The biomass lost via the extinctions of large mammals such as mammoths and giant ground sloths during the last 50,000 years has largely been replaced by that of one species, Homo sapiens. The unprecedented success of humans is in large part possible only because people take advantage of fossil fuels, a new study suggests. Louis J. Sheehan.

About half of the mammalian megafauna species — loosely defined as those tipping the scales at 44 kilograms or more — have died out in the past 50,000 years, says Anthony D. Barnosky, a paleoecologist at the University of California, Berkeley. That leaves only about 180 non-human mammalian species of that size on Earth today, he reports in the Aug. 12 Proceedings of the National Academy of Sciences. http://louis-j-sheehan.biz

Between 50,000 and 7,000 years ago, a series of megafauna extinctions swept the planet. The timing of those die-offs, particularly those in Australia and some Caribbean islands suggests that the spread of humans played a large role in the losses. Indeed, Barnosky notes, most megafauna didn’t die out until human population worldwide began to rise steeply between 15,500 and 11,500 years ago.

Near the end of the last ice age, just as the largest wave of extinctions began, humans and other large mammals were consuming most of the fruits of the planet’s natural productivity, Barnosky contends. After the other large creatures died out, humans were poised to take advantage of the newly available natural resources, but a 1,300-year-long cold spell called the Younger Dryas period intervened, dropping natural productivity and constraining megafauna population growth.

When climate warmed at the end of the Younger Dryas, about 11,500 years ago, human numbers began to swell dramatically, Barnosky says. Nevertheless, megafauna biomass, including that of humans, didn’t reach pre-extinction levels until around 400 years ago, just before the beginning of the Industrial Revolution. http://louis-j-sheehan.biz Since then, human population has continued to grow at an ever-increasing rate, a trend directly attributable to human use of fossil fuels, Barnosky contends.

The energy stored in fossil fuels — essentially solar energy stored by plants long ago — is supplementing that falling as sunlight on Earth’s surface today. And, Barnosky notes, fossil fuels aren’t limitless: Some projections indicate that easily recovered oil will run out in around 50 years at the current rate of use, and coal will be used up in another 2,000 years or so. If humans haven’t discovered alternative sources of energy by then, populations of all megafauna — and particularly those of humans — will crash.

Homo sapiens is fabulously successful by ecological standards, Stanford biologists Paul Ehrlich and Robert Pringle comment in the Aug 12. Proceedings of the National Academy of Sciences. Not only does the human species boast an as-yet-unchecked population growth, it has spread to all corners of the globe and vanquished many of its predators, competitors and parasites, they note. Previous studies suggest that humans alone consume almost a quarter of the planet’s natural productivity, often at the expense of other species.

And biodiversity isn’t likely to improve in the near future, the researchers note. Today’s rate of species die-offs is likely thousands of times higher than long-term rates experienced during past geological ages. Not only that, they say, human dominance of many ecosystems will probably stifle the evolution of large creatures — ones that typically are highly mobile and require large habitats — for the foreseeable future. “The fate of biological diversity for the next 10 million years will almost certainly be determined during the next 50 to 100 years by the activities of a single species,” Homo sapiens, Ehrlich and Pringle propose. Louis J. Sheehan.

Louis J. Sheehan. A team of researchers is developing computer-generated, virtual reality technology to prepare 12-to-16-year-old Greek children, including those with special needs, for a terrifying event they're likely to encounter: an earthquake.http://louis-j-sheehaN.NET

The researchers created a computer model of a local school filled with virtual students. The model triggers sounds, rolling motions, and tumult associated with a major quake. Psychologist Ioannis Tarnanas of the Western Macedonia Research Center in Kozani, Greece, then recruited 50 children with Down syndrome and 90 children without that disorder to don headphones and scene-projecting goggles to experience a quake hitting the virtual school.

By chance, a real earthquake occurred a few months after the children had received the training. The researchers then assessed differences in coping and emotional security between children who had and hadn't been prepared by the virtual reality training.

Tarnanas found that the trained children outperformed their untrained counterparts in coping with a real quake, according to answers to questionnaires given each group. For instance, among children without Down syndrome, trained students were 45 percent better at following their teachers' quake-safety instructions. http://louis-j-sheehaN.NETChildren with Down syndrome showed nearly as big an improvement with training. In a separate measurement, 87 percent of the virtually trained children with Down syndrome were panicfree after the real quake versus just 20 percent of untrained students with the disorder.

