Rutgers University

SCIENTISTS DISCOVER WORLD’S OLDEST STONE TOOLS

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Sonia Harmand and Jason Lewis examine stone artifacts at the Lomekwi dig in Kenya. Photo credit: West Turkana Archaeological Project

Scientists working in the desert badlands of northwestern Kenya have found stone tools dating back 3.3 million years, long before the advent of modern humans, and by far the oldest such artifacts yet discovered.

The tools, whose makers may or may not have been some sort of human ancestor, push the known date of such tools back by 700,000 years; they also may challenge the notion that our own most direct ancestors were the first to bang two rocks together to create a new technology.

The discovery is the first evidence that an even earlier group of proto-humans may have had the thinking abilities needed to figure out how to make sharp-edged tools. The stone tools mark “a new beginning to the known archaeological record,” say the authors of a new paper about the discovery, published today in the leading scientific journal Nature.

“The whole site’s surprising, it just rewrites the book on a lot of things that we thought were true,” said geologist Chris Lepre of the Lamont-Doherty Earth Observatory and Rutgers University, a co-author of the paper who precisely dated the artifacts. The tools “shed light on an unexpected and previously unknown period of hominin behavior and can tell us a lot about cognitive development in our ancestors that we can’t understand from fossils alone,” said lead author Sonia Harmand, of the Turkana Basin Institute at Stony Brook University and the Université Paris Ouest Nanterre.

Hominins are a group of species that includes modern humans, Homo sapiens , and our closest evolutionary ancestors. Anthropologists long thought that our relatives in the genus Homo—the line leading directly to Homo sapiens—were the first to craft such stone tools. But researchers have been uncovering tantalizing clues that some other, earlier species of hominin, distant cousins, if you will, might have figured it out.

The researchers do not know who made these oldest of tools. But earlier finds suggest a possible answer: The skull of a 3.3-million-year-old hominin, Kenyanthropus platytops, was found in 1999 about a kilometer from the tool site. A K. platyops tooth and a bone from a skull were discovered a few hundred meters away, and an as-yet unidentified tooth has been found about 100 meters away.

Chris Lepre from Lamont-Doherty Earth Observatory takes sediment samples to help date the age of the Lomekwi site. Photo credit: West Turkana Archaeological Project

The precise family tree of modern humans is contentious, and so far, no one knows exactly howK. platyops relates to other hominin species.Kenyanthropus predates the earliest knownHomospecies by a half a million years. This species could have made the tools; or, the toolmaker could have been some other species from the same era, such as Australopithecus afarensis, or an as-yet undiscovered early type of Homo.

Lepre said a layer of volcanic ash below the tool site set a “floor” on the site’s age: It matched ash elsewhere that had been dated to about 3.3 million years ago, based on the ratio of argon isotopes in the material. To more sharply define the time period of the tools, Lepre and co-author and Lamont-Doherty colleague Dennis Kent examined magnetic minerals beneath, around and above the spots where the tools were found.

The Earth’s magnetic field periodically reverses itself, and the chronology of those changes is well documented going back millions of years. “We essentially have a magnetic tape recorder that records the magnetic field … the music of the outer core,” Kent said. By tracing the variations in the polarity of the samples, they dated the site to 3.33 million to 3.11 million years.

Another co-author, Rhonda Quinn of Seton Hall University, studied carbon isotopes in the soil, which along with animal fossils at the site allowed researchers to reconstruct the area’s vegetation. This led to another surprise: The area was at that time a partially wooded, shrubby environment. Conventional thinking has been that sophisticated tool-making came in response to a change in climate that led to the spread of broad savannah grasslands, and the consequent evolution of large groups of animals that could serve as a source of food for human ancestors.

One line of thinking is that hominins started knapping—banging one rock against another to make sharp-edged stones—so they could cut meat off of animal carcasses, said paper co-author Jason Lewis of the Turkana Basin Institute and Rutgers. But the size and markings of the newly discovered tools “suggest they were doing something different as well, especially if they were in a more wooded environment with access to various plant resources,” Lewis said. The researchers think the tools could have been used for breaking open nuts or tubers, bashing open dead logs to get at insects inside, or maybe something not yet thought of.

The Lomekwi 3 dig sits in arid lands west of Lake Turkana in northwest Kenya. Photo credit: West Turkana Archaeological Project

“The capabilities of our ancestors and the environmental forces leading to early stone technology are a great scientific mystery,” said Richard Potts , director of the Human Origins Program at the Smithsonian’s National Museum of Natural History, who was not involved in the research. The newly dated tools “begin to lift the veil on that mystery, at an earlier time than expected,” he said. Potts said he had examined the stone tools during a visit to Kenya in February.

