The heat is on: Traces of fire uncovered dating back at least 800,000 years

Log Fire

They say that where there's smoke, there's fire, and Weizmann Institute of Science researchers are working hard to investigate that claim, or at least elucidate what constitutes "smoke." In an article published today in PNAS, the scientists reveal an advanced, innovative method that they have developed and used to detect nonvisual traces of fire dating back at least 800,000 years -- one of the earliest known pieces of evidence for the use of fire. The newly developed technique may provide a push toward a more scientific, data-driven type of archaeology, but -- perhaps more importantly -- it could help us better understand the origins of the human story, our most basic traditions and our experimental and innovative nature.

The controlled use of fire by ancient hominins -- a group that includes humans and some of our extinct family members -- is hypothesized to date back at least a million years, to around the time that archaeologists believe Homo habilis began its transition to Homo erectus. That is no coincidence, as the working theory, called the "cooking hypothesis," is that the use of fire was instrumental in our evolution, not only for allowing hominins to stay warm, craft advanced tools and ward off predators but also for acquiring the ability to cook. Cooking meat not only eliminates pathogens but increases efficient protein digestion and nutritional value, paving the way for the growth of the brain. The only problem with this hypothesis is a lack of data: since finding archaeological evidence of pyrotechnology primarily relies on visual identification of modifications resulting from the combustion of objects (mainly, a color change), traditional methods have managed to find widespread evidence of fire use no older than 200,000 years. While there is some evidence of fire dating back to 500,000 years ago, it remains sparse, with only five archaeological sites around the world providing reliable evidence of ancient fire.

"We may have just found the sixth site," says Dr. Filipe Natalio of Weizmann's Plant and Environmental Sciences Department, whose previous collaboration with Dr. Ido Azuri, of Weizmann's Life Core Facilities Department, and colleagues provided the basis for this project. Together they pioneered the application of AI and spectroscopy in archaeology to find indications of controlled burning of stone tools dating back to between 200,000 and 420,000 years ago in Israel. Now they're back, joined by PhD student Zane Stepka, Dr. Liora Kolska Horwitz from the Hebrew University of Jerusalem and Prof. Michael Chazan from the University of Toronto, Canada. The team upped the ante by taking a "fishing expedition" -- casting far out into the water and seeing what they could reel back in. "When we started this project," says Natalio, "the archaeologists who've been analyzing the findings from Evron Quarry told us we wouldn't find anything. We should have made a bet."

Evron Quarry, located in the Western Galilee, is an open-air archaeological site that was first discovered in the mid-1970s. During a series of excavations that took place at that time and were led by Prof. Avraham Ronen, archaeologists dug down 14 meters and uncovered a large array of animal fossils and Paleolithic tools dating back to between 800,000 and 1 million years ago, making it one of the oldest sites in Israel. None of the finds from the site or the soil in which they were found had any visual evidence of heat: ash and charcoal degrade over time, eliminating the chances of finding visual evidence of burning. Thus, if the Weizmann scientists wanted to find evidence of fire, they had to search farther afield.

The "fishing" expedition began with the development of a more advanced AI model than they had previously used. "We tested a variety of methods, among them traditional data analysis methods, machine learning modeling and more advanced deep learning models," says Azuri, who headed the development of the models. "The deep learning models that prevailed had a specific architecture that outperformed the others and successfully gave us the confidence we needed to further use this tool in an archaeological context having no visual signs of fire use." The advantage of AI is that it can find hidden patterns across a multitude of scales. By pinpointing the chemical composition of materials down to the molecular level, the output of the model can estimate the temperature to which the stone tools were heated, ultimately providing information about past human behaviors.

With an accurate AI method in hand, the team could start fishing for molecular signals from the stone tools used by the inhabitants of the Evron Quarry almost a million years ago. To this end, the team assessed the heat exposure of 26 flint tools found at the site almost half a century ago. The results revealed that the tools had been heated to a wide range of temperatures -- some exceeding 600°C. In addition, using a different spectroscopic technique, they analyzed 87 faunal remains and discovered that the tusk of an extinct elephant also exhibited structural changes resulting from heating. While cautious in their claim, the presence of hidden heat suggests that our ancient ancestors, not unlike the scientists themselves, were experimentalists.

According to the research team, by looking at the archaeology from a different perspective, using new tools, we may find much more than we initially thought. The methods they've developed could be applied, for example, at other Lower Paleolithic sites to identify nonvisual evidence of fire use. Furthermore, this method could perhaps offer a renewed spatiotemporal perspective on the origins and controlled use of fire, helping us to better understand how hominin's pyrotechnology-related behaviors evolved and drove other behaviors. "Especially in the case of early fire," says Stepka, "if we use this method at archaeological sites that are one or two million years old, we might learn something new."

By all accounts, the fishing expedition was a resounding success. "It was not only a demonstration of exploration and being rewarded in terms of the knowledge gained," says Natalio, "but of the potential that lies in combining different disciplines: Ido has a background in quantum chemistry, Zane is a scientific archaeologist, and Liora and Michael are prehistorians. By working together, we have learned from each other. For me, it's a demonstration of how scientific research across the humanities and science should work."

