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Sperm whales’ clicks suggest the animals have culture The whales appear to learn sounds to socialize, similar to the way humans learn language

sperm whale

Sperm whales love to chitchat. They talk to each other in clicks. Now, scientists say, those clicks hold hints that the whales have culture.

Culture is a way of life passed on from generation to generation through learning. “There’s a lot of debate if culture is exclusive to humans or if you can find it in animals, too,” says Maurício Cantor. He is a biologist at Canada’s Dalhousie University in Halifax, Nova Scotia. Earlier research had suggested that dolphins, primates, birds and a few other wild animals have culture. Sperm whales should be added to that list, Cantor and his colleagues now argue in the September 8 Nature Communications.Sperm whales can make some of the deepest dives of all the animals in the sea. They can plunge up to 2,250 meters (7,380 feet) below the ocean’s surface. And they can stay underwater for nearly 90 minutes. When diving, the whales send out loud clicks and listen for the echoes that bounce back after the clicks hit something close by. This is calledecholocation. It’s the animal equivalent of sonar, and the whales use it to hunt — mainly for large squid. But when the whales are not hunting, they use those clicks to chat with each other.

Females and their calves do most of the talking. Tens of thousands of them hang out in the warm waters of the South Pacific Ocean. They usually swim in small units of 12 or so moms, grandmas, aunts and friends. These gals all work together to raise their pod’s babies.

These units are part of larger groups of 30 to 300 whales, which belong to even larger communities, called clans. Individuals in each clan talk to each other using distinct patterns of clicks. These varying patterns are similar to dialects in human speech. A dialect is a regional pattern in speech. People in Boston, Mass., and Dallas, Tex., both speak English, for example. Yet they may use words differently or give them a different pronunciation. Those differences reflect their regional dialects.

Cantor and his colleagues wanted to know how the whales got their distinct dialects. The researchers followed groups of whales around the Galápagos Islands, off South America. Along the way, they recorded the whales’ identities and behaviors. The scientists logged the whales’ sounds and tracked with which other groups these sperm whales interacted.

Back in their lab, the scientists loaded all of these data into a computer. Then they programmed it to test different ways the whale dialects could have developed over thousands of generations. Perhaps the dialects developed by chance. Or there might have been some innate bits of sound passed from mom to baby through DNA. The computer program ruled out both of those scenarios. Instead, the analysis showed that the whales had to have learned their distinct dialects from the other whales around them.Scientists refer to this as social learning.

“Social learning is the foundation of culture,” Cantor says. Because sperm whales learn their dialects from their extended family, there are cultural differences between clans. The clans actually exist because of those cultural differences, he says.

Luke Rendell is a biologist at the University of St. Andrews in Scotland. He was not involved in the study. He points out that the new finding is based on a computer model of how the sperm whale dialects came to be. A model, though, can only simulate the real world. It is not a direct observation of what actually occurred. “Like all models, it is wrong, but it is also useful,” Rendell says.

The model suggests whales have a bias for the sounds of their own clan members, which shapes their society, Rendell notes. This kind of conformity, or sticking with individuals who behave the same, is thought to underpin a lot of human culture. In non-humans, however, it is considered rare. Finding hints that it exists in sperm-whale clans “really starts to lift the lid on cultural processes in non-human societies,” he says.

Cantor notes that the scientists are not suggesting that the whales’ sounds or culture are as complex or diverse as human cultures are. But, he says, “Whale culture, like human culture, seems to be very important for the whales’ social structure.”

Power Words

(for more about Power Words, click here)

bias   The tendency to hold a particular perspective or preference that favors some thing, some group or some choice. Scientists often “blind” subjects to the details of a test so that their biases will not affect the result.

biology  The study of living things. The scientists who study them are known as biologists.

clan    A large family or group of families that have much in common, both genetically and culturally.

computer model A program that runs on a computer that creates a model, or simulation, of a real-world feature, phenomenon or event.

culture  (in social science) The sum total of typical behaviors and social practices of a related group of people (such as a tribe or nation). Their culture includes their beliefs, values, and the symbols that they accept and or use. It’s passed on from generation to generation through learning. Once thought to be exclusive to humans, scientists have recognized signs of culture in several other animal species, such as dolphins and primates.

dialect  A form of language or pattern of communication that is distinct to a specific place or a social group.

