Ancient Toolkit Gives Glimpse of Prehistoric Life
Toolkit Contents
The owner of a 14,000-year-old bag was well equipped for hunting and gathering. The contents, pictured, here, include a sickle for harvesting wild plants, a cluster of flint spearheads, a flint core for making more spearheads, a cluster of gazelle toe bones, and part of a second bone tool.
Before the end of the last ice age, a hunter-gatherer left a bag of tools near the wall of a roundhouse residence, where archaeologists have now found the collection 14,000 years later.
The tool set -- one of the most complete and well preserved of its kind -- provides an intriguing glimpse of the daily life of a prehistoric hunter-gatherer.
The contents, as described to Discovery News by Phillip Edwards, a senior lecturer in the Archaeology Program at Melbourne's La Trobe University, show the owner of the bag was well equipped for obtaining meat and edible plants in the wild.
"There was a sickle for harvesting wild wheat or barley, a cluster of flint spearheads, a flint core for making more spearheads, some smooth stones (maybe slingshots), a large stone (maybe for striking flint pieces off the flint core), a cluster of gazelle toe bones which were used to make beads, and part of a second bone tool," he said.
Edwards outlines the finds, attributed to the Natufian culture from a site called Wadi Hammeh 27 in Jordan, in the latest issue of Antiquity.
He believes the tools were enclosed in a hide or wickerwork bag with a strap that would have been worn over the shoulder. Such bags rarely had compartments, so the owner probably protected valuable items by wrapping them in rolls of bark or leather before placing them at the bottom of the bag.
The sickle, constructed out of two carefully grooved horn pieces, was fitted with color-matched tan and grey bladelets. It would have been a marvel of form and function for its day and is the only tool of its kind ever linked to the Natufian people.
The rest of the items were designed to immobilize and then kill game such as aurochs, red deer, hares, storks, partridges, owls, tortoises and the major source of meat -- gazelles.
"A lone hunter or a group of hunters might wait for gazelles to cross their path while waiting behind a low 'hide' made of twigs and brush," Edwards explained.
"They might have worked on making bone beads to wile away the time. Then a hunter could get off a shot while the animals were off their guard. A first shot might wound, but not kill, and then a hunter or a group of them will track the wounded animal."
He added, "We don't know if Natufian hunters had the bow and arrow, or just spears."
The mountain gazelles targeted by the Near Eastern hunters probably weighed between 39 and 55 pounds, so a strong adult "could carry an entire carcass over his shoulders without much trouble."
But the bag's owner wasn't necessarily a man; women are thought to have been in charge of plant gathering. The tools, therefore, either belonged to a woman hunter-gatherer, or work activities were more gender-blind than thought during prehistoric times, Edwards theorized.
Francois Valla, director of the French Research Center in Jerusalem and a noted archaeologist, told Discovery News that similar ancient clusters of tools have been excavated, but this latest one is "the most spectacular of them all."
"The clustering of these items is due to a decision made by some Natufian individual," Valla said. "As such, it is a rare testimony of the behavior of a person 14,000 years ago."
The toolkit's showpiece item, its double-bladed sickle, is now on display in the museum of the Faculty of Archaeology & Anthropology at Jordan's Yarmouk University.
The moon is seen above the "Feegletscher" (Fairy Glacier), near the ski resort of Saas-Fee, in Switzerland. A small group of US experts stubbornly insist that, contrary to what the vast majority of their colleagues believe, humans may not be responsible for the warming of the planet Earth.
A small group of US experts stubbornly insist that, contrary to what the vast majority of their colleagues believe, humans may not be responsible for the warming of the planet Earth.
These experts believe that global warming is a natural phenomenon, and they point to reams of data they say supports their assertions.
These conclusions are in sharp contradiction to those of the United Nations Intergovernmental Panel on Climate Change (IPCC), which reached its conclusions using largely similar data.
The UN body of about 3,000 experts, including several renown US scientists, jointly won the award with former US vice president Al Gore for their work to raise awareness about the disastrous consequences of global warming.
