Posts Tagged ‘Africa’

Chunks of clay excavated from Iron Age grain bins in South Africa. Early farmers burnt their clay huts and grain storage buildings in times of drought as part of a cleansing ritual, unknowingly locking the magnetic properties of the minerals in the clay into place.

A flip in Earth’s magnetic field may be brewing. And if it is, an electromagnetic blob deep under southern Africa is likely to be ground zero for the change.

New research using clays burned in cleansing rituals by Iron Age farmers finds that over the past 1,500 years, an electromagnetic anomaly in the Southern Hemisphere has waxed and waned, with the magnetic field in the region weakening and strengthening. This weirdness may presage a gradual reversal in the magnetic field, so that magnetic north moves to the South Pole and vice versa. (A flip-flop of this sort last occurred 780,000 years ago.)

The study suggests that the magnetic field under southern Africa may not just be weird today, study co-author John Tarduno, who researches the Earth’s magnetism at the University of Rochester in New York, told Live Science. It may be a longstanding hotspot for changes in the global magnetic field.


The planet’s magnetic field is generated by the churning of liquid iron in the core. Without the field, life on the planet would be much different, if not impossible: This invisible shield protects the Earth’s surface from deadly cosmic radiation.

Right now, the field is undergoing a weakening, and no one is sure why. The South Atlantic Anomaly, a region of the magnetic field that stretches from South Africa to Chile, is particularly weak, Tarduno said, so scientists have become interested in figuring out what might be going on in the core underneath that area.

The problem is that before about 160 years or so ago, with the advent of magnetic observatories and (eventually) satellite observations, there weren’t many records of what the magnetic field looked like in the Southern Hemisphere, Tarduno said. Ninety percent of the data that does exist comes from the northern half of the planet. To start to rectify that disparity, Tarduno and his team excavated clays from the Limpopo River Valley of Zimbabwe, South Africa, and Botswana. In times of drought hundreds to thousands of years ago, Bantu-speaking farmers would burn down their clay huts and grain bins in ritualistic ceremonies. Unbeknown to these ancient farmers, the fire heated the magnetic minerals in the clay and locked into place a record of the strength and orientation of the field at that time. Now, researchers can study those properties to find out what the magnetic field was doing at that moment in time.


The excavations unearthed these burnt clays as long ago as A.D. 425, Tarduno said, providing the longest record yet of the magnetic field in southern Africa. The data show that the magnetic field experienced sudden directional shifts between A.D. 400 and 450, and then again between A.D. 750 and 800. Between about A.D. 1225 and 1550, the field noticeably weakened. The first two shifts might also indicate a weakened field, Tarduno said, but more research is needed to determine the magnetic intensity in those time frames. The researchers reported their findings Feb. 15 in the journal Geophysical Research Letters.

What these shifts suggest is that what is going on in the Southern Hemisphere’s magnetic field today may have happened before, Tarduno said.

The field shifts may have to do with underlying processes churning deep beneath the Earth’s surface, Tarduno said. In recent years, scientists have documented a weird patch of magnetic field below southern Africa at the boundary between the core and the mantle, where the polarity of the field is reversed.

“That patch may be largely responsible for the decreasing magnetic field,” Tarduno said.

The patch is like an eddy in a stream, he said. As for what causes the eddy, it may be something odd about the mantle right above the core in that location, he said. The mantle under southern Africa is unusual, and possibly both hotter and denser than surrounding mantle, he said.

“We think that is causing there to be changes in the flow of the iron [in the core] as it enters this region,” Tarduno said.

That could mean that southern Africa is the origin for magnetic field reversals, Tarduno said, though there’s no guarantee that the field will flip now — the weakening could also dissipate, as it has in centuries past.

Even if the field doesn’t reverse, though, the weakening itself could have societal implications, Tarduno said.

“These are not of the nature of disaster movies. That’s not the point,” he said. Instead, a weakening field could let more cosmic radiation hit the Earth, making infrastructure like the power grid more susceptible to geomagnetic storms and even changing atmospheric chemistry so that more UV rays could sneak through, causing increased risk for skin cancer in humans.

“It’s definitely something that we need to keep an eye on,” Tarduno said.