“Researchers have thought there must be some way of flaking stone that preceded the simplest tools known until now,” he said. “Harmand’s team shows us just what this even simpler altering of rocks looked like before technology became a fundamental part of early human behavior.”

Ancient stone artifacts from East Africa were first uncovered at Olduvai Gorge in Tanzania in the mid-20th century, and those tools were later associated with fossil discoveries in the 1960s of the early human ancestor Homo habilis. That species has been dated to 2.1 million to 1.5 million years ago.

Subsequent finds have pushed back the dates of humans’ evolutionary ancestors, and of stone tools, raising questions about who first made that cognitive leap. The discovery of a partial lower jaw in the Afar region of Ethiopia, announced on March 4, pushes the fossil record for the genusHomo to 2.8 million years ago. Evidence from recent papers, the authors note, suggests that there is anatomical evidence thatHomo had evolved into several distinct lines by 2 million years ago.

Photos of selected Lomekwi 3 stones accompanying the paper show both cores and flakes knapped from the cores that the authors say illustrate various techniques.

There is some evidence of more primitive tool use going back even before the new find. In 2009, researchers at Dikika, Ethiopia, dug up 3.39 million-year-old animal bones marked with slashes and other cut marks, evidence that someone used stones to trim flesh from bone and perhaps crush bones to get at the marrow inside. That is the earliest evidence of meat and marrow consumption by hominins . No tools were found at the site, so it’s unclear whether the marks were made with crafted tools or simply sharp-edged stones. The only hominin fossil remains in the area dating to that time are fromAustralopithecus afarensis.

The new find came about almost by accident: Harmand and Lewis said that on the morning of July 9, 2011, they had wandered off on the wrong path, and climbed a hill to scout a fresh route back to their intended track. They wrote that they “could feel that something was special about this particular place.” They fanned out and surveyed a nearby patch of craggy outcrops. “By teatime,” they wrote, “local Turkana tribesman Sammy Lokorodi had helped [us] spot what [we] had come searching for.”

By the end of the 2012 field season, excavations at the site, named Lomekwi 3, had uncovered 149 stone artifacts tied to tool-making, from stone cores and flakes to rocks used for hammering and others possibly used as anvils to strike on.

The researchers tried knapping stones themselves to better understand how the tools they found might have been made. They concluded that the techniques used “could represent a technological stage between a hypothetical pounding-oriented stone tool use by an earlier hominin and the flaking-oriented knapping behavior of [later] toolmakers.” Chimpanzees and other primates are known to use a stone to hammer open nuts atop another stone. But using a stone for multiple purposes, and using one to crack apart another into a sharper tool, is more advanced behavior.

The find also has implications for understanding the evolution of the human brain. The toolmaking required a level of hand motor control that suggests that changes in the brain and spinal tract needed for such activity could have occurred before 3.3 million years ago, the authors said.

“This is a momentous and well-researched discovery,” said paleoanthropologist Bernard Woodof George Washington University, who was not involved in the study. “I have seen some of these artifacts in the flesh, and I am convinced they were fashioned deliberately.” Wood said he found it intriguing to see how different the tools are from so-called Oldowan stone tools, which up to now have been considered the oldest and most primitive.

Lepre, who has been conducting fieldwork in eastern Africa for about 15 years, said he arrived at the dig site about a week after the discovery. The site is several hours’ drive on rough roads from the nearest town, located in a hot, dry landscape he said is reminiscent of Arizona and New Mexico. Lepre collected chunks of sediment from a series of depths and brought them back to Lamont-Doherty for analysis. He and Kent used a bandsaw to trim the samples into sugar cube-size blocks and inserted them into a magnetometer, which measured the polarity of tiny grains of the minerals hematite and magnetite contained in the sediment.

“The magnetics pretty much clinches that the age is something like 3.3 million years old,” said Kent, who also is a professor at Rutgers.

Earlier dating work by Lepre and Kent helped lead to another landmark paper in 2011 : a study that suggested Homo erectus , another precursor to modern humans, was using more advanced tool-making methods 1.8 million years ago, at least 300,000 years earlier than previously thought.

Vapours from damp buildings may trigger Parkinson’s

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A vapour known as “mushroom alcohol” which is present in damp, mouldy buildings can damage the nerve cells of the brain responsible for Parkinson’s disease, scientists said.

A study has found that the compound, called 1-octen-3-ol, leads to the degeneration of two genes involved with the transport and storage of dopamine, the neurotransmitter in the brain that is lost in patients with Parkinson’s.

The researchers suggest that the volatile substances given off by mildew and other fungi growing in damp houses may be a significant risk factor in the development of the degenerative brain disease, which is thought to have environmental as well as genetic causes.