In mid-November the IPCC adopted a landmark report stating that the evidence of a human role in the warming of the planet was now "unequivocal."
Retreating glaciers and loss of snow in Alpine regions, thinning Arctic summer sea ice and thawing permafrost shows that climate change is already on the march, the report said.
Carbon pollution, emitted especially by the burning of oil, gas and coal, traps heat from the Sun, thus warming the Earth's surface and inflicting changes to weather systems.
A group of US scientists however disagree, and have written an article on their views that is published in The International Journal of Climatology, a publication of Britain's Royal Meteorological Society.
"The observed pattern of warming, comparing surface and atmospheric temperature trends, doesn't show the characteristic fingerprint associated with greenhouse warming," wrote lead author David Douglas, a climate expert from the University of Rochester, in New York state.
"The inescapable conclusion is that human contribution is not significant and that observed increases in carbon dioxide and other greenhouse gases make only a negligible contribution to climate warming," Douglas wrote.
According to co-author John Christi from the University of Alabama, satellite data "and independent balloon data agree that the atmospheric warming trends do not exceed those of the surface," while greenhouse models "demand that atmospheric trend values be two to three times greater."
Data from satellite observations "suggest that greenhouse models ignore negative feedback produced by clouds and by water vapor, that diminish the warming effects" of human carbon dioxide emissions.
The journal authors "have good reason, therefore, to believe that current climate models greatly overestimate the effects of greenhouse gases."
For Fred Singer, a climatologist at the University of Virginia and another co-author, the current warming "trend is simply part of a natural cycle of climate warming and cooling that has been seen in ice cores, deep sea sediments and stalagmites . . . and published in hundreds of papers in peer reviewed journals."
How these cyclical climate take place is still unknown, but they "are most likely caused by variations in the solar wind and associated magnetic fields that affect the flux of cosmic rays incident on cloudiness, and thereby control the amount of sunlight reaching the earth's surface and thus the climate."
Singer said at a recent National Press Club meeting in Washington that there is still no definite proof that humans can produce climate change.
The available data is ambiguous, Singer said: global temperatures, for example, rose between 1900 and 1940, well before humans began to burn the enormous quantities of hydrocarbons they do today. Then they dropped between 1940 and 1975, when the use of oil and coal increased, he said.
Singer believes that other factors -- like variations of solar winds and terrestrial magnetic field that impact cloud formations and the amount of sunlight reaching the Earth's surface, and thus determining the temperature -- are much more influential than human-generated greenhouse gas emissions.
Cat and mouse may never be the same. Japanese scientists say they've used genetic engineering to create mice that show no fear of felines, a development that may shed new light on mammal behavior and the nature of fear itself.
Scientists at Tokyo University say they were able to successfully switch off a mouse's instinct to cower at the smell or presence of cats — showing that fear is genetically hardwired and not learned through experience, as commonly believed.
"Mice are naturally terrified of cats, and usually panic or flee at the smell of one. But mice with certain nasal cells removed through genetic engineering didn't display any fear," said research team leader Ko Kobayakawa.
In his experiment, the genetically altered mice approached cats, even snuggled up to them and played with them. Kobayakawa said he chose domesticated cats that were docile and thus less likely to pounce.
Kobayakawa said his findings, published in the science magazine Nature last month, should help researchers shed further light on how the brain processes information about the outside world.
Kim Dae-soo, a neural genetics professor at the Korea Advanced Institute of Science and Technology in Seoul, who was not involved in the research, said Kobayakawa's research could explain further what fear is, and how to control it.
"People have thought mice are fearful of cats because cats prey on them, but that's not the case," Kim said.
"If we follow the pathway of related signals in the brain, I think we could discover what kind of networks in the brain are important for controlling fear."
Run of the Mill: Finding galactic building blocks in early universe
For more than 3 decades, astronomers have scoured the skies for tiny, ultrafaint galaxies that could be the early building blocks of the massive galaxies common in the universe today. Now researchers report that they have found 27 remote galaxies that appear to fill the bill.