By Traci Watson, National Geographic

Don’t blame the lure of a glowing smartphone for keeping you up too late. Even people without modern technology don’t sleep the night away, new research says.

Members of three hunter-gatherer societies who lack electricity—and thus evenings filled with Facebook, Candy Crush, and 200 TV channels—get an average of only 6.4 hours of shut-eye a night, scientists have found. That’s no more than many humans who lead a harried industrial lifestyle, and less than the seven to nine hours recommended for most adults by the National Sleep Foundation.

People from these groups—two in Africa, one in South America—tend to nod off long after sundown and wake before dawn, contrary to the romantic vision of life without electric lights and electronic gadgets, the researchers report in Thursday’s Current Biology.

“Seeing the same pattern in three groups separated by thousands of miles on two continents (makes) it pretty clear that this is the natural pattern,” says study leader and sleep researcher Jerome Siegel of the University of California, Los Angeles. “Maybe people should be a little bit more relaxed about sleeping. If you sleep seven hours a night, that’s close to what our ancestors were sleeping.”

Previous research has linked lack of sleep to ills ranging from poor judgment to obesity to heart disease. The rise of mesmerizing electronic devices small enough to carry into bed has only heightened worries about a modern-day epidemic of bad sleep. One recent study found that after bedtime sessions with an eBook reader, test subjects took longer to fall asleep and were groggier in the morning than when they’d curled up with an old-fashioned paper book.

Many scientists argue that artificial lighting curtailed our rest, leading to sleep deficits. But Siegel questioned that storyline. He was studying the sleep of wild lions when he got the inspiration to monitor the sleep of pre-industrial people, whose habits might provide insight into the slumber of early humans.

Siegel and his colleagues recruited members of Bolivia’s Tsimane, who hunt and grow crops in the Amazonian basin, and hunter-gatherers from the Hadza society of Tanzania and the San people in Namibia. These are among the few remaining societies without electricity, artificial lighting, and climate control. At night, they build small fires and retire to simple houses built of materials such as grass and branches.

The researchers asked members of each group to wear wristwatch-like devices that record light levels and the smallest twitch and jerk. Many Tsimane thought the request comical, but almost all wanted to participate, says study co-author Gandhi Yetish of the University of New Mexico. People in the study fell asleep an average of just under three and a half hours after sunset, sleep records showed, and mostly awakened an average of an hour before sunrise.

The notable slugabeds are the San, who in the summer get up an hour after sunrise. The researchers noticed that at both the San and Tsimane research sites, summer nights during the study period lasted 11 hours, but mornings were chillier in the San village. That fits with other data showing the three groups tend to nod off when the night grows cold and rouse when temperature bottoms out before dawn.

Our time to wake and our time to sleep, Siegel says, seem to be dictated in part by natural temperature and light levels—and modern humans are divorced from both. He suggests some insomniacs might benefit from re-creating our ancient exposure to warmth and cold.



by Pallab Ghosh
Science correspondent, BBC News, Johannesburg

Scientists have discovered a new human-like species in a burial chamber deep in a cave system in South Africa. The discovery of 15 partial skeletons is the largest single discovery of its type in Africa.

The researchers claim that the discovery will change ideas about our human ancestors.

The studies which have been published in the journal Elife also indicate that these individuals were capable of ritualistic behaviour.

The species, which has been named naledi, has been classified in the grouping, or genus, Homo, to which modern humans belong.

The researchers who made the find have not been able to find out how long ago these creatures lived – but the scientist who led the team, Prof Lee Berger, told BBC News that he believed they could be among the first of our kind (genus Homo) and could have lived in Africa up to three million years ago.

Like all those working in the field, he is at pains to avoid the term “missing link”. Prof Berger says naledi could be thought of as a “bridge” between more primitive bipedal primates and humans.

“We’d gone in with the idea of recovering one fossil. That turned into multiple fossils. That turned into the discovery of multiple skeletons and multiple individuals.

“And so by the end of that remarkable 21-day experience, we had discovered the largest assemblage of fossil human relatives ever discovered in the history of the continent of Africa. That was an extraordinary experience.”

Prof Chris Stringer of the Natural History Museum said naledi was “a very important discovery”.

