Archive for December, 2010

Did Early Humans Migrate Across a Watery, Green Sahara?

By Jennifer Welsh | December 30, 2010 9:02 am

The “cradle of humanity” is thought to be located in Sub-Saharan Africa–meaning below the Sahara, the largest hot desert on earth. So how was humanity able to breach such an intimidating barrier to spread out across the rest of the world?

Until now, anthropologists typically argued that hominids could only have followed the lush Nile River valley north in order to reach the Middle East and beyond. But new research is suggesting that the Sahara might not have been an impassable barrier to those humans after all. Some animals (including several fish species) are found on both the north and south sides of the desert, and even in some safe-haven ponds in between. The researchers argue that if these ancestral fish could swim across the region that we now know as the Sahara, humans could have also made it across.

“Fish appeared to have swam across the Sahara during its last wet phase sometime between 10,000 and 6,000 years ago,” researcher Nick Drake, a geographer at King’s College London, told LiveScience. “The Sahara is not a barrier to the migrations of animals and people. Thus it is possible–likely?–that early modern humans did so, and this could explain how we got out of Africa.” [LiveScience]

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CATEGORIZED UNDER: Human Origins, Living World

Prehistoric Rock Art Owes Its Colors to Thriving Microbial Colonies

By Eliza Strickland | December 29, 2010 1:07 pm

A particular set of rock paintings dating from more than 40,000 years ago don’t seem to be made of paint anymore. According to a new study published in the journal Antiquity, the vibrant artworks were long ago colonized by colorful microbes, which serve as “living pigments” in the paintings. Lead researcher Jack Pettigrew, of the University of Queensland in Australia, explains:

“‘Living pigments’ is a metaphorical device to refer to the fact that the pigments of the original paint have been replaced by pigmented micro-organisms…. These organisms are alive and could have replenished themselves over endless millennia to explain the freshness of the paintings’ appearance.” [BBC News]

When the researchers analyzed the so-called Bradshaw rock artworks found in Western Australia’s Kimberley region, they didn’t find paint. Instead they found a black fungus, probably belonging to a fungi group known as Chaetothyriales, as well as a reddish organism that is suspected to be a species of cyanobacteria.

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CATEGORIZED UNDER: Human Origins, Living World

Devastated Brown Bats Could Earn Endangered Species Protection

By Andrew Moseman | December 29, 2010 10:58 am

The continued onslaught by white nose syndrome against North America’s bats is one of the stories of the year—number 13, in fact, on DISCOVER’s Top 100 of 2010. But some help soon could be on the way in the form of Endangered Species Act protection. Earlier this month, a group of conservationists and scientists filed an emergency petition with the United States Fish and Wildlife Service to list the little brown bat under the act.

Emergency listing for a species does happen, but not very often, says Ann Froschauer, national white-nose syndrome communications leader for FWS. “Given the urgency of white-nose syndrome and recent information about predicted declines in little brown bat populations, the Service is committed to quickly reviewing scientific information, both published and provided by organizations such as these, in assessing the status of little brown bats and other bat species affected by WNS.” [Scientific American]

Listing the bats as endangered could force government action to protect them, including increased funding and the designation of critical habitat.

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CATEGORIZED UNDER: Living World

Why 98.6 Degrees? Our Body Temperature Strikes a Perfect Balance

By Andrew Moseman | December 28, 2010 3:42 pm

Standard human body temperature is 98.6 degrees Fahrenheit: It’s one of those numbers from grade school science textbooks—like 65 million years since the dinosaur extinction or nine eight planets in the solar system—that just gets stuck in your head. But why should it be that balmy temperature and no other?

According to a study by researchers at Albert Einstein College of Medicine, the 98-degree range is in perfect balance.

