Tag Archives: Nature

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.

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.

Sleeping Brains Understand Words

Have you ever heard someone describe a task as being so easy that they ‘could do it in their sleep’? A fascinating new study from a team of French neuroscientists shows that this statement may be literally true, far more often than you’d think: Inducing Task-Relevant Responses to Speech in the Sleeping Brain


Sid Kouider and colleagues’ elegant experiment went as follows. Volunteers were asked to perform a word categorization task: spoken words were played to them and they had to press a button with their left hand (say) if the word was a kind of animal, or press a button with their right hand if it was an object.

So far, so simple – but the kicker was that participants were allowed to fall asleep during the task. The experiment took place in a quiet, dark room to help them nod off. Once a volunteer was soundly asleep, the task continued – more animal and object words were played to them while they slept.

The key question was: did the volunteers’ brains continue to perform the task while they were asleep? This might seem like a hard hypothesis to test – how can a brain ‘perform’ a button pressing task, without pressing any buttons, and how would we know even if it? Well, the participants were wired up to an EEG system to record brain electrical activity, before the experiment began. Based on the EEG data from the awake phase of the experiment, Kouider et al were able to record the different neural activations that accompanied pressing a button with either the left or the right hand. (These activations happen on opposite sides of the brain, fittingly.)

button_press_kouider

The authors then examined whether these same ‘button pressing’ patterns occurred in response to the stimuli presented during sleep – and amazingly, they did, in most cases. The truly remarkable result was that the sleeping brains ‘produced’ the correct responses to the stimuli. If an animal word was played, the brain’s activity was usually consistent with it making a (say) left hand button press.

So this is pretty amazing and suggests that the brain can perform a high-level language task, involving understanding the meaning of words, while asleep. There are some questions, of course. As Kouider et al say:

First, one might question whether participants in our study were truly asleep… in order to be fully confident that the trials that we included in our analysis genuinely reflect a state of sleep, microarousals and arousals (associated with button presses or not) were detected and trials in the direct vicinity of these events were discarded.

Finally, this paper made me think of the Chinese Room – a philosophical thought-experiment in which a man with an elaborate instruction book is able to respond, in Chinese, to questions posed in Chinese, even though he doesn’t know the language and has no (conscious) understanding of what he’s saying. Is a sleeping brain rather like that man? A sleeping brain has no conscious experience of the outside world, so far as we know. Yet somehow it knows how to respond to words…!

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.

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.”

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

Seals Blood Contains As Much Carbon Monoxide As A Heavy Smokers’

Elephant seals are some of the world’s most elite divers, plunging to depths of 800 meters and holding their breaths underwater for nearly half an hour at a time. They also have as much carbon monoxide in their blood as a two-pack-a-day smoker, a new study shows. The poison even appears to offer a protective effect for them. 
 
Carbon monoxide (CO) is known as the “silent killer” because it’s a colorless, odorless gas that binds to hemoglobin, especially in the blood of smokers and firefighters. It clogs up the oxygen-carrying protein, prevents oxygen transport to tissues, and eventually causes light-headedness or even suffocation. Our bodies do naturally produce CO when heme-proteins are broken down; about 1 percent of the hemoglobin in non-smokers is bound by CO. Previous work has shown that low concentrations can be beneficial: reducing inflammatory responses and cell death caused by heart attacks and strokes. 
 
The northern elephant seal (Mirounga angustirostris) has the largest blood volumes of any mammals. To conserve oxygen for vital organs like the heart, brain, and lungs during long dives, their bodies can shut off blood flow to nonessential areas of their body, without damaging the tissues. “These animals are constantly holding their breath,” Michael Tift of Scripps Institution of Oceanography at University of California, San Diego, tells Nature. “But they don’t have any injuries.”
 
Tift and colleagues (pictured below) wanted to see how much CO elephant seals carry. So the team mildly sedated 24 elephant seals ranging from pups to the easily recognizable adult males at Año Nuevo State Park in California and collected blood samples. Then they used a blood gas analyzer to measure the proportion of hemoglobin incapacitated by CO — called carboxyhemoglobin (COHb) — relative to oxygen and carbon dioxide. 
 
The animals’ COHb levels were 10.4 percent of their total hemoglobin concentration. These are the values found in people who smoke up to 40 cigarettes a day, Tift says. And COHb levels increased as the animals aged. While high, their levels didn’t lead to carbon monoxide poisoning; the gas becomes deadly when it incapacitates more than 50 percent of hemoglobin stores, Tift explains to LiveScience.
 
So why that high? There’s only one way for an animal to clear CO from its body: Exhale it. Elephant seals probably accumulate so much COHb because they hold their breath for about 75 percent of their lives. “If they are at sea, they are constantly diving; if they are on land, they are going into sleep apneas [breath holds]. Since they are producing this stuff, they may be producing it at a similar rate to humans, but they may not be getting rid of it at the same rate,” Tift says. Alternatively, he suggests that the seals may simply produce more CO than other species because they break down heme-proteins faster, turning over more of the molecules.
 
While these COHb levels might reduce the seals’ dive limit, the constant presence of elevated CO in the blood may protect them against damaging inflammation incurred when the blood rushes back into tissues after their extreme breath-holds. 
 
