Electron paramagnetic resonance useful in building a timeline of humans
It’s “one of the most controversial and surprising hominin finds in a century,” declared an archaeology expert from the Australian Museum. In June, a multi-national team of researchers reported the discovery of hominin remains older than any previously excavated from the Indonesian island of Flores, an important site in archaeological research. The find adds to the understanding of the previously identified Homo floresiensis, a 3-foot-tall, large-footed, small-brained member of the human genus. In something of an ode to the popular J.R.R. Tolkien fantasy novels, “The Hobbit” and “The Lord of the Rings,” the earlier researchers nicknamed these small humans “hobbits.”
Some experts questioned if so-called hobbits were actually a separate species of humans. They suggested the small humans simply might have been malformed members of a human species that had already been identified. The recent announcement about hominin remains tilts the weight of evidence toward the existence of a distinct branch of the hominin tree and toward conferring on hobbits the separate species designation Homo floresiensis.
Since hobbits are some of the most recent members of the family of man, learning about them is of particular interest to scientists aiming to better understand the ancestry of current humans, Homo sapiens. Some archaeologists posit that we, Homo sapiens, may not only have crossed paths with hobbits on the Indonesian island, we even may have contributed to their demise.
In a series of experiments described in the June 9, 2016, issue of Nature, “Age and context of the oldest known hominin fossils from Flores,” researchers detail the methods they used to determine the age of remains found in Mata Menge on Flores Island. The find included teeth and a partial jaw bone, material that, in the field of archaeology, is valuable when it comes to dating human remains.
Remains then and now, constructing a timeline
A priority for archaeologists as they try to understand previous civilizations is to build a timeline. To do that, they employ a variety of research techniques.
Hobbit remains found in 2003 in Liang Bua on Flores island have been there between 190,000 and 50,000 years. The more recently discovered remains of potential hobbit ancestors were unearthed in the Mata Menge area of the Flores island. After analyzing the stone, sediment, fossils and tools, scientists surmised that the Mata Menge fossils belonged to hominins who lived approximately 700,000 years ago, much earlier than previously thought. More research is required to clarify the connection between the humans of Mata Menge and those from Liang Bua.
Electron paramagnetic resonance and two molar teeth
Since the fossils excavated in Mata Menge were in situ, researchers analyzed the sandstone, volcanic ash and other deposits surrounding the fossils as well as the fossils themselves. They also incorporated information on how civilizations used the stone tools found at the site.
The researchers gathered data about the volcanic material around the fossils using single crystal laser fusion 40Ar/39Ar dating. Bruker Micro X-ray Fluorescence Spectrometry proved useful in the process. The fossil teeth were analyzed using coupled uranium-series and electron paramagnetic resonance (EPR) dating. EPR and uranium-series analysis complement one another, enabling researchers to better define timeframes.
The researchers acquired electron paramagnetic resonance (EPR) measurements using a Bruker Elexsys 500 spectrometer. Like 1HNMR, EPR safeguards the sample material, which is critical to protecting rare discoveries such as those uncovered in an archaeological dig. Unlike 1HNMR, in which radio frequency energy is directed at protons, EPR relies on the impact of microwave energy on electrons. EPR is sometimes called electron spin resonance (ESR.)
According to the authors, “U-series dating of the hominin tooth root independently confirms that this specimen has an age of at least 0.55 Ma, whereas combined U-series/ESR dating indicates minimum and maximum ages of around 0.36 Ma and 0.69 Ma. In sum, therefore, we have used multiple dating methods to establish an age of ~0.70 Ma [700,000 years ago] for the hominin fossils.”
The combination of results from the various methods is what led the researchers to the conclusion that the Mata Menge hominins lived about 700,000 years ago, making them the oldest hominins discovered on Flores.
Why hominin research matters
While scientists do not think Homo sapiens are directly descended from hobbits, they do believe Homo sapiens and Homo floresiensis have a shared ancestral heritage.
Homo sapiens are self-aware beings, curious about who we are, where we come from and our place in the world. Understanding our ancestral branches, journeys across the earth, development, interactions and civilizations is part of exploring the very sense of self that may be an attribute unique to our species.
Archaeology, like other scientific work, reveals more than a collection of facts, relics, dates, amounts and bones. Each specific piece of knowledge contributes to a broader, more complete understanding of ourselves, our societies and cultures, and the world we inhabit.
For More Information
Brumm et al., “Age and context of the oldest known hominin fossils from Flores,” Nature,doi:10.1038/nature17663, 2016.
Homo floresiensis: One of the most controversial and surprising hominin finds in a century. http://australianmuseum.net.au/homo-floresiensis
van den Bergh et al., “Homo floresiensis-like fossils from the early Middle Pleistocene of Flores,” Nature,doi:10.1038/nature17999, 2016.
Duval, M. et al. The challenge of dating Early Pleistocene fossil teeth by the combined uranium series–electron spin resonance method: the Venta Micena palaeontological site (Orce, Spain). J. Quaternary Sci. 26, 603–615 (2011).
Duval, M. Electron Spin Resonance (ESR) dating of fossil tooth enamel, in Encyclopedia of Scientific Dating Methods (eds. Rink, W. J. & Thompson, J.) 1–11 (Springer Dordrecht, 2015).
“Oldest-Known “Hobbit”-like Fossils Found,” By Tanya Lewis, The Scientist, June 8, 2016. http://www.the-scientist.com/?articles.view/articleNo/46262/title/Oldest-Known–Hobbit–like-Fossils-Found/.