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回答题：Evidence of Ancient Hunters
Russian and Norwegian scientists have reported finding stone objects and animal bones in the far north of European Russia. The scientists say the objects provide the first evidence that ancient hunters lived in the area more than 30 thousand years ago. They say this is at least 15 thousand years earlier than experts had thought.
The Russian and Norwegian team worked at a camp along the Usa River and the Arctic Circle. The scientists say they found several ancient stone tools. They also found 123 bones from animals such as horses, reindeer(驯鹿)and wolves.
The scientists say their most important discovery was a tusk from an ancient elephant called a mammoth(猛犸). The huge, curved tooth was more than l meter long. The tusk is covered with small cuts. The scientists believe humans made the marks with sharp-edged stone tools.
The scientists used a process known as radiocarbon(放射性碳)dating to measure the age of the tusk. Radiocarbon dating shows the level of a radioactive form of carbon in a substance. The tests showed the tusk is about 36 thousand years old.
The scientists say they are not sure what kind of humans left the stone objects and bones along the river. They said the people were either early humans called Neanderthals(穴居人,尼安德特人) or modern humans. Modern humans spread through Europe and Asia 30 thousand years ago. The scientists say the ancient people needed a high level of social development to survive in the extremely cold environment.
The objects were discovered about 300 kilometers northeast of another area where scientists say humans once lived. That area has objects more closely linked to modern humans. Those objects are believed to be about 28 thousand years old.
Nature magazine also published a report by John Gowlett of the University of Liverpool in England. He said the discovery shows the ability of early humans to do the unexpected. He also said the discovery should renew debate about the effects of the climate on the movements of early human population.
Before people found stone objects and animal bones in the north of European Russia, some experts thought human beings lived in that area about A．30 thousand years ago
B．20 thousand years ago
C．28 thousand years ago
D．15 thousand years ago
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