might be 1000 times more than the mass of floating plastic that scientific surveys have measured.

Surprisingly, the 10 countries with the largest problem – many of which are in south-east Asia – generally have relatively low rates of plastic waste generation per person. For instance, in China – which tops the list with an estimate of up to 3.53 million tonnes of plastic marine debris a year – the average person generates about 1.1 kilograms of waste per day of which just 11 per cent is plastic. In the US – at 20 on the list – the average person generates more than twice as much waste. But the top offending countries also have high coastal populations and low rates of plastic recycling.

It’s an interesting study, says Marcus Eriksen of the Five Gyres Institute in Los Angeles, who led last year’s floating plastic study

– but some of the assumptions used to arrive at the new calculations could be quibbled with. “I believe the authors underestimate the amount of trash that is scavenged, burned and buried before it reaches the ocean,” he says. “I think there’s much less leaving land.”

Even so, there is clearly a huge mismatch between the plastic entering the ocean and the plastic we find there. “The disturbing conclusion is that much of the plastic entering the oceans is unaccounted for,” says Carlos Duarte at the King Abdullah University of Science and Technology in Saudi Arabia, who has also helped conduct surveys into the amount of plastic in the oceans.

Plastic smog

Where is the missing plastic? Perhaps it’s hiding in plain sight. “It’s important to understand that plastic shreds rapidly into microplastics that distribute widely into the most remote waters on the planet,” says Eriksen. “Of the 5.25 trillion particles of plastic we reported recently in PLoS One, 92 per cent are less than the size of a grain of rice.”

Such small particles spread throughout the water column, says Eriksen, also finding their way into sea-floor sediments and ice cores. That means we should stop thinking of plastic waste in terms of unsightly chunks of debris floating in vast oceanic garbage patches, and instead see it more as a pervasive “plastic smog” of tiny particles spread through the entire volume of ocean water.

“It’s not sensible to go to the ocean with nets to capture trash, but rather to focus on mitigation strategies on land,” says Eriksen.

Yet the amount of plastic entering the ocean is likely to keep rising in the years to come. Jambeck and her colleagues point out that 16 of the top 20 plastic producers they identified are middle-income countries, where strong economic growth will probably result in even more plastic use, but where the infrastructure to deal with the waste is still lacking.

But the solution isn’t to burden these developing countries with the cost of building effective waste management infrastructures, says Eriksen. Instead, we should require the plastics industry to rethink the way it designs its products – in particular, the industry should phase out plastic products designed for single use.

Change the way plastic is produced, says Eriksen, “and the plastic pollution issue would largely diminish”.


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26 Pictures Will Make You Re-Evaluate Your Entire Existence

. This is the Earth! This is where you live.

This is the Earth! This is where you live.

NASA Goddard Space Flight Center Image / Via visibleearth.nasa.gov

2. And this is where you live in your neighborhood, the solar system.

And this is where you live in your neighborhood, the solar system.

3. Here’s the distance, to scale, between the Earth and the moon. Doesn’t look too far, does it?

Here's the distance, to scale, between the Earth and the moon. Doesn't look too far, does it?

4. THINK AGAIN. Inside that distance you can fit every planet in our solar system, nice and neatly.

THINK AGAIN. Inside that distance you can fit every planet in our solar system, nice and neatly.

PerplexingPotato / Via reddit.com

5. But let’s talk about planets. That little green smudge is North America on Jupiter.

But let's talk about planets. That little green smudge is North America on Jupiter.

NASA / John Brady / Via astronomycentral.co.uk

6. And here’s the size of Earth (well, six Earths) compared with Saturn:

And here's the size of Earth (well, six Earths) compared with Saturn:

NASA / John Brady / Via astronomycentral.co.uk

7. And just for good measure, here’s what Saturn’s rings would look like if they were around Earth:

And just for good measure, here's what Saturn's rings would look like if they were around Earth:

Ron Miller / Via io9.com

8. This right here is a comet. We just landed a probe on one of those bad boys. Here’s what one looks like compared with Los Angeles:

This right here is a comet. We just landed a probe on one of those bad boys. Here's what one looks like compared with Los Angeles:

Matt Wang / Via mentalfloss.com

9. But that’s nothing compared to our sun. Just remember:

But that's nothing compared to our sun. Just remember:

10. Here’s you from the moon:

Here's you from the moon:

NASA

11. Here’s you from Mars:

Here's you from Mars:

NASA

12. Here’s you from just behind Saturn’s rings:

Here's you from just behind Saturn's rings:

NASA

13. And here’s you from just beyond Neptune, 4 billion miles away.

And here's you from just beyond Neptune, 4 billion miles away.

