 There remain uncertainties regarding the precise dating of individual sites and regarding conclusions drawn from population genetics studies of contemporary Native Americans.It is also an open question whether this post-LGM migration represented the first peopling of the Americas, or whether there had been an earlier, pre-LGM migration which had reached South America as early as 40,000 years ago.In the early 21st century, the models of the chronology of migration are divided into two general approaches.