Peopling of northern North America: clues from genetic studies.

The paper reviews the archaeological evidence for the length of human occupation in N. America and raises the question whether single or multiple movements of people out of Asia into America occurred, pointing out that considerable genetic variation can occur in small isolated populations in relatively short periods of time. The entire subarctic culture area is populated by speakers of either Athapascan or Algonkian language families. The archaeologic record for tracing the origin of these linguistic groups depends on items of material culture and these have been used to trace the origin of the modern peoples back for a few thousand years. Comparison between groups based on genetic data suffers from unevenness of the data for various Athapascan-and Algonkian-speaking groups. The problem is made more difficult by the smallness of populations and inadequate sample size. The gene diversity measure H of Nei has been used on data for the Athapaskan Dogrib. It suggests that there was probably significant gene diversity present in sub-arctic groups in pre-contact times. Probably this is true also for the Algonkians as typified by the Ojibwa. Examination of the apportioned gene diversity shows that the bulk of the diversity exists within groups rather than between groups. Genetic clues to the peopling of the Americas derive from specific marker genes and from genetic distance statistics. The distribution of the Dia and the GmZa; b03st alleles suggest that Athapaskan genetic links are towards the Bering Sea area while Algonkian connections are towards the south. Nei's genetic distance statistic was calculated for 13 populations using 14 blood group and enzyme loci. The dendrogram derived from the D matrix shows that Eskimos and Chukchi cluster together, and the Athapaskans are closer to the Eskimos than are the Algonkians. These relationships could be valid if the origin of Eskimos goes back to a population of Asiatic Beringia and that populations north of the late Wisconsin ice sheets included a group that led to the Athapaskans whilst populations south of the Wisconsin ice sheet led to the Algonkians.