Story Source- Science Daily

 

Origins of the Black Death identified

Yersinia pestis illustration

The Black Death, the biggest pandemic of our history, was caused by the bacterium Yersinia pestis and lasted in Europe between the years 1346 and 1353. Despite the pandemic's immense demographic and societal impacts, its origins have long been elusive. Now, a multidisciplinary team of scientists, including researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, the University of Tübingen, in Germany, and the University of Stirling, in the United Kingdom, have obtained and studied ancient Y. pestis genomes that trace the pandemic's origins to Central Asia.

In 1347, plague first entered the Mediterranean via trade ships transporting goods from the territories of the Golden Horde in the Black Sea. The disease then disseminated across Europe, the Middle East and northern Africa claiming up to 60 percent of the population in a large-scale outbreak known as the Black Death. This first wave further extended into a 500-year-long pandemic, the so-called Second Plague Pandemic, which lasted until the early 19th century.

The origins of the Second Plague Pandemic have long been debated. One of the most popular theories has supported its source in East Asia, specifically in China. To the contrary, the only so-far available archaeological findings come from Central Asia, close to Lake Issyk Kul, in what is now Kyrgyzstan. These findings show that an epidemic devastated a local trading community in the years 1338 and 1339. Specifically, excavations that took place almost 140 years ago revealed tombstones indicating that individuals died in those years of an unknown epidemic or "pestilence." Since their first discovery, the tombstones inscribed in Syriac language, have been a cornerstone of controversy among scholars regarding their relevance to the Black Death of Europe.

In this study, an international team of researchers analysed ancient DNA from human remains as well as historical and archaeological data from two sites that were found to contain "pestilence" inscriptions. The team's first results were very encouraging, as DNA from the plague bacterium, Yersinia pestis, was identified in individuals with the year 1338 inscribed on their tombstones. "We could finally show that the epidemic mentioned on the tombstones was indeed caused by plague," says Phil Slavin, one of the senior authors of the study and historian at the University of Sterling, UK.

Researchers found the Black Death's source strain

But could this have been the origin of the Black Death? Researchers have previously associated the Black Death's initiation with a massive diversification of plague strains, a so-called Big Bang event of plague diversity. But the exact date of this event could not be precisely estimated, and was thought to have happened sometime between the 10th and 14th centuries. The team now pieced together complete ancient plague genomes from the sites in Kyrgyzstan and investigated how they might relate with this Big Bang event. "We found that the ancient strains from Kyrgyzstan are positioned exactly at the node of this massive diversification event. In other words, we found the Black Death's source strain and we even know its exact date [meaning the year 1338]," says Maria Spyrou, lead author and researcher at the University of Tübingen.

But where did this strain come from? Did it evolve locally or did it spread in this region from elsewhere? Plague is not a disease of humans; the bacterium survives within wild rodent populations across the world, in so-called plague reservoirs. Hence, the ancient Central Asian strain that caused the 1338-1339 epidemic around Lake Issyk Kul must have come from one such reservoir. "We found that modern strains most closely related to the ancient strain are today found in plague reservoirs around the Tian Shan mountains, so very close to where the ancient strain was found. This points to an origin of Black Death's ancestor in Central Asia," explains Johannes Krause, senior author of the study and director at the Max Planck Institute for Evolutionary Anthropology.

Story Source: Science Daily

 

 

Organic bipolar transistor developed

 Prof. Karl Leo has been thinking about the realization of this component for more than 20 years, now it has become reality: His research group at the Institute for Applied Physics at the TU Dresden has presented the first highly efficient organic bipolar transistor. This opens up completely new perspectives for organic electronics -- both in data processing and transmission, as well as in medical technology applications. The results of the research work have now been published in the leading specialist journal Nature.

The invention of the transistor in 1947 by Shockley, Bardeen and Brattain at Bell Laboratories ushered in the age of microelectronics and revolutionized our lives. First, so-called bipolar transistors were invented, in which negative and positive charge carriers contribute to the current transport, unipolar field effect transistors were only added later. The increasing performance due to the scaling of silicon electronics in the nanometer range has immensely accelerated the processing of data. However, this very rigid technology is less suitable for new types of flexible electronic components, such as rollable TV displays or for medical applications on or even in the body.

For such applications, transistors made of organic, i.e. carbon-based semiconductors, have come into focus in recent years. Organic field effect transistors were introduced as early as 1986, but their performance still lags far behind silicon components.

A research group led by Prof. Karl Leo and Dr. Hans Kleemann at the TU Dresden has now succeeded for the first time in demonstrating an organic, highly efficient bipolar transistor. Crucial to this was the use of highly ordered thin organic layers. This new technology is many times faster than previous organic transistors, and for the first time the components have reached operating frequencies in the gigahertz range, i.e. more than a billion switching operations per second. Dr Shu-Jen Wang, who co-led the project with Dr. Michael Sawatzki, explains: "The first realization of the organic bipolar transistor was a great challenge, since we had to create layers of very high quality and new structures. However, the excellent parameters of the component reward these efforts!" Prof. Karl Leo adds: "We have been thinking about this device for 20 years and I am thrilled that we have now been able to demonstrate it with the novel highly ordered layers. The organic bipolar transistor and its potential open up completely new perspectives for organic electronics, since they also make demanding tasks in data processing and transmission possible." Conceivable future applications are, for example, intelligent patches equipped with sensors that process the sensor data locally and wirelessly communicate to the outside.