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LITTLE GUYS. A glow of hydrogen gas emanates from a population of low-mass, weakly star-forming galaxies believed to be the building blocks of bright, present-day galaxies. |
These galaxies have low rates of star formation and appear to be 20 times as numerous as other, larger galaxies previously found from the same early era, when the universe was just 2 billion years old. Their properties suggest that the newly discovered bodies are part of a long-sought population of average-size galaxies that merged to form larger galaxies like the Milky Way.
Using the European Southern Observatory's Very Large Telescope (VLT) in Paranal, Chile, Michael Rauch of the Carnegie Observatories in Pasadena, Calif., and his colleagues studied a tiny patch of sky for an unprecedented 92 hours, recording extraordinarily faint levels of a particular wavelength of light. That wavelength, known as Lyman-alpha, is emitted when energetic radiation from newborn, massive stars bombards hydrogen gas within galaxies, causing the gas to glow.
As observed from Earth, the ultraviolet Lyman-alpha radiation is shifted to longer, or redder, wavelengths by the expansion of the universe. The more distant the galaxy, the greater the redshift. The redshifted Lyman-alpha radiation detected by Rauch and his colleagues indicates that the 27 galaxies reside nearly 12 billion light-years from Earth, the team will report in the March 1, 2008 Astrophysical Journal.
The weak Lyman-alpha emission indicates that these galaxies are forming stars at a sluggish rate, equaling a tenth of the sun's mass every year. In addition, the density of the galaxies found in such a small area of sky suggests that the galaxies are about 20 times as common as a well-documented collection of brighter but equally remote galaxies that make stars more prodigiously. Those galaxies, known as Lyman-break, were found using a different detection technique. They are not only rarer than the new group but also more massive, Rauch says.
Hints of the newly found building blocks for larger galaxies emerged when astronomers began studying the detailed spectra of the brilliant beacons known as quasars. The spectra revealed that as the quasar light journeyed to Earth, some of the radiation was absorbed by intervening blobs of hydrogen gas. Rauch and his collaborators now suggest that those blobs, previously revealed only as shadows on the quasar light, are the small, Lyman-alpha-emitting galaxies his team has detected.
Images of another sky region, studied intensively with the Hubble Space Telescope and known as the Hubble Ultra Deep Field, may also show signs of these run-of-the-mill galaxies, notes Rychard Bouwens of the University of California, Santa Cruz.
The 92-hour VLT study, pieced together from odd corners of the night over several years, "is a heroic observation, and I hope that it represents the start of an era rather than something the world decides is too expensive to repeat," comments David Weinberg of the Ohio State University in Columbus. Although the objects are detected at a low signal-to-noise ratio and the sample is small, the team "most likely is detecting star formation in small galaxies, mapping out the iceberg of which the previously known Lyman-break galaxies are the tip," says Weinberg. "Knowing what is going on for these more run-of-the-mill systems will be valuable for testing theories of the [early] galaxy population."
The observation bodes well for finding many more of the building blocks with ground-based telescopes, rather than having to conduct such studies in space, says Rauch.
Special Report: Managing Diabetes
More than 171 million people have this increasingly common condition. But lizard spit, new monitors and an array of other drugs and devices can help control diabetes better than ever
Diabetes has reached virtually epidemic levels in the modern world. In 2005 the U.S. Centers for Disease Control and Prevention estimated that about 7 percent of the American population (20.9 million people) had diabetes—and 6.2 million of them were unaware of it. More than 1.5 million people over the age of 20 will be diagnosed with it in the U.S. this year. About 21 percent of those older than 60 have the disease.
Small wonder, then, given the severe complications associated with diabetes, that it continues to be the sixth leading cause of death in the U.S. And although diabetes was often called a “disease of affluence” in the past, it is now one of the fastest-rising health concerns in developing nations as well: the World Health Organization pegs the global total at more than 171 million cases.