DNA  (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

dolphins  A highly intelligent group of marine mammals that belong to the toothed-whale family. Members of this group include orcas (killer whales), pilot whales and bottlenose dolphins.

echolocation  (in animals) A behavior in which animals emit calls and then listen to the echoes that bounce back off of solid things in the environment. This behavior can be used to navigate and to find food or mates. It is the biological analog of the sonar used by submarines.

generation  A group of individuals born about the same time or that are regarded as a single group. Your parents belong to one generation of your family, for example, and your grandparents to another. Similarly, you and everyone within a few years of your age across the planet -are referred to as belonging to a particular generation of humans.

innate  Something such as a behavior, attitude or response that is natural, or inborn, and doesn’t have to be learned.

model A simulation of a real-world event (usually using a computer) that has been developed to predict one or more likely outcomes.

pod    (in zoology) The name given to a group of toothed whales that travel together, most of them throughout their life, as a group.

primate  The order of mammals that includes humans, apes, monkeys and related animals (such as tarsiers, the Daubentonia and other lemurs).

programming  (in computing) To use a computer language to write or revise a set of instructions that makes a computer do something. The set of instructions that does this is known as a computer program.

scenario   A possible (or likely) sequence of events and how they might play out.

simulate  (in computing) To try and imitate the conditions, functions or appearance of something. Computer programs that do this are referred to as simulations.

social learning  A type of learning in which individuals observe the behavior of others and modify their own behavior based on what they see.

social network  Communities of people (or animals) that are interrelated owing to the way they relate to each other.

sonar  A system for the detection of objects and for measuring the depth of water. It works by emitting sound pulses and measuring how long it takes the echoes to return.

sperm whale  A species of enormous whale with small eyes and a small jaw in a squarish head that takes up 40 percent of its body. Their bodies can span 13 to 18 meters (43 to 60 feet), with adult males being at the bigger end of that range. These are the deepest diving of marine mammals, reaching depths of 1,000 meters (3,280 feet) or more. They can stay below the water for up to an hour at a time in search of food, mostly giant squids.

zoology  The study of animals and their habitats. Scientists who undertake this work are known aszoologists.

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Scientists have developed an eye drop that can dissolve cataracts

Researchers in the US have developed a new drug that can be delivered directly into the eye via an eye dropper to shrink down and dissolve cataracts – the leading cause of blindness in humans.

While the effects have yet to be tested on humans, the team from the University of California, San Diego hopes to replicate the findings in clinical trials and offer an alternative to the only treatment that’s currently available to cataract patients – painful and often prohibitively expensive surgery.

Researchers in the US have developed a new drug that can be delivered directly into the eye via an eye dropper to shrink down and dissolve cataracts – the leading cause of blindness in humans.

While the effects have yet to be tested on humans, the team from the University of California, San Diego hopes to replicate the findings in clinical trials and offer an alternative to the only treatment that’s currently available to cataract patients – painful and often prohibitively expensive surgery.

Affecting tens of millions of people worldwide, cataracts cause the lens of the eye to become progressively cloudy, and when left untreated, can lead to total blindness. This occurs when the structure of the crystallin proteins that make up the lens in our eyes deteriorates, causing the damaged or disorganised proteins to clump and form a milky blue or brown layer. While cataracts cannot spread from one eye to the other, they can occur independently in both eyes.

Scientists aren’t entirely sure what cases cataracts, but most cases are related to age, with the US National Eye Institute reporting that by the age of 80, more than half of all Americans either have a cataract, or have had cataract surgery. While unpleasant, the surgical procedure to remove a cataract is very simple and safe, but many communities in developing countries and regional areas do not have access to the money or facilities to perform it, which means blindness is inevitable for the vast majority of patients.

