Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Closing the Case on an Ancient Archeological Mystery

29.04.2015

Solving 4,000-year-old mystery helps WSU archeologist find useful resource for a warmer future

Climate change may be responsible for the abrupt collapse of civilization on the fringes of the Tibetan Plateau around 2000 B.C.


Barley cultivation in Jiuzhaigou National Park hasn't changed much in nearly 2,000 years. The park is located in the Min Shan mountain range, Northern Sichuan in South Western China.

Credit: Washington State University

WSU archaeologist Jade D'Alpoim Guedes and an international team of researchers found that cooling global temperatures at the end of the Holocene Climatic Optimum, a 4,000 year period of warm weather, would have made it impossible for ancient people on the Tibetan Plateau to cultivate millet, their primary food source.

Guedes' team's research recently was published online in the Proceedings of the National Academy of Sciences. Her results provide the first convincing explanation for why the area's original inhabitants either left or so abruptly changed their lifestyles.

They also help explain the success of farmers who practiced wheat and barley agriculture in the region 300 years later.

Unlike millet, wheat and barley have high frost tolerance and a low heat requirement, making them ideally suited for the high altitudes and cold weather of eastern Tibet. Guedes argues this made the two crops an important facet of subsistence immediately after their introduction around 1700 B.C.

"Wheat and barley came in at the opportune moment, right when millets were losing their ability to be grown on the Tibetan Plateau," Guedes said. "It was a really exciting pattern to notice. The introduction of wheat and barley really enabled Tibetan culture to take the form it has today, and their unique growth patterns may have played a crucial rule in the spread of these crops as staples across the vast region of East Asia."

One offshoot of the research: The ancient millet seeds that fell out of cultivation on the Tibetan Plateau as the climate got colder might soon be useful again as the climate warms up.

"Right now, these millets have almost become forgotten crops," Guedes said. "But due to their heat tolerance and high nutritional value, they may be once again be useful resources for a warmer future."

An archaeological enigma

At Ashaonao, Haimenkou, and other archeological sites in the Tibetan highlands, researchers for years had noticed a growing trend. An abundance of ancient wheat and barley seeds found at the sites suggested the crops rapidly replaced millet as the staple food source of the region during the second millennium BCE.

The findings were puzzling considering that the scientific consensus of the time was the region's climate would have actually favored millet, due to its shorter growing season, over wheat or barley.

The conundrum intrigued Guedes so she dove into the agronomy literature to investigate. She found agronomists tended to use a different measurement than archaeologists to determine whether crops can grow in cold, high altitude environments like the Tibetan Plateau. They used total growing degree days or the accumulated amount of heat plants need over their lifetime rather than the length of a growing season.

"My colleagues and I created a new model based off what we found in the literature," Guedes said. "It revealed that global cooling would have made it impossible to grow millet in the Eastern Tibetan Highlands at this time but would have been amenable to growing wheat and barley. Our work turned over previous assumptions and explained why millet is no longer a staple crop in the area after 2000 BCE."

Guedes' work points to climate cooling as the culprit behind the collapse of early civilization on the Tibetan Plateau. Ironically, the region is today one of the areas experiencing the most rapid climate warming on the planet. There are some areas in the southeastern plateau where temperatures are 6 degrees Celsius higher than they were 200 years ago.

Rapid temperature increase is making it difficult for the region's inhabitants to raise and breed yaks, a staple form of subsistence in the central Asian highlands, and grow cold weather crops, once again endangering their survival.

"So now we have a complete reversal and climate warming is having a big impact on the livelihood of smaller farmers on the Tibetan Plateau," Guedes said.

Media Contact

Jade D'Alpoim Guedes
jade.dalpoimguedes@wsu.edu
509-335-2304

 @WSUNews

http://www.wsu.edu 

Jade D'Alpoim Guedes | EurekAlert!

Further reports about: Mystery Tibetan barley climate warming crops food source growing season temperatures

More articles from Earth Sciences:

nachricht Early organic carbon got deep burial in mantle
25.04.2017 | Rice University

nachricht New atlas provides highest-resolution imagery of the Polar Regions seafloor
25.04.2017 | British Antarctic Survey

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Early organic carbon got deep burial in mantle

25.04.2017 | Earth Sciences

A room with a view - or how cultural differences matter in room size perception

25.04.2017 | Life Sciences

Warm winds: New insight into what weakens Antarctic ice shelves

25.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>