Carbon dating chicken bone
Reading: anything older than 50,000 years must then be dated using other methods.Reading: https://science.howstuffworks.com/environmental/earth/geology/Extract from reading: To determine the ages of these specimens, scientists need an isotope with a very long half-life."The most plausible explanation for this transfer was seafaring Polynesians making a round-trip voyage," said Patrick Kirch of the University of California, Berkeley, who led the sweet potato discoveries but was not involved with the Polynesian study."However, it was not possible to completely rule out the ...theory of 'drifting' South Americans on a raft loaded with sweet potatoes," he added. In 2005 a crew of a tiny Mexican fishing boat ran out of fuel and drifted for nine months, winding up near the Marshall Islands, some 8,000 miles (5,500 kilometers) away. But with the new findings of Polynesian chickens, Kirch said, "what we now have is hard, empirical evidence that these contacts actually took place." The next step is to try to find the earliest signs of Polynesians' animals in the Americas.For that, lead author Storey figures the best bet is looking for remains of rats."There are many words in Mapuche language which are close to or identical with Polynesian, [and] the Mapuche war club is very similar to a distinctive Polynesian form," Anderson said. The strongest case is the sweet potato, which originated in the Americas.Polynesians were growing this crop on the Cook Islands as early as a thousand years ago.
Then archaeologist and study co-author Daniel Quiroz, of the Dirección de Bibliotecas, Archivos y Museos in Santiago, dug up 50 chicken bones from at least five individual birds at the Chilean site called El Arenal.Some of the isotopes used for this purpose are uranium-238, uranium-235 and potassium-40, each of which has a half-life of more than a million years.Unfortunately, these elements don’t exist in dinosaur fossils themselves.(See a map of Chile.) The researchers used carbon dating on the same bone used for DNA testing. These dates, which fit well with those of other artifacts found at the same site, were determined with a dating technique called thermoluminescence. The new chicken data are the first confirmation that Polynesians made it to the continent, said study co-author Atholl Anderson of the Australian National University in Canberra.