Concludes Tarnanas, "We showed [that] virtual reality is useful for children, even those with special needs, in reducing natural [panic] about unexpected events."

Louis J. Sheehan. Fingerprints can tell a lot more about people — what they’ve touched, what they’ve eaten, what drugs they’ve taken — than just their identities. Now, a new analytic tool could make it easier to spot terrorists and to diagnose diseases from telltale chemical markers, but could also pose new privacy risks.http://louishjhsheehan.blogspot.com

The method, described in the Aug. 8 Science, can map a fingerprint based on the presence of virtually any water-soluble chemical. “It’s the difference between a black-and-white picture and a full-color picture,” says chemist Graham Cooks of Purdue University in West Lafayette, Ind.

Cooks and his colleagues singled out traces of chemicals, such as the high-power explosive RDX, cocaine and THC, marijuana’s main active ingredient.

The researchers used a technique called DESI, pioneered by him and his collaborators in 2004. In DESI, researchers spray microscopic droplets of water onto a sample. The first droplets that hit the sample form a film that dissolves chemicals on the sample’s surface. When additional droplets splash onto the liquid film, some droplets bounce back and are sucked into a tube.

There, the droplets are heated to isolate the chemicals, which usually break into smaller molecules. Finally, the device performs the traditional technique of mass spectrometry, which identifies molecules according to their molecular weight.

Researchers mapped the fingerprints by using the device to scan individual spots — each one-fifth of a millimeter wide — one at a time.

Mass spectrometers, Cooks says, are among the most sensitive and precise tools available to the chemist. “When they really need answers in CSI — they put things in the mass spec,” he adds.

But traditional mass spectrometry requires samples to be analyzed in a vacuum, while DESI can be used in the field and on any surface.

“DESI is extremely powerful and promising,” says Facundo Fernandez, a chemist at the Georgia Institute of Technology in Atlanta. “It gives a ton of information.”

Cooks says DESI could also be tested as a tool for medical diagnosis. In principle, fingerprints could contain chemicals, not found through blood or urine tests, that indicate the presence of a disease.

DESI is not the first technique that’s been used for finding chemicals in fingerprints. Recently, researchers have experimented with a technique that analyzes chemicals by scanning them with a laser.http://louishjhsheehan.blogspot.com

Also, last year, Sergei Kazarian of Imperial College London and his collaborators showed how they could do that by bouncing infrared rays off an object. The infrared method is faster, doesn’t damage the sample and doesn’t require knowing in advance where a fingerprint is likely to be, Kazarian points out.

Cooks says the effectiveness of the two techniques should be compared in blind tests. “This is where we need to have a shoot-off at the O.K. Corral.”

Meanwhile, if such chemical analytic tools become available as consumer gadgets, anyone — employers, spouses, school principals — could potentially discover details just by pointing their DESI pen at fingerprints on somebody’s paper cup. “This is a major concern,” Cooks says. “The implications for privacy are written all over this.” http://louisjjjsheehan.blogspot.com

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Louis J. Sheehan. Southeastern Asian forests harbor a small-bodied line of apes, known as gibbons, that sing like rainforest Pavarottis. These animals' full-throated refrains reverberate through dense vegetation.

A research team has now gone behind the music and gleaned the first evidence that singing gibbons rearrange notes to communicate with their comrades. This simple system, or syntax, for recombining sounds to convey messages represents a step toward human language that had not previously been demonstrated in apes, says psychologist Esther Clarke of the University of St. Andrews in Scotland. http://ljsheehan.blogspot.com

Researchers have traditionally held that syntax arose only as the vocabulary of prehistoric people grew large and unwieldy. "We're finding the opposite in gibbons," says psychologist Klaus Zuberbühler, also of the University of St. Andrews. "One way of escaping the constraints of their limited vocal abilities is to combine signals into more-complex sequences, which carry meaning."

Gibbons evolved complex vocal skills as a tool for finding long-term mates in a competitive social scene, the scientists theorize. In the December 2006 PLoS ONE, a new online journal, Clarke, Zuberbühler, and a colleague outline basic rules for gibbon songs stimulated by a predator's presence versus those crooned with a mate.

