Periodic Reporting for period 4 - ECHOES (Exact Chronology of Early Societies)
Reporting period: 2021-08-01 to 2023-02-28
Exact Chronology of Early Societies (ECHOES) was a project based at the University of Groningen. It was aimed at investigating large strikes of cosmic radiation on Earth. These phenomena, often known as Miyake Events (MEs), are potentially a threat to society, but something of a benefit for chronology, the science of age estimation. The events cause production of radiocarbon to increase dramatically in the atmosphere and, through photosynthesis, the resultant spikes in radiocarbon concentration are incorporated by growing trees. The radiation strikes are so intense they pose a threat to modern society as they would likely damage satellite and telecommunication systems. ECHOES aimed to understand these MEs and to determine whether there was any pattern to their occurrence, in order to future proof satellite communication networks. MEs also offered the tantalising prospect of exact-year dating because they leave distinct radiocarbon signatures in contemporaneous plant material. To elaborate, archives of wood already exist within which the age of each tree-ring is precisely known, so the exact years in which spikes in radiocarbon concentration occurred can be identified. By finding MEs in old wooden artefacts, for example, and matching their radiocarbon profiles with ones in the known-age tree-ring archives, ECHOES aimed to date items to the exact year.
ECHOES revealed a lot of new information about the nature of MEs. We found variations in the spikes that may lead to a better understanding of their origin. We disproved the existence of some spikes that had already been claimed in the literature. We closely investigated the relationship between MEs and phases of solar activity. The Sun progresses from higher to lower levels of output every 11 years or so. Initially, we thought the events occurred during solar maxima but later we discovered that this relationship was ambiguous. Nonetheless, our tree ring measurements have helped to characterise previously indistinct solar behaviour, like the existence of a long period of reduced solar activity around 400 BCE. We also collaborated with the University of Queensland in their quest to develop a new software package capable of analysing the data from MEs in great detail. There is still much to discover about the nature of MEs but a good foundation for their understanding has now been laid.
With regard to the use of MEs for exact dating, ECHOES was a runaway success. We dated the first archaeological site of unknown age using the method in 2020. Our study, published in PNAS, was able to pinpoint the age of a massive structure in Siberia and, as a result, for the first time reveal its actual use. We have also been able to date sites in Turkey, Germany, Spain and Latvia to the exact year, although not all these studies have yet been published. Our greatest success, no doubt, was the dating of the first Europeans in the Americas. This study, published in Nature, showed that the Vikings had been active in North America in 1021 CE. The story gained an enormous amount of attention in both academic and popular literature.
ECHOES revealed a lot of new information about the nature of MEs. We found variations in the spikes that may lead to a better understanding of their origin. We disproved the existence of some spikes that had already been claimed in the literature. We closely investigated the relationship between MEs and phases of solar activity. The Sun progresses from higher to lower levels of output every 11 years or so. Initially, we thought the events occurred during solar maxima but later we discovered that this relationship was ambiguous. Nonetheless, our tree ring measurements have helped to characterise previously indistinct solar behaviour, like the existence of a long period of reduced solar activity around 400 BCE. We also collaborated with the University of Queensland in their quest to develop a new software package capable of analysing the data from MEs in great detail. There is still much to discover about the nature of MEs but a good foundation for their understanding has now been laid.
With regard to the use of MEs for exact dating, ECHOES was a runaway success. We dated the first archaeological site of unknown age using the method in 2020. Our study, published in PNAS, was able to pinpoint the age of a massive structure in Siberia and, as a result, for the first time reveal its actual use. We have also been able to date sites in Turkey, Germany, Spain and Latvia to the exact year, although not all these studies have yet been published. Our greatest success, no doubt, was the dating of the first Europeans in the Americas. This study, published in Nature, showed that the Vikings had been active in North America in 1021 CE. The story gained an enormous amount of attention in both academic and popular literature.
The results of the ECHOES project fall into three main groups: understanding nature of MEs; perfecting how to use them for dating; and then applying the new method to historical questions. We blazed a trail in the application of sophisticated data science techniques to analyse MEs. This work, driven largely by our post-doc, Andreas Neocleous, produced three papers in the first two years of the project. This focus was largely continued in conjunction with collaborators at the University of Queensland. Recently that collaboration generated a new open source online tool called ticktack for analysing ME data. Meanwhile Andrea Scifo, as part of his PhD, spent time trying to relate MEs to the solar cycle. His 2019 paper in Scientific Reports suggested a link might exist but we are now less certain. Andrea went on to show that two MEs already published in the scientific literature are actually not real. He, Margot Kuitems and I also collaborated with ANSTO on a study of MEs not using radiocarbon but similarly formed isotopes that are detectable in ice cores. This work is yet to be published but it will also substantially challenge prevailing interpretations of the nature of MEs. The three of us, and latterly Pinar Erdil and Safoora Kamjan, have also had enormous success at using MEs for dating. Largely these successes were based on the technical skills of Margot and analytical skills of Andrea, both of whom are also drafting how-to guides on best practice in 'spike dating'. In 2020, our team was the first to date a site of previously unknown age with the method, and published that in PNAS. We used our knowledge of high-precision radiocarbon dating on wood to assist with the dating of a major volcanic eruption in the 4th century CE. This work, led by Oxford, was also published in PNAS. We have also applied these approaches to the important ancient Egyptian timeline. There are two main versions of this record over the first 1000 years of its span (~2700-1700 BCE), our work has shown that only the older of the two options is correct. This work will be published shortly, and we are aiming for PNAS once again. We have also dated several other significant sites, in Turkey, Spain, Germany and Latvia, but all except the last of these articles are yet to come out. Once more, however, it is undeniable that our greatest triumph was proving that the Vikings were in the Americas in 1021 CE. This captured the public's imagination and stunned the academic world by showing everyone what was now possible. This paper, published in Nature, was covered by the New York Times, The Wall Street Journal, The Guardian, Le Monde, indeed hundreds of newspapers around the world. Margot and I were even interviewed live on global TV news channels. The article went on to attain the highest score for impact for any study from our university, according to the leading website for this information, Altmetric. Moreover, our greatest accolade of all really, only came out this year. Nature featured our method, and its application to the Vikings in the Americas, as one of its Seven Technologies to Watch in 2023, alongside huge scientific breakthroughs like CRISPR-Cas gene editing and the James Webb Space Telescope. And last week, Science published a five-page feature article explaining the method and focusing on the contribution our project has made to its development.
The project has now ended, although several academic outputs have yet to be published. In terms of the new dating method, we tried hard to push the boundaries of what it could manage; for example, aiming not just for annual but sub-annual resolution, and proving that the method could be applied to wood species too tricky to be dated in any other way. We also believe that our collaborations with CEZ Mannheim; ANSTO, especially on the ice core work; and the University of Queensland, especially on the data science work; will ultimately reveal the complete picture of why, and how frequently, MEs occur.