Every one degree Celsius rise in body temperature wards off about 6 percent more fungal species. So tens of thousands of fungi can infect reptiles and amphibians, but we can only be invaded by a few hundred fungi. In the new work, the researchers created a mathematical model that weighed the fungal protection benefits versus the metabolic cost of high body temperature. And the optimal temperature was 98.1, quite close to what evolution figured out. [Scientific American]

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CATEGORIZED UNDER: Health & Medicine
MORE ABOUT: fungus, metabolism

Omnivorous Neanderthals: Study Says Their Teeth Show Evidence of Eating Plants

By Andrew Moseman | December 28, 2010 12:35 pm

Did Neanderthals enjoy some diversity in their diet? A study out in this week’s Proceedings of the National Academy of Sciences claims to offer more evidence that these hominids ate a wide-ranging diet including cooked grains and grasses rather than the cartoon caveman’s diet of meat, meat, and more meat.

Amanda Henry has made the case before; in April 2008 she said that micro-fossils of plant material could be found in the plaque of recovered Neanderthal teeth. Now, she says, her team has found more traces of grains and plants stuck in the teeth of Neanderthal fossils unearthed in Belgium and Iraq.

After analyzing a selection of these particles from European and Middle Eastern Neandertal dental remains, the team found “direct evidence for Neanderthal consumption of a variety of plant foods.” … Some of the Paleolithic snacks seem to have included legumes, date palms and grass seeds. The grasses were from the Triticeae group, which includes wild varieties of barley, rye and wheat relatives. [Scientific American]

Furthermore, the grains and starches present show the signature of having been cooked—probably by boiling in water—according to study author Dolores Piperno. To test this out the researchers themselves cooked similar grains, and the effects matched what they saw in the Neanderthal samples.

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CATEGORIZED UNDER: Human Origins, Top Posts

Cassini Catches a Glimpse of an Enormous Storm on Saturn

By Andrew Moseman | December 28, 2010 9:48 am

A new sight appeared on Saturn earlier this month: A massive, swirling storm with a tail that cuts across the gas giant. Amateur astronomer Anthony Wesley, who was the first to spot the Earth-sized scar on Jupiter last summer, took the first pictures of this storm. And then on Christmas Eve the Cassini spacecraft beamed home its own ravishing images.

From Phil Plait:

The spacecraft took images of the planet on December 24th, returning — as usual — jaw-dropping pictures of Saturn showing the storm. This image, taken with a blue filter, shows the storm clearly. The main spot is huge, about 6,000 km (3600 miles) across — half the size of Earth! Including the tail streaming off to the right, the whole system is over 60,000 km (36,000 miles) long.

There’s an added bonus in these images: the shadow of the rings on the planet’s clouds is obvious, but the rings are nearly invisible! You can just make out the rings as a thin line going horizontally across Saturn in the first image. These pictures were snapped when Cassini was almost directly above the rings, which are so thin they vanish when seen edge-on. Actually, that works out well as otherwise they might interfere with the view of the storm in these shots.

For more details, check out the rest of Phil’s post at Bad Astronomy.

Related Content:
80beats: By Demolishing a Moon, Saturn May Have Created Its Rings
80beats: Mysterious Smash on Jupiter Leaves an Earth-Sized Scar
Bad Astronomy: Saturn rages from a billion kilometers away

Image: NASA

CATEGORIZED UNDER: Space

Supersized Amygdalas Linked to Sprawling Social Circles

By Andrew Moseman | December 27, 2010 2:20 pm

Large amygdalas, it seems, are social amygdalas.

These paired regions, typically referred to as almond-shaped (indeed their name comes from the Greek for almond), are known to be part of the brain responsible for sociability as well as fear and other deep-seated emotions. Lisa Feldman Barrett and colleagues sought to find out whether size matters in the amygdala, and according to their study in Nature Neuroscience, there is a connection between people having big amygdalas and having big, complex social networks.

The researchers measured two social network factors in 58 adults. First, they calculated the size of a participant’s network, which is simply the total number of people that are in regular contact with the participant. Second, they measured the network’s complexity, based on how many different groups a participant’s contacts can be divided into. … Linear regression revealed a positive correlation in amygdala size with both social network size and complexity. [Ars Technica]

The team’s MRI scans found a wide variation in amygdala size, from about 2.5 cubic millimeters to more than five. But other factors like a person’s happiness didn’t match up with amygdala size. And the subjects’ hippocampus, which the scientists used as a control, showed no variation when compared to a person’s social network. Only the amygdala size showed the connection, Barrett says.