“What we are seeing is more and more species of creatures that suggests that nature was experimenting with how to evolve humans, thus giving rise to several different types of human-like creatures originating in parallel in different parts of Africa. Only one line eventually survived to give rise to us,” he told BBC News.

I went to see the bones which are kept in a secure room at Witwatersrand University. The door to the room looks like one that would seal a bank vault. As Prof Berger turned the large lever on the door, he told me that our knowledge of very early humans is based on partial skeletons and the occasional skull.

he haul of 15 partial skeletons includes both males and females of varying ages – from infants to elderly. The discovery is unprecedented in Africa and will shed more light on how the first humans evolved.

“We are going to know everything about this species,” Prof Berger told me as we walked over to the remains of H. naledi.

“We are going to know when its children were weaned, when they were born, how they developed, the speed at which they developed, the difference between males and females at every developmental stage from infancy, to childhood to teens to how they aged and how they died.”

I was astonished to see how well preserved the bones were. The skull, teeth and feet looked as if they belonged to a human child – even though the skeleton was that of an elderly female.
Its hand looked human-like too, up to its fingers which curl around a bit like those of an ape.

Homo naledi is unlike any primitive human found in Africa. It has a tiny brain – about the size of a gorilla’s and a primitive pelvis and shoulders. But it is put into the same genus as humans because of the more progressive shape of its skull, relatively small teeth, characteristic long legs and modern-looking feet.

“I saw something I thought I would never see in my career,” Prof Berger told me.

“It was a moment that 25 years as a paleoanthropologist had not prepared me for.”

One of the most intriguing questions raised by the find is how the remains got there.

I visited the site of the find, the Rising Star cave, an hour’s drive from the university in an area known as the Cradle of Humankind. The cave leads to a narrow underground tunnel through which some of Prof Berger’s team crawled in an expedition funded by the National Geographic Society.

Small women were chosen because the tunnel was so narrow. They crawled through darkness lit only by their head torches on a precarious 20 minute-long journey to find a chamber containing hundreds of bones.

Among them was Marina Elliott. She showed me the narrow entrance to the cave and then described how she felt when she first saw the chamber.

“The first time I went to the excavation site I likened it to the feeling that Howard Carter must have had when he opened Tutankhamen’s tomb – that you are in a very confined space and then it opens up and all of a sudden all you can see are all these wonderful things – it was incredible,” she said.

Ms Elliott and her colleagues believe that they have found a burial chamber. The Homo naledi people appear to have carried individuals deep into the cave system and deposited them in the chamber – possibly over generations.

If that is correct, it suggests naledi was capable of ritual behaviour and possibly symbolic thought – something that until now had only been associated with much later humans within the last 200,000 years.

Prof Berger said: “We are going to have to contemplate some very deep things about what it is to be human. Have we been wrong all along about this kind of behaviour that we thought was unique to modern humans?

“Did we inherit that behaviour from deep time and is it something that (the earliest humans) have always been able to do?”

Prof Berger believes that the discovery of a creature that has such a mix of modern and primitive features should make scientists rethink the definition of what it is to be human – so much so that he himself is reluctant to describe naledi as human.

Other researchers working in the field, such as Prof Stringer, believe that naledi should be described as a primitive human. But he agrees that current theories need to be re-evaluated and that we have only just scratched the surface of the rich and complex story of human evolution.


by Richard Knox

It’s only a matter of time, some researchers are warning, before isolated cases of Ebola start turning up in developed nations, as well as hitherto-unaffected African countries.

The current Ebola outbreak in West Africa has killed more people than all previous outbreaks combined, the World Health Organization said Wednesday. The official count includes about 3,600 cases and 1,800 deaths across four countries.

Meanwhile, the authors of a new analysis say many countries — including the U.S. — should gear up to recognize, isolate and treat imported cases of Ebola.

The probability of seeing at least one imported case of Ebola in the U.S. is as high as 18 percent by late September, researchers reported Tuesday in the journal PLOS Currents: Outbreaks. That’s compared with less than 5 percent right now.

These predictions are based on the flow of airline passengers from West Africa and the difficulty of preventing an infected passenger from boarding a flight.