An unfortunate catch-22 of diabetes is that although the right diet and exercise can help with its prevention and management, diabetes itself can complicate both eating and physical activity. Patients may need to pay extra attention to taking meals on a regular schedule and to monitoring how exercise dehydrates them or lowers their blood glucose. Some may fail to comply consistently with prescribed regimens that seem inconvenient or unpleasant, thereby raising their risk of complications. But thanks to leaps in science’s understanding of the disease, doctors now wield a diverse and growing arsenal of drugs and management technologies to fight the progression—and even onset—of illness. People with diabetes have more and better options than ever before for enjoying healthy, active, long lives.
Background
Diabetes is a disease in which too much of a sugar called glucose accumulates in the blood because of a breakdown in how the body makes or reacts to the hormone insulin. Insulin enables muscle, fat and other types of cells to take up and process glucose. If cells can’t burn or store glucose normally and the blood levels rise chronically, damage accumulates throughout the body—in the worst cases leading to blindness, amputation, kidney failure or death.
Most cases fall into one of two categories:
Type 1 diabetes (formerly known as juvenile diabetes) occurs when the body sabotages its own ability to produce insulin. A disorder of the patient’s immune system causes it to attack the insulin-making beta cells in the pancreas. Consequently, patients with type 1 diabetes need an artificial source of insulin. Although it is the most common form of diabetes in children, only 5 to 10 percent of all cases of diabetes in the U.S. are of this variety.
Type 2 diabetes, which has become increasingly prevalent during the past few decades, arises from “insulin resistance,” which causes cells, for poorly understood reasons, to stop responding properly to the hormone. At first, the pancreas can compensate by producing greater amounts of insulin. But over time, the pancreas reduces its production, making matters worse. Initially this type of diabetes may respond to diet, exercise and weight control, but later medications, and perhaps insulin, may be necessary depending on the severity of the case.
In addition, about 4 percent of all pregnant women develop gestational diabetes, a form that usually resolves itself after delivery. Diabetes can also be a rare consequence of certain genetic conditions or chemical exposures.
Symptoms, Risk Factors and Diagnosis
More than six million Americans have type 2 diabetes and don’t know it because its early symptoms can seem so harmless and vague:
- Frequent urination
- Extreme thirst and hunger
- Irritability
- Fatigue
In contrast, type 1 diabetes comes on more quickly and with more prominent symptoms, such as unexplained rapid weight loss, dehydration or a severe illness called ketoacidosis. Medical science has still not yet determined precisely why some people develop diabetes and others do not—the genetic and environmental triggers for the disease are surprisingly complex.
For example, type 1 diabetes is not simply genetic in origin, because even the identical twin of someone with diabetes, who shares the same genes, will develop the condition no more than 50 percent of the time. Some as yet unidentified factor in the environment—perhaps a virus—must therefore trigger the immune systems of genetically susceptible people to attack the beta cells in their pancreas. Other environmental factors also seem to be involved: research finds that type 1 diabetes is less common among those who were breast-fed.
For type 2 diabetes, the genetic component is greater: it tends to run more obviously in families, and the identical twin of a person with diabetes will manifest the disease up to 75 percent of the time. Yet it is also very strongly linked to weight gain and insufficient exercise. As the American Diabetes Association (ADA) notes, “[A] family history of type 2 diabetes is one of the strongest risk factors for getting the disease, but it only seems to matter in people living a Western lifestyle.” In the U.S., type 2 diabetes is also more common among African-Americans, Latinos, Asians and Native Americans.
Two ways to diagnose diabetes definitively are testing a patient’s blood with either a fasting plasma glucose (FPG) test or an oral glucose tolerance test (OGTT). The FPG measures the concentration of glucose in the blood of a person who has been fasting for 12 hours; if it is above 125 milligrams per deciliter, the patient is diabetic. The OGTT measures the subject’s blood glucose level both after a fast and two hours after consuming a glucose-rich drink; diabetes is the diagnosis if the latter reading is above 200 milligrams per deciliter. (The ADA favors the FPG because it is less expensive, faster and easier for patients.)