The study was carried out on the dopamine system of fruit flies, a recognised animal “model” of Parkinson’s disease, and the researchers calculated that mushroom alcohol was more toxic to these specialised nerves than benzene – a poisonous chemical known to cause genetic damage.

“These findings are of particular interest given recent epidemiological studies that have raised the concern of neuropsychological impairments and movement disorders in human populations exposed to mouldy and water-damaged buildings,” the scientists said in the study published in the journal Proceedings of the National Academy of Sciences. “Increased incidence of Parkinson’s disease is seen in rural populations, where it is usually attributed to pesticide exposure. However, the prevalence of mould and mushroom in these environments may provide another plausible risk factor for the development of Parkinson’s disease.”

Until recently, the search for environmental factors that could trigger the disease has focused largely on man-made chemicals, such as pesticides. However, natural compounds could be equally to blame, said Arati Inamdar of Rutgers University.

“There have been studies indicating that Parkinson’s disease is increasing in rural areas, where it’s usually attributed to pesticide exposure. But rural environments also have a lot of exposure to moulds and other fungi, and our work suggests that 1-octen-3-ol might also be connected to the disease, particularly for people with a genetic susceptibility to it,” she added.

Joan Bennett, co-author of the study, said she took an interest in the role of fungi in health after she became ill working in her flood-damaged house in New Orleans after Hurricane Katrina in 2005.

“I knew something about ‘sick building’ syndrome, because I am an expert in toxic fungi. I didn’t believe in it, because I didn’t think it would be possible to breathe in enough mould spores to get sick,” Professor Bennett said.

But when collecting samples while wearing protective gear, she fell ill. “While I was doing the sampling, I felt horrible – headaches, dizziness and nausea. I had a conversion experience,” she said.

Claire Bale, a spokesperson for Parkinson’s UK, said that the cause of Parkinson’s disease is one of the big unanswered questions.

“We already know that exposure to some chemicals can slightly increase the risk of Parkinson’s, and this is the first study to suggest that chemicals produced by fungi may play a part,” Ms Bale said.

“It is important to remember, this study was conducted using tiny fruit flies, so before we can really be confident about this new connection we need to see evidence from studies in people,” she added.

Food production and obesity linked to climate change.

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Horse meat sold as beef has made headlines and provoked consumer outrage in the UK, but the contribution of global food production—and particularly meat—to climate change is the larger scandal, according to experts who spoke to The Lancet Respiratory Medicine.

“Meat and dairy are a hotspot for ecological public health”, notes Timothy Lang (Centre for Food Policy, City University London, London, UK). “About half the world’s grain is fed to animals. The land and water use for such production systems are enormous. But this has created a situation where supposedly efficient modern agricultural systems have turned domestic animals as sources of cheap meat into direct competitors with humans for dominance in the ecological space.”

Although many people understand the threats that are posed to food systems by rising temperatures, extreme weather, and changing precipitation patterns, few seem to appreciate the degree to which human food production contributes to global climate change and the resulting health risks.

“It is bizarre that so many people in public health seem barely aware of food’s massive contribution to climate change”, remarks Lang. “This is not just unfortunate but downright irresponsible.”

An estimated 14% of greenhouse gas emissions come directly from agriculture (putting it on par with transportation emissions). Increasing transportation distances to market worsens food’s carbon footprint—a factor for which Lang coined the term “food miles.”

“A policy shift toward horticulture rather than animal-oriented agriculture is long overdue and is set to be a key challenge for the 21st century”, Lang believes. Public education campaigns to encourage people to eat less meat would seem to be the obvious direction for public health and environmental interventions meant to mitigate climate change. But public education is more easily advocated than implemented.

“In the past few years, several attempts to generate sustainable dietary advice for populations have come up against some big food-industry vested interests”, Lang says, citing recent controversies in Sweden, the UK, and Australia over proposed consumer advisories and nutritional guidelines. “Powerful interests will fight hard not to address the challenge of sustainability.”

Food production and agricultural and trade policies have been hijacked by a small number of large corporations in recent decades, agrees Wenonah Hauter (Food & Water Watch, Washington, DC, USA), whose father fled Oklahoma in the 1930s because of the so-called Dust Bowl—severe dust storms largely driven by agriculture.

In the USA, “20 large food processors own most brands on retail shelves”, notes Hauter. “Our political system is set up to allow companies to become larger and larger. During the Reagan administration, antitrust law was one of the main targets of the deregulatory agenda. They cut staff and enforcement budgets at regulatory agencies, and narrowed the definition of what constitutes an antitrust violation. Predictably, these companies became so large they’re able to dictate food and farm policy on everything from what pesticides we’re exposed to, to the way that food is made and labelled.”

US agriculture policy was further deregulated under the Clinton administration in the mid 1990s “to get in line with trade policy”, Hauter says. Deregulation of grain commodities during the 1990s saw increased corporate consolidation of corporate meat production, with the “factory farms” proportion of pork production, for example, rising from 30% in 1995 to 95% by 2005.

