At the annual meeting of the American Geophysical Union, geologists proposed that Mesopotamian societal decline was due, at least in part, to increased aridity for two to three centuries. “This was not a single summer or winter, this was 200 to 300 years of drought,” said Matt Konfirst of the Byrd Polar Research Center. “As we go into the 4,200-year-ago climate anomaly, we actually see that estimated rainfall decreases substantially in this region and the number of sites that are populated at this time period reduce substantially… People still live in this region. It’s not that the collapse of a civilization means that an area is completely abandoned, but that there’s a sharp change in the population.”
A team of researchers has proposed that climate shifts triggered societal stress about 5500 years ago in northwest Australia. Severe aridification “seems to coincide with the collapse of one culture until the climate adjusted to a level similar to what we see today and another took its place,” said Hamish McGowan of the University of Queensland. “Our research shows that the likely reason for the demise of the Gwion artists was a mega-drought spanning approximately 1500 years, brought on by changing climate conditions that caused the collapse of the Australian summer monsoon… This is contrary to the conventional view that Australian Aboriginals lived a highly sustainable hunter-gatherer existence in which their knowledge of the landscape meant they adapted to climate variability with little impact.”
Evidence from a Severn Estuary archaeological site in Great Britain — flint tools, bones, charcoal, hazelnut shells, insects, pollen, and more — reveals how Mesolithic people manipulated the environment to meet their needs. “Previously it was thought that these people were mainly hunting deer and simply responding to the spectacular environmental changes around them, such as sea level rise,” said Professor Martin Bell of the University of Reading. “Now there is increasing evidence that they were adept at manipulating their environment to increase valued plant resources. Combining our finds with the trees, pollen and insects from the area we can build a picture of the environmental relationships of Mesolithic hunter-gatherers. These people were highly adaptable and continued using the same site as the environment changed dramatically from old woodland to reedswamp, to saltmarsh and back to fen woodland.”
New research offers soil evidence that at least one of the massive earthworks at Poverty Point in Louisiana was constructed in less than 90 days, possibly much faster. “What’s extraordinary about these findings is that it provides some of the first evidence that early American hunter-gatherers were not as simplistic as we’ve tended to imagine,” said T.R. Kidder of Washington University in St. Louis. “Our findings go against what has long been considered the academic consensus on hunter-gather societies—that they lack the political organization necessary to bring together so many people to complete a labor-intensive project in such a short period.” Core samples and sedimentary analysis suggests that Mound A at Poverty Point was built in a very short period due to no signs of rainfall or erosion during its construction.“We’re talking about an area of northern Louisiana that now tends to receive a great deal of rainfall,” explained Kidder. “Even in a very dry year, it would seem very unlikely that this location could go more than 90 days without experiencing some significant level of rainfall. Yet, the soil in these mounds shows no sign of erosion taking place during the construction period. There is no evidence from the region of an epic drought at this time either.”
Today a meteor landed in the Russian Urals, and an asteroid will pass within 28,000 km (18,000 miles) of Earth. The latest research into the proposed “Clovis impact event,” however, refutes a hypothesis that comet explosions changed Earth’s climate and ended the Clovis culture in North America around 13,000 years ago. “There’s no plausible mechanism to get airbursts over an entire continent,” said Sandia National Laboratories physicist Mark Boslough. “For this and other reasons, we conclude that the impact hypothesis is, unfortunately, bogus.” The researchers also showed that samples used to support of the impact event were contaminated with contemporary material. “The theory has reached zombie status,” said Professor Andrew Scott at Royal Holloway, University of London. “Whenever we are able to show flaws and think it is dead, it reappears with new, equally unsatisfactory, arguments.” Boslough added, “Just because a culture changed from Clovis to Folsom spear points didn’t mean their civilization collapsed. They probably just used another technology. It’s like saying the phonograph culture collapsed and was replaced by the iPod culture.”
Using isotopic signals in cave stalagmites, a team of archaeologists and earth scientists has assembled a high-resolution climate record, spanning two millennia, and it suggests that Maya political systems may have developed and disintegrated in response to climate changes. ”Unusually high amounts of rainfall favored an increase in food production and an explosion in the population between AD 450 and 660,” said Douglas Kennett of Penn State. “This led to the proliferation of cities like Tikal, Copan and Caracol across the Maya lowlands. The new climate data show that this salubrious period was followed by a general drying trend lasting four centuries that was punctuated by a series of major droughts that triggered a decline in agricultural productivity and contributed to societal fragmentation and political collapse.” Given the rich archaeological and historical records of the Maya, there is an opportunity to explore the long-term effects of climate change for both the development and disintegration of complex sociopolitical systems. ”The effects of climate change are complex and play out over multiple time scales,” said Kennett. “Abrupt climate change is only part of the story. In addition to climate drying and drought, the preceding conditions stimulating societal complexity and population expansion helped set the stage for later stress on their societies.”