From April 2004 to August 2005, the researchers studied 13 groups of white-handed gibbons living in Thailand's Khao Yai National Park. Each group consisted of two to six members—usually an adult pair, its offspring, and occasionally another adult male.

Clarke elicited predator songs by placing realistic models of threatening animals in trees where an entire group of gibbons could see them. Models included a fake fur–wrapped sack representing a leopard and a painted, papier-mâché, crested serpent eagle covered in feathers.

The team recorded predator-induced songs, which began with series of soft "hoo" notes and included many instances of another note. Each predator tune lasted roughly 30 minutes. http://ljsheehan.blogspot.com

Pairs of adult males and females that mate for life perform duets, often adjusting the tunes over time. In the new experiment, adult pairs of each group spontaneously produced duets that were captured by the audio recordings. http://ljsheehan.blogspot.com These songs lacked introductory "hoo" notes and the repeated extra note of the predator songs, and duets lasted only 10 minutes.

Gibbons within earshot of singing comrades discriminated between duets and predator songs. Nearby females emitted a characteristic brief call after hearing any song, but they delayed this response for 2 minutes or more following predator tunes. All members of neighboring groups responded to predator-induced crooning by loudly repeating the sequence of notes.

Although a substantial gap separates human language from ape communication, the new study shows that "in gibbons, the difference in degree of vocal complexity and sophistication is not as large as some have been tempted to think," remarks biological anthropologist Barbara J. King of the College of William and Mary in Williamsburg, Va.

Biologist Dorothy Cheney of the University of Pennsylvania in Philadelphia recommends that recordings of the two song types be played to gibbons in the same setting. http://ljsheehan.blogspot.com She adds that syntax in gibbon songs falls short of that in language, which uses words to serve specific functions in sentences as well as to refer to features of the world.

Louis J Sheehan. Short-term exposure to high concentrations of tiny airborne particles does not hurt heart function, according to new research.http://Louis-J-sheehan.info

In earlier studies, people’s blood pressure spiked after even brief exposures to concentrated particulate air pollution. Taken together, the new work and previous studies suggest that the size and chemical makeup of the particles are more important indicators of health risk than the overall concentration in the air.

Scottish scientists tested 12 middle-aged men who had previously experienced a heart attack or undergone heart surgery and 12 age-matched, healthy men. Participants from each group were randomly assigned to sit for two hours in a chamber and breathe either filtered ambient air from Edinburgh or similar air with much higher concentrations of particles.

The team then measured heart rate, blood pressure and markers of inflammation in all the men. Those inhaling high concentrations of fine particles had similar markers of heart function as those breathing filtered air, the team reported in the June Environmental Health Perspectives.

Past studies have shown that similar exposure to high concentrations of particles from diesel exhaust raises blood pressure and constricts blood vessels, says Robert Brook, a cardiologist at the University of Michigan in Ann Arbor who was not involved in the study. “This suggests that particulate matter source, composition or chemistry may play an important role in determining the cardiovascular health implications of exposure,” he says.

Edinburgh sits on the edge of the North Sea, and strong winds carry most pollutants away from the city. So sea salt formed the bulk of airborne particles in this study, says Nicholas Mills a physician at the Edinburgh University Center for Cardiovascular Science and the lead author of the new paper. And sea salt may be more innocuous than particulates formed by combustion, such as diesel particles, he says.

One factor may be particle size and shape, Mills notes. Diesel specks measure 20 to 100 nanometers in diameter. In contrast, particles in the study were often 20 times larger. Tiny specks can penetrate deeper into the lungs and lead to higher levels of toxins in the blood.

The chemical makeup of carbon-rich fuel exhaust may also be inherently more toxic for humans, Mills say. While the study was well done, it only a tested a small number of people, Brook says. It also tested people in only one urban setting. Future work should be conducted in two separate cities, he says. http://Louis-J-sheehan.info

Currently air pollution is regulated only by the absolute concentration of particles suspended in the air, Mills says. Air testing might more effectively protect public health if it also tracked particles by size — specifically the amount of tiny, diesel-sized particles in the air, he says.