Under President Obama, efforts to curb junk food advertisements aimed at children yielded only “very weak voluntary guidelines”, Hauter says, which is testament to food industry lobbyists’ sway in Washington DC.

“Governments don’t govern; they follow”, cautions Lang. “Too often they are timid with regard to health and environment. The neoliberal perspective dominates: leave it to the consumer. But consumers are in the dark about the impact their food has on the planet, and the avalanche of cheap calories [in developed countries] acts as the model for what consumerism aspires to. But increasingly, scientists are aware that we need a new direction for food. We have to link human and environmental health.”

The interactions between abundant cheap calories, obesity, and the environment can generate complex feedback loops between climate, food, and epidemiology. The industrial production and global transportation of food contributes to global climate change, which affects agriculture through changes in precipitation and temperature, and extreme weather events. The effects will be felt unevenly around the planet, further impoverishing Africa’s agricultural base, for example. Overweight and obese people consume more food than others and rely disproportionately on travel by car, which together increases their carbon footprint to make obesity itself a serious global environmental problem, according to a 2009 study by scientists at the London School of Hygiene & Tropical Medicine.

The burden of respiratory disease is expected to increase with global temperatures, and the link between respiratory disorders, such as asthma and sleep apnoea, could be compounded by the environmental consequences of climate change. Extreme heat, air pollutants such as ozone and particulate matter, and increased production of plant and fungal allergens, will all conspire to drive up respiratory morbidity and mortality rates.

Early modelling studies predict that concentrations of pollen from common tree species such as oak and birch, and weeds such as the highly-allergenic ragweed, will increase by 20—30% by 2020, and will continue climbing for decades to follow, notes Leonard Bielory (Center for Environmental Prediction, Rutgers University, Springfield, NJ, USA). The US Environmental Protection Agency is funding research at Rutgers University to assess the effect of climate change on allergenic airway disease, says Bielory.

Respiratory syncytial virus infections are more common when temperatures are higher. Prolonged drought and increased airborne levels of particulate matter from wildfire smoke and dust—including the intercontinental movement of dust from growing expanses of African desert—are expected to exacerbate asthma and COPD symptoms.

Concentrations of ground-level ozone, a highly oxidative air pollutant, are expected to rise in some regions and drop in others, leading to increased rates of respiratory distress, exacerbated airway diseases such as asthma, and respiratory infection risks, adds Hans Orru (Department of Public Health, University of Tartu, Estonia). Predicted increases in ground-level ozone will hit central and southern Europe harder than northern Europe, which is likely to see declines in ozone, Orru says.

“There are a number of interactions between plant biology, which will certainly be affected by rising CO2 and increased temperature, and public health concerns. These interactions can run the gamut from aeroallergens to nutrition to pesticide use”, says Lewis H Ziska (Crop Systems and Global Change Laboratory, US Department of Agriculture, Beltsville, MD, USA). “There is initial evidence that all of these issues are already being affected.”

Recent and projected changes in atmospheric CO2 have been shown to change yields of plant food proteins, antioxidants, and omega-3 fatty acids, Ziska points out. “One key question we have is whether or not rising CO2 will also affect food allergies.” Ragweed pollen season has increased by as much as 13—27 days at higher latitudes since 1995, according to a 2011 study by Ziska, Bielory, and colleagues. Increased pollen seasons correspond to an increased number of frost-free days, Bielory notes.

Another key question is whether or not plant pollen might become more allergenic with changing temperatures or CO2 levels. The effects of air pollutants on respiratory health can be compounded by the presence of respiratory allergens, Ziska notes. Pollen sticks to larger particulate matter associated, for example, with diesel fumes. “The particulate matter can act as a platform that attracts pollen and drives it further into the lungs”, Ziska explains. Sensitisation to common seasonal allergens has doubled over the past 20 years along with symptoms, Bielory has found.

In addition to airborne allergens, the effect of climate change on plant communities might lead to larger populations of disease vectors such as mosquitoes, whose larvae can feed on pollen.

AJ McMichael (National Centre for Epidemiology and Population Health, Australian National University, ACT, Australia) and others believe that major civilisational shifts, resulting in starvation, warfare, migration, and revolution, have accompanied abrupt climatic change in the past. A recent report even links droughts in wheat-producing regions of the globe with the Arab Spring uprisings in countries that are among the largest wheat importers.

Climate change will unveil complex interactions between plants and human physiology, Ziska concludes. “We are getting a sense of what some of those interactions are, and how significant they are, but we have a great deal more yet to do”. Untangling these interactions will be a major interdisciplinary endeavour.

Source: lancet