Humans first settled in the Arctic a mere 4,500 years ago, surviving by exploiting seamammals and fish.
人类最早在4500年前定居在北极,靠捕捞海洋哺乳动物和鱼类生存。
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You might think, therefore, that modem land tortoises have probably stayed on land ever since those early terrestrial times, as most mammals did after a few of them went back to the sea.