NASA

To paraphrase Carl Sagan, everyone and everything you have ever known exists on that little speck.

14. Let’s step back a bit. Here’s the size of Earth compared with the size of our sun. Terrifying, right?

Let's step back a bit. Here's the size of Earth compared with the size of our sun. Terrifying, right?

John Brady / Via astronomycentral.co.uk

The sun doesn’t even fit in the image.

15. And here’s that same Sun from the surface of Mars:

And here's that same Sun from the surface of Mars:

NASA

16. But that’s nothing. Again, as Carl once mused, there are more stars in space than there are grains of sand on every beach on Earth:

But that's nothing. Again, as Carl once mused, there are more stars in space than there are grains of sand on every beach on Earth:

17. Which means that there are ones much, much bigger than little wimpy sun. Just look at how tiny and insignificant our sun is:

Which means that there are ones much, much bigger than little wimpy sun. Just look at how tiny and insignificant our sun is:

Our sun probably gets its lunch money stolen.

18. Here’s another look. The biggest star, VY Canis Majoris, is 1,000,000,000 times bigger than our sun:

26 Pictures Will Make You Re-Evaluate Your Entire Existence

………

19. But none of those compares to the size of a galaxy. In fact, if you shrunk the Sun down to the size of a white blood cell and shrunk the Milky Way Galaxy down using the same scale, the Milky Way would be the size of the United States:

But none of those compares to the size of a galaxy. In fact, if you shrunk the Sun down to the size of a white blood cell and shrunk the Milky Way Galaxy down using the same scale, the Milky Way would be the size of the United States:

20. That’s because the Milky Way Galaxy is huge. This is where you live inside there:

That's because the Milky Way Galaxy is huge. This is where you live inside there:

21. But this is all you ever see:

But this is all you ever see:

(That’s not a picture of the Milky Way, but you get the idea.)

22. But even our galaxy is a little runt compared with some others. Here’s the Milky Way compared to IC 1011, 350 million light years away from Earth:

But even our galaxy is a little runt compared with some others. Here's the Milky Way compared to IC 1011, 350 million light years away from Earth:

Just THINK about all that could be inside there.

23. But let’s think bigger. In JUST this picture taken by the Hubble telescope, there are thousands and thousands of galaxies, each containing millions of stars, each with their own planets.

But let's think bigger. In JUST this picture taken by the Hubble telescope, there are thousands and thousands of galaxies, each containing millions of stars, each with their own planets.

24. Here’s one of the galaxies pictured, UDF 423. This galaxy is 10 BILLION light years away. When you look at this picture, you are looking billions of years into the past.

Here's one of the galaxies pictured, UDF 423. This galaxy is 10 BILLION light years away. When you look at this picture, you are looking billions of years into the past.

Some of the other galaxies are thought to have formed only a few hundred million years AFTER the Big Bang.

25. And just keep this in mind — that’s a picture of a very small, small part of the universe. It’s just an insignificant fraction of the night sky.

And just keep this in mind — that's a picture of a very small, small part of the universe. It's just an insignificant fraction of the night sky.

26. And, you know, it’s pretty safe to assume that there are some black holes out there. Here’s the size of a black hole compared with Earth’s orbit, just to terrify you:

And, you know, it's pretty safe to assume that there are some black holes out there. Here's the size of a black hole compared with Earth's orbit, just to terrify you:

D. Benningfield/K. Gebhardt/StarDate / Via mcdonaldobservatory.org

So if you’re ever feeling upset about your favorite show being canceled or the fact that they play Christmas music way too early — just remember…

This is your home.

This is your home.

By Andrew Z. Colvin (Own work) [CC-BY-SA-3.0 (creativecommons.org) or GFDL (gnu.org)], via Wikimedia Commons

This is what happens when you zoom out from your home to your solar system.

This is what happens when you zoom out from your home to your solar system.

And this is what happens when you zoom out farther…

And this is what happens when you zoom out farther...

By Andrew Z. Colvin (Own work) [CC-BY-SA-3.0 (creativecommons.org) or GFDL (gnu.org)], via Wikimedia Commons

And farther…

And farther...

