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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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“‘Living pigments’ is a metaphorical device to refer to the fact that the pigments of the original paint have been replaced by pigmented micro-organisms….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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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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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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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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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.
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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.
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Image: NASA
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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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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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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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.
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Image: flickr/Fillmore Photography
Coal ash: Two years after the coal ash spill in Roane County, Tennessee residents are still grappling with ash dust, housing buyouts, and potentially toxic water. The Tennessee Valley Authority, a government-owned corporation who runs the plant, claims the ash is non-toxic, while the EPA takes it’s time deciding if it should be classified as hazardous waste.
Wolves: Activist group Center For Biological Diversity is planning to sue the Department of the Interior if they don’t expand wolf ranges in the lower 48. Some states in the Northern Rocky Mountains, where the population has made a comeback, have legalized hunting to protect their herds.
Elephant genomes: New genetics data is showing that the African elephant is actually two species: the forest elephant is smaller than the savanna elephant and has a much smaller population. Dividing the “African elephant” into two species is going to be important to conservation of the forest elephant’s habitat and save them from poachers.
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Some of the consequences of ocean acidification appear obvious: The shells of mollusks, for instance, could dissolve as the pH of ocean water drops thanks to the ocean pulling out some of the excess carbon dioxide humans put into the atmosphere. But what about more subtle effects of seawater growing more acidic?
In the Proceedings of the National Academy of Sciences this week, researchers set up an experiment to see whether the growing acidity of the ocean could disrupt the marine cycle of nitrogen, which provides key nutrients for plant life. Indeed it can, J. Michael Beman’s team found, and that’s another potentially dangerous side effect of the ocean as a carbon sink.
The authors of the study examined a specific step in the marine nitrogen cycle, called nitrification, in which microorganisms convert one form of nitrogen, ammonium, into nitrate, a form plants and other marine microorganisms require to survive. Previous research studies on experimentally acidified freshwater … in the laboratory have suggested that reduced pH slows nitrification, and one study in coastal ocean waters showed that large pH decreases did the same. [Scientific American]
So Beman sought to test the ocean by gathering samples of seawater from locations around the world and adding CO2 to simulate what will be happening to the oceans in the coming decades. Just decreasing the pH from 8.1 to 8.0 resulted in about 20 percent less nitrate creation, the team wrote. In their experiments that lowered pH between .05 and .14, the nitrate production dropped between 8 and 38 percent.
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Do bees prefer certain colors or shapes in the flowers from which they forage? And can they learn on the fly to go to certain colors or shapes that prove to be more lucrative?
That was the question for the students of Blackawton Primary School in Devon, England. And by devising a clever experiment to find out, these kids became the youngest authors ever to have a study published in a journal of Britain’s Royal Society.
From Ed Yong:
Their paper, based on fieldwork carried out in a local churchyard, describes how bumblebees can learn which flowers to forage from with more flexibility than anyone had thought. It’s the culmination of a project called ‘i, scientist’, designed to get students to actually carry out scientific research themselves. The kids received some support from Beau Lotto, a neuroscientist at UCL, and David Strudwick, Blackawton’s head teacher. But the work is all their own.
The class (including Lotto’s son, Misha) came up with their own questions, devised hypotheses, designed experiments, and analysed data. They wrote the paper themselves (except for the abstract), and they drew all the figures with colouring pencils.
For all the details about this class experiment turned published study, check out the rest of Ed’s post at Not Exactly Rocket Science.
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Image: Wikimedia Commons
It’s beginning to look a lot like… self-inflicted doom.
This week Associated Press reporters tallied the toll of the year in natural disasters, and it added up to some depressing results. Around the world—in Haiti and Chile earthquakes, in Pakistani floods, in Russian heat waves—nature unleashed its fury in extreme fashion in 2010, the AP says, and humans made it worse through our own actions.
“It just seemed like it was back-to-back and it came in waves,” said Craig Fugate, who heads the U.S. Federal Emergency Management Agency. It handled a record number of disasters in 2010. “The term ’100-year event’ really lost its meaning this year.” [AP]
At least 250,000 people died in natural disasters this year, up from just 15,000 last year. But, the AP’s Seth Bornstein argues, this isn’t just natural variability.
For one thing, there are the avoidable problems of not doing enough to prepare for the inevitable appearance of disaster. The 2010 death toll is skewed so high this year because of the Haiti earthquake in January that killed most of the people in that quarter-million group. There’s nothing to be done about the shifts of tectonic plates, but the death toll skyrocketed because so many poor Haitians were living in such poorly built dwellings. The more powerful Chilean earthquake, by contrast, occurred in a place with better-built structures and killed fewer than a thousand. While in Pakistan, having so many homes in the flood zone exacerbated the damage when the monsoons came in July.
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It’s the chilly winter solstice and the eclipse of the moon happened in the wee hours of this morning, so plenty of people probably didn’t sacrifice sleep and stand out in the cold to watch the sky show. No worries—those who did stay up took pictures.
This eclipse was visible across much of Europe, the Americas and parts of Asia. And it was more unusual than most because it coincided with the winter solstice and today’s official start of winter. [NPR]
Such an astronomical alignment hasn’t happened in centuries, and most people alive today won’t be around for the next one: It doesn’t happen again until 2094. Those who braved the cold and had clear viewing skies got to enjoy hours of the eclipse, as the Earth’s shadow began to fall on our natural satellite during the 1 a.m. hour Eastern time.
The total eclipse began about 2:40 a.m. and lasted 72 minutes, until 3:52 a.m. The moon then continued moving through the Earth’s shadow, emerging completely sometime after 5 a.m. The winter solstice, which occurs later in the day, is the time when the sun reaches its lowest point in the northern sky. The Naval Observatory said this year’s solstice will be at 6:38 p.m. [Washington Post]
But why is the moon bathed in blood red light?
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