Read the text and answer the questions “Scientists have found the oldest DNA evidence yet of humans’ biological history. But instead of neatly clarifying human evolution, the finding is adding new mysteries. In a paper in the journal Nature, scientists reported Wednesday that they had saved ancient human DNA from a fossil dating back about 400,000 years, shattering the previous record of 100,000 years.
The mismatch between the anatomical and genetic evidence surprised the scientists, who are now rethinking human evolution over the past few hundred thousand years. It is possible, for example, that there are many extinct human populations that scientists have yet to discover. Right now, we’ve basically generated a big question mark,” said Matthias Meyer, a geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a co-author of the new study.
Finding such ancient human DNA was a major advance, said David Reich, a geneticist at Harvard Medical School who was not involved in the research. “That’s an amazing, game-changing thing,” he said.
When Dr. Meyer and his colleagues found ancient human DNA inside they thought that it would be a very early Neanderthal,” Dr. Meyer said.
But the DNA did not match that of Neanderthals. Dr. Meyer then compared it to the DNA of the Denisovans, the ancient human lineage that he and his colleagues had discovered in Siberia in 2010. He was shocked to find that it was similar. Everybody had a hard time believing it at first, Dr. Meyer said. So we generated more and more data to nail it down. The extra research confirmed that the DNA belonged on the Denisovan branch of the human family tree. The new finding is hard to settle with the picture of human evolution that has been emerging based on fossils and ancient DNA…
Hints at new hidden difficulties in the human story came from a 400,000-year-old bone found in a cave in Spain called “the pit of bones”. The scientific team used new methods to extract the ancient DNA from the fossil and ancient DNA…

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