As with any such analysis, there’s some uncertainty. The range of a probable U.S. importation of Ebola by Sept. 22 runs from 1 percent to 18 percent. But with time — and a continuing intense outbreak in West Africa — importation is almost inevitable, the researchers told NPR.

“What is happening in West Africa is going to get here. We can’t escape that at this point,” says physicist Alessandro Vespignani, the senior author on the study, who analyzes the spread of infectious diseases at Northeastern University.

To be clear, the projection is for at least one imported case of Ebola — not for the kind of viral mayhem afflicting Guinea, Liberia and Sierra Leone.

“What we could expect, if there is an importation, would be very small clusters of cases, between one and three,” Vespignani says.

But the probability increases as long as the West African epidemics keep growing. And that means U.S. hospitals, doctors and public health officials need to heighten their vigilance.

The same is true for a roster of 16 other nations, from the U.K. to South Africa, which are connected to West Africa through air traffic, Vespignani and his colleagues say.

There’s a 25 to 28 percent chance that an Ebola case will turn up in the U.K. by late September. Belgium, France and Germany will have lower risk. “But it’s not negligible,” Vespignani says. “Sooner or later, they will arrive.”

The probability of imported cases in Africa is higher, not surprisingly. There’s more than a 50 percent probability Ebola will show up in the West African nation of Ghana by late September, according to the study. Gambia, Ivory Coast, Morocco, South Africa and Kenya are among 11 African countries where Ebola could pop up.

Officials at the U.S. Centers for Disease Control and Prevention had a presentation on the numbers on Tuesday. The CDC has deployed teams of personnel in West Africa to help bring Ebola under control. And here at home, the agency is charged with preparing both the U.S. medical system and the American public for the possibility that the deadly virus could sneak into this country.

Biostatistician Ira Longini from the University of Florida agrees that Ebola doesn’t pose a public health threat in the U.S. and other developed nations. But that doesn’t mean that preparation isn’t urgent.

“We certainly need to make sure that staff and leadership of American medical centers understand the implications of Ebola,” says Longini, who also worked on the study. “We need to have diagnostics in place to identify Ebola quickly. We need quite a few local labs to do this and not just rely on sending samples to the CDC. And we need to make sure isolation and quarantine of contacts takes place. If it doesn’t, we could have a small cluster of cases.”

The analysis by Longini, Vespignani and their colleagues takes into account the number of airline passengers coming from West Africa to various countries. For instance, more than 6,000 a week arrive in Britain from Nigeria, many of them originating in other African countries.

Hundreds to several thousands travel every week from West Africa to France, Germany, Spain, Italy, South Africa, Egypt, Saudi Arabia, India, China and other countries.

The researchers calculated the impact of severe restrictions on flights from Ebola-affected regions. An 80 percent reduction in air travelers would do no more than delay the impact of Ebola by a few weeks. (A 100 percent choke-off of air travel is considered impossible.)

“Unless you can completely shut down the transportation systems, these kinds of efforts will, at best, buy you a little time,” Longini says. “And they can be quite counterproductive because you’re interrupting the flow of help, goods and services. It can make the epidemic worse in the country that’s being quarantined.”

The basic problem with confining Ebola is that, like any infectious disease, people can be infected without showing symptoms. In Ebola’s case, the average incubation period is 7 days, though it can be longer. That’s more than enough time for an infected traveler to land on the other side of the world.

Fortunately, an Ebola-infected person can’t infect others unless he’s obviously sick. At that stage, the virus can spread by direct contact with the infected person or bodily fluids. On average, each case of Ebola infects about two other people. That spread rate is similar to that of the flu, and roughly half the rate of smallpox.

Vespignani, from Northeastern University, says screening airline passengers is not going to prevent Ebola from traveling across the globe. “I don’t trust screening too much,” he says. “It’s difficult. Intercepting passengers that are really not sick is not easy.”

Thanks to Ray Gaudette for bringing this to the attention of the It’s Interesting community.


Because Kent Brantly is a physician who has watched people die of Ebola, there was an especially chilling prescience to his assessment last week, between labored breaths: “I am going to die.”

His condition was grave. But then on Saturday, we saw images of Brantly’s heroic return to U.S. soil, walking with minimal assistance from an ambulance into an isolation unit at Emory University Hospital.