By Andrew Z. Colvin (Own work) [CC-BY-SA-3.0 (creativecommons.org) or GFDL (gnu.org)], via Wikimedia Commons

Keep going…

Keep going...

By Andrew Z. Colvin (Own work) [CC-BY-SA-3.0 (creativecommons.org) or GFDL (gnu.org)], via Wikimedia Commons

Just a little bit farther…

Just a little bit farther...

By Andrew Z. Colvin (Own work) [CC-BY-SA-3.0 (creativecommons.org) or GFDL (gnu.org)], via Wikimedia Commons

Almost there…

Almost there...

By Andrew Z. Colvin (Own work) [CC-BY-SA-3.0 (creativecommons.org) or GFDL (gnu.org)], via Wikimedia Commons

And here it is. Here’s everything in the observable universe, and here’s your place in it. Just a tiny little ant in a giant jar.

And here it is. Here's everything in the observable universe, and here's your place in it. Just a tiny little ant in a giant jar.

By Andrew Z. Colvin (Own work) [CC-BY-SA-3.0 (creativecommons.org) or GFDL (gnu.org)], via Wikimedia Commons


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2014 Ozone Hole Update

The Antarctic ozone hole reached its annual peak size on Sept. 11, according to scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA). The size of this year’s hole was 24.1 million square kilometers (9.3 million square miles) — an area roughly the size of North America.

splash

This image shows ozone concentrations above Antarctica on Sept. 11, 2014. Image Credit: NASA. See also NASA’s Ozone Hole Watch website

The single-day maximum area was similar to that in 2013, which reached 24.0 million square kilometers (9.3 million square miles). The largest single-day ozone hole ever recorded by satellite was 29.9 million square kilometers (11.5 million square miles) on Sept. 9, 2000. Overall, the 2014 ozone hole is smaller than the large holes of the 1998–2006 period, and is comparable to 2010, 2012, and 2013.

With the increased atmospheric chlorine levels present since the 1980s, the Antarctic ozone hole forms and expands during the Southern Hemisphere spring (August and September). The ozone layer helps shield life on Earth from potentially harmful ultraviolet radiation that can cause skin cancer and damage plants.

The Montreal Protocol agreement beginning in 1987 regulated ozone depleting substances, such as chlorine-containing chlorofluorocarbons and bromine-containing halons. The 2014 level of these substances over Antarctica has declined about 9 percent below the record maximum in 2000.

“Year-to-year weather variability significantly impacts Antarctica ozone because warmer stratospheric temperatures can reduce ozone depletion,” said Paul A. Newman, chief scientist for atmospheres at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The ozone hole area is smaller than what we saw in the late-1990s and early 2000s, and we know that chlorine levels are decreasing. However, we are still uncertain about whether a long-term Antarctic stratospheric temperature warming might be reducing this ozone depletion.”

image

The graphs above show the progress of the 2014 ozone hole. The gray shading indicates the highest and lowest values measured since 1979. The red numbers are the maximum or minimum observed values. The stratospheric temperature and the amount of sunlight reaching the south polar region control the depth and size of the Antarctic ozone hole. [more]

Scientists are working to determine if the ozone hole trend over the last decade is a result of temperature increases or chorine declines. An increase of stratospheric temperature over Antarctica would decrease the ozone hole’s area. Satellite and ground-based measurements show that chlorine levels are declining, but stratospheric temperature analyses in that region are less reliable for determining long-term trends.

Scientists also found that the minimum thickness of ozone layer this year was recorded at 114 Dobson units on Sept. 30, compared to 250-350 Dobson units during the 1960s. Over the last 50 years satellite and ground-based records over Antarctica show ozone column amounts ranging from 100 to 400 Dobson units, which translates to about 1 millimeter (1/25 inch) to 5 millimeters (1/6 inch) of ozone in a layer if all of the ozone were brought down to the surface.

The ozone data come from the Dutch-Finnish Ozone Monitoring Instrument on NASA’s Aura satellite and the Ozone Monitoring and Profiler Suite instrument on the NASA-NOAA Suomi National Polar-orbiting Partnership satellite. NOAA measurements at South Pole station monitor the ozone layer above that location by means of Dobson spectrophotometer and regular ozone-sonde balloon launches that record the thickness of the ozone layer and its vertical distribution. Chlorine amounts are estimated using NOAA and NASA ground measurements and observations from the Microwave Limb Sounder aboard NASA’s Aura satellite.