Prevention and Prediabetes
People do not become diabetic overnight. Almost all of those who eventually acquire type 2 diabetes move first through a “prediabetes” state in which their blood glucose levels are elevated but not quite high enough to qualify as diabetes. (Prediabetes is also called impaired glucose tolerance and impaired fasting glucose, depending on the tests used to diagnose it.) Research suggests even those slightly less than diabetic blood glucose levels may do long-term damage to the body, and patients with prediabetes are at a 50 percent higher risk for heart disease and stroke. In a major clinical trial from 2002 called the Diabetes Prevention Program (DPP), roughly 11 percent of those with prediabetes became type 2 diabetics during the three years of the study.
The good news for the estimated 54 million Americans who have prediabetes is that many can prevent their conditions from progressing through moderate exercise and changes to diet. In fact, many of them might even be able to return their blood glucose levels to normal. The DPP found that patients who lowered their body weight by a mere 5 to 10 percent—typically just 10 to 15 pounds—through diet and moderate exercise reduced their risk of developing diabetes by 58 percent. These interventions were even more effective among patients older than 60: their risk fell by 71 percent. And it should go without saying that regular exercise and a healthy diet can help keep people from acquiring prediabetes, too.
Management and Treatment
The main goal in diabetes management is to constantly keep blood glucose levels as normal as possible. Clinical studies have shown that the rate of complications from the disease drops markedly when this standard is maintained over long periods.
But doing so is not just a matter of swallowing a pill or taking a shot. People with the condition need to steadily monitor their blood glucose levels or to anticipate changes in them and respond appropriately. To state the obvious: a sound program of diabetes management and treatment needs to be developed with a qualified health care team.
Monitoring blood glucose. All people with diabetes should periodically have a hemoglobin A1c test, which indicates the patient’s average blood glucose concentration over the preceding three months. This measurement is often the best way to see how well a treatment is going overall. Depending on his or her situation, a patient might also be monitoring daily blood glucose levels with a home blood tester. Typically this test involves pricking a finger (or palm or arm) with a trigger-style lancet, applying the drop of blood to a test strip and inserting it into a digital reader.
In a major technical advance, three companies have recently introduced continuous glucose-monitoring systems, which sample blood glucose levels many times over the course of the day with small radio-equipped sensors embedded under the skin [see “Monitoring: An End to Pricked Fingers,” below, and “Docs on Call,” below]. The systems can be programmed to sound an alarm if blood glucose goes too high or too low. Such units could eventually help revolutionize the treatment of type 1 diabetes in particular: linked to pumps for delivering insulin, they could be part of a “mechanical pancreas” that would both sense glucose in the blood and administer insulin accordingly.
Insulin. Until the 1920s, when type 1 was still the dominant form, a diagnosis of diabetes was virtually a death sentence. That all changed with the identification and isolation of insulin, which made it possible to treat the condition for the first time.
But making use of insulin began as a messy process. Running animal pancreases through a meat grinder to obtain insulin yielded a murky liquid with difficult-to-predict efficacy levels, which sometimes provoked allergic reactions. Because digestive enzymes destroy the insulin molecule, it cannot be taken orally: insulin had to be injected under the skin with a syringe. Moreover, delivering insulin in ways that most closely mimicked the body’s natural hormone action was a challenge.
Over the decades, however, every aspect of insulin therapy has improved:
Better insulins. Thanks to recombinant DNA technology, since 1982 the biotechnology industry has been able to mass-produce human insulin proteins by growing them in bacteria. Such insulin behaves more like the body’s own than animal proteins can and is less allergenic. All insulin sold in the U.S. is now of this human type.
Normally a pancreas releases small amounts of insulin into the circulation constantly, with bigger infusions at mealtimes. Most people who take insulin therefore use two types: a long-acting “basal” insulin administered once or twice a day and a rapid-acting “bolus” insulin before meals. In recent years, pharmaceutical companies have further reformulated the human insulins to create faster-, slower- and intermediate-working versions, with different durations of action, all in an attempt to re-create what the human body does.