“One of the doctors called it ‘miraculous,'” Dr. Sanjay Gupta reported from Emory this morning, of Brantly’s turnaround within hours of receiving a treatment delivered from the U.S. National Institutes of Health. “Not a term we scientists like to throw around.”

“The outbreak is moving faster than our efforts to control it,” Dr. Margaret Chan, director of the World Health Organization, said on Friday in a plea for international help containing the virus. “If the situation continues to deteriorate, the consequences can be catastrophic in terms of lost lives, but also severe socioeconomic disruption and a high risk of spread to other countries.”

In that light, and because Ebola is notoriously incurable (and the strain at large its most lethal), it is overwhelming to hear that “Secret Serum Likely Saved Ebola Patients,” as we do this morning from Gupta’s every-20-minute CNN reports. He writes:

Three top secret, experimental vials stored at subzero temperatures were flown into Liberia last week in a last-ditch effort to save two American missionary workers [Dr. Kent Brantly and Nancy Writebol] who had contracted Ebola, according to a source familiar with details of the treatment.

Brantly had been working for the Christian aid organization Samaritan’s Purse as medical director of the Ebola Consolidation Case Management Center in Monrovia, Liberia. The group yesterday confirmed that he received a dose of an experimental serum before leaving the country.

In Gupta’s optimistic assessment, Brantly’s “near complete recovery” began within hours of receiving the treatment that “likely saved his life.” Writebol is also reportedly improved since receiving the treatment, known as zMapp. But to say that it was a secret implies a frigid American exceptionalism; that the people of West Africa are dying in droves while a classified cure lies in wait.

The “top-secret serum” is a monoclonal antibody. Administration of monoclonal antibodies is an increasingly common but time-tested approach to eradicating interlopers in the human body. In a basic monoclonal antibody paradigm, scientists infect animals (in this case mice) with a disease, the mice mount an immune response (antibodies to fight the disease), and then the scientists harvest those antibodies and give them to infected humans. It’s an especially promising area in cancer treatment.

In this case, the proprietary blend of three monoclonal antibodies known as zMapp had never been tested in humans. It had previously been tested in eight monkeys with Ebola who survived—though all received treatment within 48 hours of being infected. A monkey treated outside of that exposure window did not survive. That means very little is known about the safety and effectiveness of this treatment—so little that outside of extreme circumstances like this, it would not be legal to use. Gupta speculates that the FDA may have allowed it under the compassionate use exemption.

A small 2012 study of monoclonal antibody therapy against Ebola found that it was only effective when administered before or just after exposure to the virus. A 2013 study found that rhesus macaques given an antibody mix called MB-003 within the 48-hour window had a 43 percent chance of surviving—as opposed to their untreated counterparts, whose survival rate was zero.

This Ebola outbreak is the largest in the history of the disease, in terms of both cases and deaths, 729 887 known so far. As Chan warned in her call for urgent international action, the outbreak is geographically the largest, already in four countries with fluid population movement across porous borders and a demonstrated ability to spread by air travel. The outbreak will be stopped by strategic quarantines and preventive education, primarily proper handling of corpses. More than 60 aid workers have become infected, but many more will be needed to stem the tide.

Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Disease (NIAID), is encouraged by the antibody treatment.

“Obviously there are plans and enthusiasm to expand this,” Fauci told me. “The limiting factor is the extraordinary paucity of treatment regimens.” Right now the total amount available, to Fauci’s knowledge, is three treatment courses (in addition to what was given to Brantly and Writebol).

NIAID did some of the original research that led to the development, but this is owned by Mapp Biopharmaceuticals. “They are certainly trying to scale up,” Fauci said, “but I’ve heard that their capability is such that it’s going to be months before they have a substantial number of doses, and even then they’re going to be limited.”

“We’re hearing that the administration of this cocktail of antibodies improved both Dr. Brantly and Ms. Writebol, but you know, we don’t know that,” Fauci said, noting the sample size (two) of this small, ad hoc study. Proving effectiveness would require a much larger group of patients being compared to an untreated group. “And we don’t know that they weren’t getting better anyway.”

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.