扫描二维码，直接登录
题库 / GMATLA-CR-39
Charcoal from a hearth site in Colorado, 2,000 miles south of Alaska, is known to be 11,200 years old. Researchers reasoned that, since glaciers prevented human migration south from the Alaska-Siberia land bridge between 18,000 and 11,000 years ago, humans must have come to the Americas more than 18,000 years ago.
Which of the following pieces of new evidence would cast doubt on the conclusion drawn above?
Using new radiocarbon dating techniques, it was determined that the charcoal from the Colorado site was at least 11,400 years old.
Another campsite was found in New Mexico with remains dated at 16,000 years old.
A computer simulation of glacial activity showed that it would already have been impossible for humans to travel south overland from Alaska 18,500 years ago.
Using new radiocarbon dating techniques, it was proved that an ice-free corridor allowed passage south from the Alaska-Siberia land bridge at least 11,400 years ago.
Studies of various other hunting-gathering populations showed convincingly that, once the glaciers allowed passage, humans could have migrated from Alaska to Colorado in about 20 years.
time line: 18500----------18000--------16000--------11400-------11200------11000
Conclusion: 人在18000之前就到美国大陆了
A是support 这个C的，说这个木炭炉子的发现在11400年就在美国南部了，18000----11000又被冰川给隔着了，所以人只有在18000前到美国大陆
B 无关信息： 新墨西哥州在16000发现木炭炉子，不能证明也不能否定人在18000前来了美国
C 18500前不能穿越冰川，不能证明18000的时候的事情
D 11400以前，发现阿拉斯加到西伯利亚大陆直接有一条小道，可以将人从阿拉斯加通到美国大陆，就解释了为啥那个木炭炉子会在11200年被发现，所以就doubt了C，人不一定要18000前来
E 冰川让人通行，也可能是11000以后的事儿了，20年也改变不了这个论证
登录 或 注册 后可以参加讨论