Nicer needles. Insulin-dependent patients used to depend on large-bore needles that were relatively expensive and quickly went dull. Today’s syringes have extremely small gauge needles that can be surprisingly painless. Some insulins are packaged inside pen-shaped injectors, eliminating the need for drawing fluid out of a vial with a syringe. The pen contains many doses of insulin; new disposable needles are attached for each dosage. It makes injecting in public far more discreet.
Alternatives to injection. To most people, needle sticks are fundamentally unpleasant. So researchers have been trying to figure out easier ways to get insulin into the system. One step in that direction is the insulin pump, a pagerlike device that is worn continually and can be programmed to deliver both basal and bolus infusions through a catheter inserted under the skin. For some patients, this system is more discreet and effective than syringe injections can be. Still, pump supplies are more expensive, and care must be taken during exercise that the pump is not dislodged or damaged.
Another alternative is inhalable insulin. Pfizer introduced a version (Exubera) in 2006, but withdrew it from the market last fall, perhaps because of a somewhat unwieldy apparatus (the “insulin bong,” as some have dubbed it), the additional training required to use the device and lingering questions about long-term pulmonary effects. Other delivery methods are still under investigation, including a nasal spray, a self-contained implantable pump and a transdermal patch that uses electric current to move insulin across the skin barrier.
The ideal would be an effective oral version of insulin that could avoid destruction in the digestive tract. A number of companies are working on developing oral insulins, and Generex Biotechnology has an oral insulin spray approved for sale in Ecuador; however, similar products may be years away from proving safe and effective enough to satisfy the U.S. Food and Drug Administration.
Other Medications
Most people with diabetes do not need to take insulin, because their bodies still make some. Instead they take medications that can help them produce more insulin or use it better. Until recently, these oral meds fell into five categories: alpha glucosidase inhibitors (Precose, Glycet), metformin, meglitinides (Starlix, Prandin), sulfonylureas, and thiazolidinediones (Avandia and Actos, which have been in the headlines because of persistent concerns over their cardiovascular effects). A newer class is the DPP-4 inhibitors (Januvia is the only drug of this type available so far), which help to maintain levels of GLP-1, an intestinal hormone that promotes insulin production.
Excitement also surrounds two other new classes of drugs: incretin mimetic agents (Byetta, derived from the saliva of the Gila monster, is the only one currently on the market) and amylin analogues (Symlin is the first to be approved). Incretins are hormones that the digestive tract releases in response to carbohydrates and fats and that tell the pancreas to secrete extra insulin. Amylin is another hormone produced by the pancreas, and it helps to depress blood glucose.
Like insulin, both incretin mimetics and amylin analogues must be injected. They both have a beneficial side effect, however: they slow the emptying of the stomach. As a result, people feel full sooner, eat less and often lose weight on these drugs, which in itself can improve their diabetes.
Extreme Techniques
For some patients, dramatic measures may be called for. Gastric bypass or reduction surgery, which shrinks the space in the stomach for food, can sometimes almost eliminate type 2 diabetes in morbidly obese patients (the surgery carries its own risks, however). For a few people with type 1 diabetes, one option might be a pancreas transplant, to replace the insulin-making beta cells they have lost. But this surgery, too, can be hazardous, and few pancreases are available for transplantation. Moreover, to prevent the patient’s immune system from rejecting the new pancreas, he or she would need to take immunosuppressive drugs for life, which can also be dangerous.
A potentially safer (and less expensive) choice could someday be the experimental procedure of transplanting just the pancreatic islet clusters that contain the beta cells. Such implants would involve less trauma than replacing an entire pancreas, and it might be possible to encase the grafted cells in packaging that would protect them from the immune system. Researchers are also working on using highly versatile stem cells, which can give rise to new tissues, to replace lost beta cells. The early results are guardedly positive, but it will be years, if ever, before such a technique becomes widely available.
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