In humans, blood flow is interrupted during organ transplants, strokes, and heart attacks; when blood suddenly flows back into the tissues, chemical reactions can lead to inflammation and cell death. These are called ischemia-reperfusion injuries, and they don’t seem to happen to seals. “These results are helping us find answers for the rates at which you can expose organs and tissues to this gas,” Tift says in a news release. “The elephant seal is giving us the big picture of which concentrations of carbon monoxide might be the most beneficial.” 
 
The work was presented at Experimental Biology 2014 in San Diego last month and published in the Journal of Experimental Biology last week. 

 

Caloric Restriction Increases Lifespan In Monkeys

A 25-year study published recently in Nature Communications has demonstrated that caloric restriction in rhesus monkeys bestowed numerous health benefits by reducing both mortality and age-associated diseases. These results contradict an earlier study which reported no differences in survival rates, but the scientists also believe they have an explanation for this.

Restricted calorie intake whilst maintaining a continued supply of essential nutrients has been demonstrated previously to increase the longevity of several different organisms, from unicellular yeast to mice and fruit flies. Alongside a longer lifespan, this caloric restriction (CR) also delayed the onset of multiple age-related diseases in rodents. In order to gain more translatable information which could infer the effects of CR in humans, researchers turned to monkeys. This is because non-human primates display physiological, anatomical and behavioral similarities to humans. Rhesus macaques, which were used in this study, also display similar aging characteristics to humans such as greying of the hair and loss of muscle tone. Certain diseases which are associated with increased age in humans such as diabetes and bone loss also become more prevalent with aging in these animals. 

Researchers from the University of Wisconsin, Madison (UWM) used 76 rhesus monkeys for the study which were divided into two groups. In the control group the monkeys were fed ad libitum and received as much food as they wanted, whereas the other (CR) group received a diet containing 30% less calories than what they had been previously eating. The monkeys within the control group had a 2.9-fold increased risk of disease and a 3-fold increased risk of death when compared with the CR group. This is in stark contrast to a previous influential study carried out by the National Institute on Aging (NIA). They also carried out a long-term study on 120 monkeys and found no significant differences between the CR group and the control group. 

The scientists from UWM pondered why this could be, and have offered some possible explanations. According to Ricki Colman from UWM, her group began working with adult monkeys which meant that they already knew how much food the monkeys wanted to eat; they therefore took this amount as the normal calorie intake and reduced the calories by 30% from this. The NIA, however, based their feeding amounts on a standardized chart issued by the National Academy of Science. The scientists from UWM concluded that this resulted in the monkeys in the control group also receiving a reduction in calories, which could explain why no differences were seen. Colman also found that the control monkeys at NIA weighed less at all times during the study when compared to the monkeys used in the UWM study. 

Although encouraging and informative, these data should be interpreted with care. One of the authors of the study, Rozalyn Anderson, pointed out that it is important to realize that the results should not be used as a lifestyle recommendation; few people can cope with a constant 30% reduction in calories. “We are not studying it so people can go out and do it, but to delve into the underlying causes of age-related disease susceptibility,” she adds. According to Anderson, in the species that have been investigated so far CR causes metabolism to be reprogrammed and affects the ability of the organism to respond to environmental changes. 

Although similar data are available from human studies, they are more clinically restricted than monkey studies. Rodent studies previously carried out are also limited in what they can inform us of what is happening in humans. The authors propose that the benefits of CR on aging are conserved among primates, and suggest that the advances from this study will translate directly to human aging and health. 

 

Obesity linked to our ability to digest carbohydrates

“I’m off the carbs” is a familiar refrain among dieters. But could this approach to losing weight be more beneficial to some people than others?

That’s the implication of research suggesting that obesity may be linked to how our bodies digest the starch found in carbohydrate-rich foods like bread, rice and potatoes.

When we eat, an enzyme in saliva called salivary amylase kick-starts digestion by breaking down some of the starch found in carbohydrates into sugars. This enzyme is produced by the gene AMY1.

It’s an unusual gene, in that people can have multiple copies of it, unlike most genes where there are just two. The more copies you have, the more enzyme you produce. One theory is that humans evolved to carry more copies of the gene as our diets shifted towards carbohydrate-rich foods.

Gene shortlist

Mario Falchi at Imperial College London and colleagues compared the genome sequences of a group of siblings where one was overweight, the other lean, and drew up a shortlist of genes which might help explain the difference. AMY1 topped the list.

Next, they studied a separate group of 5000 people from France and the UK and found that people with fewer than four copies of the gene were around eight times more likely to be obese than those with more than nine copies of the gene.

This suggests that people who are good at breaking down starch into sugars are less likely to be obese. However, why this should be the case isn’t clear from this study as it doesn’t take into account the amylase produced by the pancreas, says Falchi.

“It is possible that the effect of the salivary amylase genes isn’t directly influencing the digestion of carbs and how much energy we get from them,” he says. “It could be through more complex mechanisms such as influencing signalling pathways, or changing the gut microbiota.”

Further studies to pull apart the mechanism are already underway.

Journal reference: Nature Genetics, DOI: 10.1038/ng.2939

Monkey Mind Control

Monkey Mind Control

 

A mind-boggling new study published this week in Nature Communications describes how researchers have found a way for one monkey to control the movements of another with its mind. Using two rhesus macaques, scientists implanted a chip into the brain of the “master” monkey that could convert its brain activity and send electrical impulses into the spine of a sedated primate, The Scientist reports. In one experiment, the master macaque was able to move a cursor by controlling a joystick in the hand of the sedated primate. The researchers believe the findings hold hope for paralyzed humans.