According to the Fred Hollows Foundation, an estimated 32.4 million people around the world today are blind, and 90 percent of them live in developing countries. More than half of these cases were caused by cataracts, which means having an eye drop as an alternative to surgery would make an incredible difference.

The new drug is based on a naturally-occurring steroid called lanosterol. The idea to test the effectiveness of lanosterol on cataracts came to the researchers when they became aware of two children in China who had inherited a congenital form of cataract, which had never affected their parents. The researchers discovered that these siblings shared a mutation that stopped the production of lanosterol, which their parents lacked.

So if the parents were producing lanosterol and didn’t get cataracts, but their children weren’t producing lanosterol and did get cataracts, the researchers proposed that the steroid might halt the defective crystallin proteins from clumping together and forming cataracts in the non-congenital form of the disease.

They tested their lanosterol-based eye drops in three types of experiments. They worked with human lens in the lab and saw a decrease in cataract size. They then tested the effects on rabbits, and according to Hanae Armitage at Science Mag, after six days, all but two of their 13 patients had gone from having severe cataracts to mild cataracts or no cataracts at all. Finally, they tested the eye drops on dogs with naturally occurring cataracts. Just like the human lens in the lab and the rabbits, the dogs responded positively to the drug, with severe cataracts shrinking away to nothing, or almost nothing.

The results have been published in Nature.

“This is a really comprehensive and compelling paper – the strongest I’ve seen of its kind in a decade,” molecular biologist Jonathan King from the Massachusetts Institute of Technology (MIT) told Armitage. While not affiliated with this study, King has been involved in cataract research for the past 15 years. “They discovered the phenomena and then followed with all of the experiments that you should do – that’s as biologically relevant as you can get.”

The next step is for the researchers to figure out exactly how the lanosterol-based eye drops are eliciting this response from the cataract proteins, and to progress their research to human trials.


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Citizen Scientists Discover Yellow “Space Balls”

Citizen scientists scanning images from NASA’s Spitzer Space Telescope, an orbiting infra-red observatory, recently stumbled upon a new class of curiosities that had gone largely unrecognized before: yellow balls.

“The volunteers started chatting about the yellow balls they kept seeing in the images of our galaxy, and this brought the features to our attention,” said Grace Wolf-Chase of the Adler Planetarium in Chicago.

splash

A new ScienceCast video examines “yellow balls” and their role in star formation. Play it

The Milky Way Project is one of many “citizen scientist” projects making up the Zooniverse website, which relies on crowdsourcing to help process scientific data.  For years, volunteers have been scanning Spitzer’s images of star-forming regions—places where clouds of gas and dust are collapsing to form clusters of young stars.  Professional astronomers don’t fully understand the process of star formation; much of the underlying physics remains a mystery. Citizen scientists have been helping by looking for clues.

Before the yellow balls popped up, volunteers had already noticed green bubbles with red centers, populating a landscape of swirling gas and dust. These bubbles are the result of massive newborn stars blowing out cavities in their surroundings. When the volunteers started reporting that they were finding objects in the shape of yellow balls, the Spitzer researchers took note.

Auroras Underfoot (signup)

The rounded features captured by the telescope, of course, are not actually yellow, red, or green—they just appear that way in the infrared, color-assigned images that the telescope sends to Earth. The false colors provide a way to humans to talk about infrared wavelengths of light their eyes cannot actually see.

“With prompting by the volunteers, we analyzed the yellow balls and figured out that they are a new way to detect the early stages of massive star formation,” said Charles Kerton of Iowa State University, Ames. “The simple question of ‘Hmm, what’s that?’ led us to this discovery.”

A thorough analysis by the team led to the conclusion that the yellow balls precede the green bubbles, representing a phase of star formation that takes place before the bubbles form.

“Basically, if you wind the clock backwards from the bubbles, you get the yellow balls,” said Kerton.

splash

An artist’s concept shows how “yellow balls” fit into the process of star formation.