My newest paper in the Journal of Archaeological Sciences made it into the archaeology news cycle, and here are some of the websites where it has been featured:
The stones in ancient Maori ovens are providing researchers with new information about Earth’s magnetic field in a part of the world where it is poorly understood. Under the intense heat of the cooking fires, the magnetic minerals in the stones were heated above their Curie temperatures and demagnetised. As the stones cooled down, those minerals become magnetised with the direction and strength of Earth’s field. ”We have very good palaeomagnetic data from across the world recording field strength and direction, especially in the Northern Hemisphere,” said Gillian Turner from Victoria University. ”The southwest Pacific is the gap, and in order to complete global models, we’re rather desperate for good, high-resolved data from our part of the world.”
In the early 1900s, archaeologist William Mills concluded that stone pipes from Tremper Mound in southern Ohio were carved from local stone. He published that conclusion in 1916, and it has been repeated in literature many times since. Based on new analyses, however, researchers have determined that the raw material — and perhaps even the finished pipes — primarily originated elsewhere in the American Midwest: Illinois and Minnesota. Less than 20 percent of 111 Tremper Mound pipes were crafted from local Ohio stone. About 65 percent, however, were fashioned from a clay known only in northern Illinois, and 18 percent were made of catlinite from Minnesota. ”This study really says to the archaeological community, you need to go back to the drawing board,” said the lead author Thomas Emerson. “You’ve been telling stories for decades that are based on essentially misinformation.” Emerson also notes that these findings demonstrate that the Hopewell people of Ohio seemed to be “conspicuous consumers and connoisseurs of the exotic… Strange animals, strange minerals, strange things were really a focus.”
Neolithic farming communities in Germany built water wells out of oak timbers about 7000 years ago. How these early famers lived remains largely unknown, including the climate in which they lived and technologies or strategies that they used to cope with their environment. These oak timbers are provide a new source of environmental data preserved within the tree rings, which could offer a year-by-year record of the climate in which these early agriculturalists lived.
An international team of archaeologists has generated new insights into water management and intensive agriculture around Petra in the Jordanian desert. With high-resolution satellite imagery and optically stimulated luminescence (OSL) dating, researchers have proposed that terraced farming and dam construction began about two millennia ago, not during the earlier Iron Age (circa 1200-300 BC), as previously hypothesised. Terrace farming of wheat, grapes, and perhaps olives produced in a vast agricultural “suburb” of Petra in an otherwise arid landscape. Such extensive landscape modification and water management can offer insights into geopolitical changes and Roman imperialism at Petra.
About 74,000 years ago, the eruption of Indonesia’s Toba supervolcano was five thousand times larger than Mount St. Helens in 1980. The extent and severity of the volcanic effects on humanity have been highly debated. On one hand, researchers have concluded that the eruption triggered a millennium-long ice age that with only 10,000 survivors. On the other hand, archaeological evidence suggests that humans were thriving in India shortly after the eruption. A new study, based on Antarctica and Greenland ice cores, indicates that the effects were not so catastrophic. ”That means there’s no long-term global cooling caused by the eruption,” said Anders Svensson of the Niels Bohr Institute’s Centre for Ice and Climate. ”There may have been shorter [global] cooling of a duration of maybe 10 or 20 years… certainly not causing long-term cooling of a thousand years, or even a hundred. It seems like humans lived on and everything is recovering.”
Research published In the Soil Science Society of America Journal investigates maize agriculture at Tikal based on its soils. As expected, the interdisciplinary team discovered evidence for considerable maize production in lowland areas, where erosion is minor and, in turn, agriculture was fairly sustainable for an estimated population of 60,000 at Tikal. These researchers, however, also found indications that farming eventually spread to steeper, less suitable slopes. The team concludes that, if Maya agriculture did cause marked erosion, soil loss may have undercut their capacity to produce enough food.
The above painting, Pacini’s “The Last Day of Pompeii” (circa 1830), depicts the eruption of Mount Vesuvius that destroyed the Roman city in 79 CE. At the Rosetta Stones blog, Dana Hunter details what volcanically occurred that day, from the initial phreatomagmatic phase to the final deadly pyroclastic flow.