Because of the barrier of ice to the east, the Pacific Ocean to the west, and populated areas to the north, there may have been a greater impetus for people to move in a southerly direction.
因为东面有冰的屏障，西面是太平洋，而且北面是人口稠密的地区，所以促使人们向南迁移的动力会更大。
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"To put it more simply," she says, "in the years when strong westerly and southerly winds bring cool water rich in nutrients closer to the Australia coast, there is an increase in the number of fish."