NASA and NOAA are mandated under the Clean Air Act to monitor ozone-depleting gases and stratospheric depletion of ozone. Scientists from NASA and NOAA have been monitoring the ozone layer and the concentrations of ozone-depleting substances and their breakdown products from the ground and with a variety of instruments on satellites and balloons since the 1970s. These observations allow us to provide a continuous long-term record to track the long-term and year-to-year evolution of ozone amounts.


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Nature’s Anti-Aging Secret Ecologists are finding animals and plants that defy aging.

forever-young

A dozen years ago, Daniel Doak began crawling around the Alaskan tundra carrying a container of colorful party toothpicks. He was there on the chilly North Slope at the top of the continent to study moss campion, a low, flat plant that explodes with pink flowers in early summer.

Moss campion seedlings are “the size of the head of a pushpin,” Doak says, and 20 years can pass before they grow much bigger. Nonetheless, Doak, an ecologist at the University of Colorado, dutifully identified, mapped and measured the plants, using the toothpicks to mark the location of the smallest ones.

moss-campion

Moss campion in bloom.

Tracy Feldman

Every summer he returns, and after all those years of strained eyes and bruised knees, he now has data on 2,500 plants in the Arctic and thousands more at sites across the globe, from the Rocky Mountains to the Pyrenees. (Moss campion grows across a wide swath of the world’s high latitudes and elevations.) That information led Doak and his collaborator, Duke University ecologist William Morris, to a surprising find: The plants live for centuries. And that insight is helping to shape an emerging field: the science of how nature ages.

Initially, Doak simply wanted to understand how organisms respond to harsh environmental conditions, such as the frigid temperatures of an Alaskan winter. “How does a species make a living,” he wondered, “in a place where it’s tough to get established and tough to live?” So Doak and Morris recorded basic demographic data, measuring things like how fast the plants grow — and how long they live. “We do the equivalent of what the Census Bureau does,” says Doak. “We ask, ‘Are you alive? How big are you? How many children do you have?’ ”

By tracking the plants year after year, Doak has shown that moss campion follows a biological strategy known as negative senescence. Senescence is the scientific term for what we commonly think of as aging. All aging really signifies is time lived. To us, there’s no separating the passage of time from the process of decline. We see it in ourselves: gray hair, bad knees, flagging energy. But in negative senescence, the risk of death decreases as an organism grows older.

For years, biologists believed this strategy was largely impossible. Everything that survives for long enough, they thought, will eventually enter a deteriorating slide toward death. A combination of long-term data sets and new computational tools is painting a different picture: plants and animals that stay healthy, and even reproduce, for far longer than anyone would have predicted. Death may still be their ultimate fate, but it doesn’t represent the end point of decline. It arrives via catastrophe, or a whim of nature, or as a result of human-caused changes to the environment.

Doak and other scientists examining how various species age have discovered that in some cases, they simply don’t. Evolution may sometimes favor organisms that follow a different path. “Clearly there are ways for natural selection to dramatically change how senescence happens,” Doak says. “It doesn’t seem that hard to defeat senescence.”

studying-campion

Duke scientists William Morris (left) and Patrick Corcoran study tiny moss campion plants in Alaska’s Wrangell Mountains.

Rachel Mallon

Questions of Life and Death

Doak’s conclusion would have seemed heretical just a few years ago.

Why living things age is one of biology’s most vexing questions. For the past several decades, biologists have clung to a trio of theories, all of which hold that senescence is inescapable. One theory holds that organisms age because of built-up genetic mutations that aren’t weeded out by natural selection — a disease, say, that hits after your reproductive prime. Another maintains that aging occurs because some traits that make you better at reproducing may also cue your demise. And according to a third theory, as organisms age they deteriorate and must spend more energy to repair cell damage — to the detriment of other essential physical functions.

toothpicks

Toothpicks mark the smallest seedlings.

Daniel Doak

For years scientists have quibbled over which theory proved the best, but few doubted that, among the three, they explained the evolution of aging.

Now a new branch of the science of aging has sprouted, from a part of the world that, oddly, was excluded before: nature. And its early results suggest that those long-standing theories only tell part of the story. Until as recently as a decade ago, the mostly lab-based scientists who studied aging assumed that senescence wasn’t visible in nature. You wouldn’t see it in the wild, they believed, because the cruel realities of nature simply don’t allow anything to live long enough to decline. But years of data from long-term studies by Doak and other scientists examining plants, birds, mammals and fungi in the field are showing the flaws in these assumptions.