Researchers think the green bubble rims are made largely of organic molecules called polycyclic aromatic hydrocarbons (PAHs). PAHs are abundant in the dense molecular clouds where stars coalesce. Blasts of radiation and winds from newborn stars push these PAHs into a spherical shells that look like green bubbles in Spitzer’s images. The red cores of the green bubbles are made of warm dust that has not yet been pushed away from the windy stars.

How do the yellow balls fit in?

“The yellow balls are a missing link,” says Wolf-Chase. They represent a transition “between very young embryonic stars buried in dense, dusty clouds and slightly older, newborn stars blowing the bubbles.”

Essentially, the yellow balls mark places where the PAHs (green) and the dust (red) have not yet separated. The superposition of green and red makes yellow.

So far, the volunteers have identified more than 900 of these compact, yellow features.  The multitude gives researchers plenty of chances to test their hypotheses and learn more about the way stars form.

Meanwhile, citizen scientists continue to scan Spitzer’s images for new finds. Green bubbles.  Red cores.  Yellow balls.  What’s next?  You could be the one who makes the next big discovery.  To get involved, go to zooniverse.org and click on “The Milky Way Project.”


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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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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.


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Rocks Made of Plastic Found on Hawaiian Beach

Left behind. A sample of plastiglomerate, collected on Kamilo Beach in Hawaii.

Plastic may be with us a lot longer than we thought. In addition to clogging up landfills and becoming trapped in Arctic ice, some of it is turning into stone. Scientists say a new type of rock cobbled together from plastic, volcanic rock, beach sand, seashells, and corals has begun forming on the shores of Hawaii. 

“The article is intriguing and fascinating,” says geophysicist Douglas Jerolmack of the University of Pennsylvania, who was not involved in the work. “If these things can be preserved, then they might be a nice marker around the world of when humans came to dominate the globe and leave behind their refuse in mass quantities.”

Geologist Patricia Corcoran of the University of Western Ontario in London, Canada, and Charles Moore, captain of the oceanographic research vessel Alguita, stumbled upon the new rocks on a beach on the Big Island of Hawaii. These stones, which they’ve dubbed “plastiglomerates,” most likely formed from melting plastic in fires lit by humans who were camping or fishing, the team reports this month in GSA Today. Although anywhere there is a heat source, such as forest fires or lava flows, and “abundant plastic debris,” Corcoran says, “there is the potential for the formation of plastiglomerate.” When the plastic melts, it cements rock fragments, sand, and shell debris together, or the plastic can flow into larger rocks and fill in cracks and bubbles to form a kind of junkyard Frankenstein.

Corcoran says some of the plastic is still recognizable as toothbrushes, forks, ropes, and just “anything you can think of.” Once the plastic has fused to denser materials, like rock and coral, it sinks to the sea floor, and the chances it will become buried and preserved in the geologic record increase.

Corcoran and her team canvassed Kamilo Beach on the Big Island for more of the rocks and found plastiglomerate in all 21 sites they surveyed. She says people have already found plastiglomerate on another Hawaiian island, and she expects there to be much more on coastlines across the world. Plastiglomerate is likely well distributed, it’s just never been noticed before now, she says.

Jerolmack agrees. “All around the world where there’s trash being openly burned in mass quantities, you can imagine there are even larger melted plastic deposits” where plastiglomerate could form.

The discovery adds to the debate about whether humanity’s heavy hand in natural processes warrants the formal declaration of a new epoch of Earth history, the Anthropocene, says paleontologist Jan Zalasiewicz of the University of Leicester in the United Kingdom, who was not involved in the study. Plastics in general are so pervasive that they’ve been documented in a number of surprising places, including ingested in wildlife and on the sea floor. The mass of plastic produced since 1950 is close to 6 billion metric tons, enough to bundle the entire planet in plastic wrap. Combine plastic’s abundance with its persistence in the environment, and there’s a good chance it’ll get into the fossil record, Zalasiewicz says. “Plastics, including plastiglomerates, would be one of the key markers by which people could recognize the beginning of the Anthropocene.”

