Seeps from which gas and oil escape were formative to many ancient cultures and societies. They gave rise to legends surrounding the Delphi Oracle, Chimaera fires and “eternal flames” that were central to ancient religious practices – from Indonesia and Iran to Italy and Azerbaijan. Modern geologists and oil and gas explorers can learn much by delving into the geomythological stories about the religious and social practices of the Ancient World, writes Giuseppe Etiope of the National Institute of Geophysics and Volcanology in Italy. His research is published in the new Springer book Natural Gas Seepage.
“Knowing present-day gas fluxes from a seep and knowing that a seep was active and vigorous two thousand years ago, we can estimate the total amount of gas that has been released to the atmosphere thus far. What can be measured today is probably also valid, at least in terms of orders of magnitude, for the past,” writes Etiope. “Such information may not only be relevant for atmospheric methane budget studies but may also be important for understanding the leaking potential of petroleum systems, whether they are commercial or not.”
Gas-oil seeps have been the source of mythological tales, and many a Biblical and historic event. The observations of ancient naturalists and historians such as Pliny the Elder, who lived two millennia ago, helped to chronicle many of these occurrences, especially in the Mediterranean area. For example, he wrote about Chimaera, a large burning gas seep in modern day Turkey.. In ancient times, the temple of Hephaestus, the Greek god of fire, was built next to it.
Similar “eternal fires” integrated gas and flame emissions into ancient religious practices in many cultures. For instance, the Zoroastrians worshiped the “Pillars of Fire” near modern Baku in Azerbaijan. In Iraq, the Baba Gurgur seep was probably the “burning fiery furnace” into which King Nebuchadnezzar cast the Jews. A legend of ancient Rome reports a stream of crude oil issuing from the ground around 38 BC. It became a meeting spot for the first Roman converts to Christianity, and is now the site for the Basilica of Santa Maria in Trastevere. The sacred Manggarmas flame in Indonesia, which has been active at least since the 15th century, is still used in an annual Buddhist ceremony.
“Knowing that a certain ‘eternal fire’ observed today was already active in Biblical times indicates that it was not triggered by the recent drilling and production of petroleum,” adds Etiope.
Etiope writes that hydrocarbon seeps also influenced the social and technological development of many ancient populations. It not only contributed to global civilization, but was often the source of wars. The first evidence for petroleum usage comes from Syria, where the Neanderthal used natural bitumen on stone tools some 40,000 years ago.
The discovery is reported in the early edition of Proceedings of the National Academy of Sciences the week of May 18. It sheds light, researchers say, on a monumental change that has left modern humans susceptible to osteoporosis, a condition marked by brittle and thinning bones.
At the root of the finding, the researchers say, is the knowledge that putting bones under the “stress” of walking, lifting and running leads them to pack on more calcium and grow stronger.
“There was a lot of evidence that earlier humans had stronger bones and that weight-bearing exercise in modern humans prevents bone loss, but we didn’t know whether the shift to weaker bones over the past 30,000 years or so was driven by the rise in agriculture, diet, urbanization, domestication of the horse or other lifestyle changes,” says Christopher Ruff, Ph.D. , a professor of functional anatomy and evolution at the Johns Hopkins University School of Medicine.
“By analyzing many arm and leg bone samples from throughout that time span, we found that European humans’ bones grew weaker gradually as they developed and adopted agriculture and settled down to a more sedentary lifestyle, and that moving into cities and other factors had little impact.”
The study was a collaborative effort of researchers from across Europe and the United States that began in 2008. The group focused on Europe because it has many well-studied archeological sites, Ruff says, and because the population has relatively little genetic variation, despite some population movements. That meant that any changes observed could be attributed more to lifestyle than to genetics.
For the study, the researchers took molds of bones from museums’ collections and used a portable X-ray machine to scan them, focusing on two major bones from the legs and one from the arms. “By comparing the lower limbs with the upper limbs, which are little affected by how much walking or running a person does, we could determine whether the changes we saw were due to mobility or to something else, like nutrition,” Ruff says.
When they analyzed the geometry of bones over time, the researchers found a decline in leg bone strength between the Mesolithic era, which began about 10,000 years ago, and the age of the Roman Empire, which began about 2,500 years ago. Arm bone strength, however, remained fairly steady. “The decline continued for thousands of years, suggesting that people had a very long transition from the start of agriculture to a completely settled lifestyle,” Ruff says. “But by the medieval period, bones were about the same strength as they are today.”
Ruff notes that Paleolithic-style bones are still likely achievable, at least for younger humans, if they recreate to some extent the lifestyle of their ancestors, notably doing a lot more walking than their peers. He cites studies of professional athletes that have demonstrated how lifestyle is written in our bones. “The difference in bone strength between a professional tennis player’s arms is about the same as that between us and Paleolithic humans,” he says.
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