“There’s dogma in the literature — which is more oriented toward the cell biology of aging — that wild animals don’t actually senesce,” says Daniel Nussey, an evolutionary ecologist at the University of Edinburgh who studies aging in Soay sheep on a remote Scottish island. “That is absolutely wrong. This process can be seen, and it is shaped by evolution.”

In fact, signs of nature aging are all around us. Nussey’s wild sheep shed several pounds the year before they die; alpine ibex older than 8 or 9 can’t tolerate harsh weather; some plants lose their ability to survive drought. Elderly albatross seek out food in different areas than they did in their youth. Why organisms age differently — the comparative biology of aging — is a growing fascination for scientists. “We’re trying to understand what it is that drives variation in this process,” Nussey says.

That variation, it turns out, includes species that simply don’t follow the established rules. Back in 2004, a team of scientists looked at the emerging evidence from ecology and proposed that aging isn’t inevitable at all. In a controversial paper published in the journal Theoretical Population Biology, they wrote that “some, and perhaps many, species show negative senescence” — a situation in which death rates actually fall as the years pass.

bristlecone-pines

Bristlecone pines, like this one in California’s White Mountains, can live for thousands of years.

Neil Lucas/Nature Picture Library

Live Slow, Die Old

Since then, evidence of negative senescence has been stacking up.

In the case of moss campion, the plant has evolved a strategy of slow, deliberate growth. Doak believes it spends much of its early energy building an extremely long tap root that helps ensure water and nutrients later on, but slows the plant’s above-ground growth in the meantime. In the moss campion’s tundra home, “it’s very hard to get established,” says Doak. But once it is, its chances of surviving and eventually reproducing are high. There’s not much that will kill moss campion. The plant is so flat and low to the ground, and its leaves so tiny (less than half an inch long), that caribou and Dall sheep have a hard time eating it.

To Doak, it makes sense that natural selection would, in this case, act against aging. “Random catastrophes aren’t going to kill you, and it’s worth your while to put your investment in yourself rather than just in putting out offspring,” he says. Rather than “live fast, die young,” the campion strategy is more “live slow, die old.” Really, really old.

With some organisms, really old can mean millennia. High in the White Mountains near the California-Nevada border live some of the oldest trees in the world. Their trunks thick and gnarled, their oldest needles, born when JFK was president, still hanging on, these bristlecone pines are nearly 5,000 years old. Living five millennia is quite a feat, but what’s even more surprising is that these trees show no sign of decline. They are more likely to survive environmental stress than their younger cohorts, and they continue to reproduce at a steady rate. Their measured growth allows them to build extra-durable wood that resists rot, drought and lightning. In other words, in this case, natural selection appears to favor avoiding senescence entirely.

But plants are hardly the only organisms defying the aging process. Studies of turtles and lizards have also turned up negative senescence. One long-term study of three-toed box turtles in Missouri found that the animals were still reproducing well into their 70s.

In the mammal world, naked mole rats are the longest-living rodents. They can reach nearly 30 years of age in captivity. Scientists have found that breeding females “show no decline in fertility even well into their third decade of life,” according to a 2008 study published in the Journal of Comparative Physiology B. That makes sense, says Doak: “They live underground, in a resource-poor environment. They live cooperatively, meaning that your only chance to reproduce is after you’ve lived for a while and moved up the social strata.” Natural selection in this scenario favors individuals that live longer.

A New Threat

Doak’s moss campion research has lately turned up more than just evidence for negative senescence. He’s also found signs that global warming may be exerting a tangible influence on death’s odds. Close monitoring of the Alaskan moss campion plants over the years reveals that what’s most likely to kill the plants today is climate. “In winters when it’s quite cold but there are warm periods, the plants lose the blanket of snow that covers them,” Doak explains. They come down with the equivalent of freezer burn; ultimately, they die from being freeze-dried. “We’ve been seeing more and more of that over the course of our study,” he says.

While global warming represents a hurdle for the plants, Doak himself faces a more existential challenge. “It’s very difficult,” he admits, “to show that senescence doesn’t ever occur.” To prove conclusively that something doesn’t age would itself require human immortality. And, unfortunately, negative senescence in humans remains elusive.