How long the plastic will endure remains a matter of debate, however. Jerolmack says he doubts the material will stick around in the fossil record. After all, plastic melts, and rocks often pass through hellish depths and temperatures through tectonic processes and burial. Geologist Philip Gibbard of the University of Cambridge in the United Kingdom says he imagines that plastics might “revert back to a source of oil from whence they came, given the right conditions of burial.” But Zalasiewicz and Corcoran say that isn’t true for all the plastic. Some of the material can be preserved as a thin carbon film, much like the way fossil leaves are preserved. Zalasiewicz says that in some rare cases, in that etch of carbon “you may well be left the shape for a flattened plastic bottle.”


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We are killing species at 1000 times the natural rate

First the bad news. Humans are driving species to extinction at around 1000 times the natural rate, at the top of the range of an earlier estimate. We also don’t know how many species we can afford to lose.

Birds from Brazil: let get more threatened species in the red zone <i>(Image: Clinton Jenkinst)</i>

Now the good news. Armed with your smartphone, you can help conservationists save them.

Interactive map:: Where the threatened wild things are

The new estimate of the global rate of extinction comes from Stuart Pimm of Duke University in Durham, North Carolina, and colleagues. It updates a calculation Pimm’s team released in 1995, that human activities were driving species out of existence at 100 to 1000 times the background rate (Science, doi.org/fq2sfs).

It turns out that Pimm’s earlier calculations both underestimated the rate at which species are now disappearing, and overestimated the background rate over the past 10 to 20 million years.

Gone gone gone

The Red List assessments of endangered species, conducted by theInternational Union for Conservation of Nature (IUCN), are key to Pimm’s analysis. They have evolved from patchy lists of threatened species into comprehensive surveys of animal groups and regions.

“Twenty years ago we simply didn’t have the breadth of underlying data with 70,000 species assessments in hand,” says team member Thomas Brooks of the IUCN in Gland, Switzerland.

By studying animals’ DNA, biologists have also created family trees for many groups of animals, allowing them to calculate when new species emerged. On average, it seems each vertebrate species gives rise to a new species once every 10 million years.

It’s hard to measure the natural rate of extinction, but there is a workaround. Before we started destroying habitats, new species seem to have been appearing faster than old ones disappeared. That means the natural extinction rate cannot be higher than the rate at which they were forming, says Pimm.

For the most part, the higher estimate of the modern extinction rate is not caused by any acceleration in extinctions since 1995. One exception is an increase in threats to amphibians, partly due to the global spread of the killer chytrid fungus.

 

Save everything

The big unknown is what the high current extinction rate means for the health of entire ecosystems. Some researchers have suggested “sustainable” targets for species’ loss, but there’s still no scientific way to predict at what point cumulative extinctions cause an ecosystem to collapse. “People who say that are pulling numbers out of the air,” says Pimm.

Still, it seems unlikely that extinctions running at 1000 times the background rate can be sustained for long. “You can be sure that there will be a price to be paid,” says Brooks.

Pimm’s team has also compiled detailed global maps of biodiversity, showing the numbers of threatened species and total species richness in a global grid consisting of squares 10 kilometres across.

Such maps can help conservationists decide what to do.

For instance, Pimm and his colleague Clinton Jenkins of the Institute for Ecological Research in Nazaré Paulista, Brazil, noticed high numbers of threatened species on Brazil’s Atlantic coast. Local forests were being cleared for cattle ranching. So they are working with a Brazilian group, the Golden Lion Tamarin Association, to buy land and reconnect isolated forest fragments.

But conservationists need more data, and you can help, through projects likeiNaturalist. Users share photos of the creatures they see via iPhone andAndroid apps, and experts identify them. “Right now, someone is posting an observation about every 30 seconds,” says co-director Scott Loarie of the California Academy of Sciences in San Francisco.

Interactive map: Where the threatened wild things are

Journal reference: Science, DOI: 10.1126/science.1246752