题目选项分析

Most archaeologists have held that people first reached the Americas less than 20, 000 years ago by crossing a land bridge into North America.But recent discoveries of human shelters in South America dating from 32, 000 years ago have led researchers to speculate that people arrived in South America first, after voyaging across the Pacific, and then spread northward.

Which of the following, if it were discovered, would be pertinent evidence against the speculation above?

【选项】Some North American sites of human habitation predate any sites found in South America.