Charcoal revealed true age of new man
When Professor Michael Bird developed a new technique for ageing ‘old’ charcoal, he had no idea that he was about to play a role in the discovery of a completely new species of human.
Professor Bird, of the University of St Andrews, developed the radiocarbon dating technique, which was used to date the fossil remains of Homo floresiensis, the new species of man revealed earlier this week.
Working at the Australian National University, the geoscientist led a team which was primarily interested in when humans first arrived in Australia as debate raged over whether they arrived 40,000 years ago, or as early as 100,000 years ago. It was for this purpose that Professor Bird and his colleagues developed the new methodology.
Professor Bird said: “We had been using the new method to date charcoal back into the 50,000 year time range and the technique had already been used to successfully date archaeological charcoal from Australia, South East Asia and South Africa. We also used it to successfully redate possibly the oldest known site – and one of the most controversial archaeological sites – in Brazil. This was well before the remains of Homo floresiensis were even recovered.”
The team received some charcoal from archaeologist Mike Morewood in 2001, who had excavated the material from a limestone cave on an exotic Indonesian island. Professor Morewood thought the charcoal might be quite old and was associated with artefacts so it looked like an attractive dating project. Even the oldest dates were surprisingly young, only 13,000 years, which seemed a disappointment at the time.
Fast forward in time and half-way across the World to Belfast, where an original member of the Australian team, Dr Chris Turney received another batch of ancient charcoal from Professor Morewood. The dates were not much older, about 18,000 years, but given that these samples were associated with the discovery of a one metre tall female member of an entirely new species of the human family tree, the dates were now of considerably greater significance.
The dating of the charcoal provided the crucial evidence that the dwarf-sized descendant of Homo erectus lived until relatively recently. While other dating techniques suggest that the new species may have been present on the island from at least 74,000 years ago, the radiocarbon dating revealed that the species overlapped significantly in time with Homo sapiens.
The finding has meant a complete re-evaluation of the history of the evolution of man, with the possibility that this 3-foot tall species with a brain the size of a grapefruit could have lived alongside modern man.
Professor Bird worked with an international team of researchers from Australia, Indonesia, the Netherlands, Canada and Belfast on the project. Along with Dr Turney and Professor Keith Fifield of the Australian National University, Professor Bird developed the new technique for radiocarbon dating of charcoal called ABOX-SC.
The new method of carbon dating is more reliable than previous techniques and can yield reliable ages on ancient deposits of charcoal. Using this and other techniques, the team were able to determine the age of the remains of Homo floresiensis, found six metres beneath layers of rubble and clay.
Surrounding the remains of the new species were fossils of small animals such as a fish, frog, snake, tortoise and bird and larger mammals including a monkey, deer, pig and porcupine. Archaeologists also found stone artefacts, including a large chopping tool, which they believe were made by the dwarf species.
Professor Bird, Chair of Environmental Change at the School of Geography and Geosciences at St Andrews, said:
“This is a very important discovery as it adds an entirely new branch to our family tree, and the close working relationship between the archaeologists and geoscientists working on this project has meant that we can be very certain of the age of these fossils.”
Radiocarbon exists in living organisms and radiocarbon dating relies on the fact that once the organism dies, the radiocarbon in the organism is no longer replenished and so decreases systematically with time. By measuring the amount of radiocarbon remaining in an originally live, carbon-containing sample, it is possible to calculate the time elapsed since the death of the organism.
Professor Bird continued: “After the initial batch of charcoal from Liang Bua was dated there was a bit of a disappointment, because it was found to be not that old. But this has ended up being the really interesting bit, as it demonstrates the coincidence of the two species on the island at the same time, and the fact that the new species lived until so recently.”
NOTE TO EDITORS:
PROFESSOR BIRD IS AVAILABLE FOR INTERVIEW ON 01334 463928 OR 07786 123 201.
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