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CATEGORIZED UNDER: Mind & Brain

Uh Oh: Pollen Can Spread Viruses From Domesticated Bees to Wild Ones

By Andrew Moseman | December 27, 2010 12:43 pm

More trouble for bees: A study out in the open-access journal PLoS One finds that viruses that previously had been the bane of domesticated honeybees have spread to wild pollinators.

A pattern showed up in the survey that fits that unpleasant scenario. Researchers tested for five viruses in pollinating insects and in their pollen hauls near apiaries in Pennsylvania, New York and Illinois. Israeli acute parasitic virus (IAPV) showed up in wild pollinators near honeybee installations carrying the disease but not near apiaries without the virus. In domestic honeybees, such viruses rank as one of the possible contributors to the still-mysterious malady known as colony collapse disorder that abruptly wipes out a hive’s workforce, [study author Diana] Cox-Foster says. [Science News]

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CATEGORIZED UNDER: Living World

California Mine Aims To Challenge China's Rare Earth Supremacy

By Andrew Moseman | December 27, 2010 11:07 am

Renewable energy, information technology, and many other industries are in a political and economic bind—they require the obscure periodic table denizens called rare earth metals, and nearly all the world’s supply of those elements comes from China. But now, for the first time in years, rare earth elements will be mined at an American site. The mining company Molycorp says it has the permits in hand to reopen a mine in Mountain Pass, California, that could soon meet much of the U.S. demand for these elements.

The materials that come out of Mountain Pass will be used to make high-strength magnets necessary for electric vehicle engines, wind turbines, and a variety of other high-tech products. However, the U.S. possesses neither the technology nor the licensing to manufacture the neodymium-iron-boron alloy necessary for their production. As such, Molycorp has partnered with Japanese firm Hitachi Metals to manufacture the magnets in the United States. [Popular Science]

After its projected 2012 opening, the Molycorp mine should produce about 20,000 tons of material per year, the company says. Right now the world’s demand stands at about 125,000 tons per year, and Technology Review reports that this number could jump to 225,000 in five years. China has a stranglehold on the rare earth market, meaning political maelstroms could disrupt the supply.

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CATEGORIZED UNDER: Environment, Technology

Study: Placebos Can Work Even if Patients Know They're Placebos

By Andrew Moseman | December 27, 2010 9:56 am

You’ve heard of the placebo effect—the tendency for patients who receive a phony treatment like a sugar pill to feel better just because they think the treatment will help them. That standard definition relies on deception. Surely the placebo effect doesn’t work if you tell the patients they’re taking placebos, right?

Not necessarily, a new study finds. And, as DISCOVER blogger Ed Yong notes, this brings up an interesting ethical question:

Can doctors justifiably prescribe placebos to their patients? The standard answer is no. Doing so patronises the patient, undermines their trust, and violates the principles of informed consent. It compromises the relationship between doctor and patient. At worst, it could do harm.

But many of these arguments are based on the idea that placebo effects depend on belief; people must expect that treatments will work in order to experience any benefits. For a doctor to prescribe a placebo, they’d need to deceive. But according to Ted Kaptchuk from Harvard Medical School, deception may not be necessary. In a clinical trial, he found that patients with irritable bowel syndrome (IBS) felt that their symptoms improved when they took placebo pills, even if they were told that the pills were inactive.

For plenty more about this, check out the rest of Ed’s post at Not Exactly Rocket Science.

Related Content:
Not Exactly Rocket Science: The Placebo Effect Affects Pain Signaling in the Spine
Not Exactly Rocket Science: A Biological Basis for Acupuncture, or More Evidence for a Placebo Effect?
80beats: 50% of U.S. Doctors Secretly Dose Their Patients—With the Placebo Effect
DISCOVER: Is the Placebo Effect a Myth?

Image: flickr/Fillmore Photography

CATEGORIZED UNDER: Health & Medicine
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