This study presents genetic data for nine Native American populations from northern North America. Analyses of genetic variation focus on the Pacific Northwest (PNW). Using mitochondrial, Y chromosomal, and autosomal DNA variants, we aimed to more closely address the relationships of geography and language with present genetic diversity among the regional PNW Native American populations. Patterns of genetic diversity exhibited by the three genetic systems were consistent with our hypotheses: genetic variation was more strongly explained by geographic proximity than by linguistic structure. Our findings were corroborated through a variety on analytic approaches, with the unrooted trees for the three genetic systems consistently separating inland from coastal PNW populations. Furthermore, analyses of molecular variance support the trends exhibited by the unrooted trees, with geographic partitioning of PNW populations (F_CT = 19.43%, p = 0.010 ± 0.009) accounting for over twice as much of the observed genetic variation as linguistic partitioning of the same populations (F_CT = 9.15%, p = 0.193 ± 0.013). These findings demonstrate a consensus with previous PNW population studies examining the relationships of genome-wide variation, mitochondrial haplogroup frequencies, and skeletal morphology with geography and language.

There have been a number of previous estimates of human inbreeding for Britons of British descent in Britain, each generally for different social classes, geographical regions, and/or time periods. In this study I attempted to collect all relevant published studies and combine these disparate results into an integrated whole for all of Britain. This was achieved by combining weighted means of the percentage of consanguineous marriages (f%) reported in these earlier studies: weighted according to the number of records each author examined, the proportion of social classes or geographic regions covered by the records, and the “merit” of their individual research methodologies. The percentage occurrences of the various consanguineous marriages, from first to third cousins, were partitioned into a number of time periods, which allowed the weighted mean percentage inbreeding coefficients (F%) to be obtained as a function of time over the period from 1820 to 1960. The resulting temporal scatter distribution of the weighted F% values closely followed a sigmoidal curve, with a nonlinear correlation coefficient of η = 0.974, which fitted well to a generalized logistic function. After about 1900 the value of the weighted F% was essentially constant at about 0.038 ± 0.004, whereas it decreased rapidly from about 0.256 ± 0.011 between 1820 and 1900. The upper-bound value of weighted F% before 1820 from the fitted logistic function is 0.276. This corresponds to a value of the conventional mean inbreeding coefficient F = 0.00276. As the first known attempt to integrate the earlier disparate values of unweighted F% for Britons of British descent for all of Britain, the results of this analysis are promising and should be useful as reference values in other related studies.

Bahía Blanca is an urban city in a historically and geographically strategic location for the mixture of different populations in Argentina. In the present study, 10 Alu elements from the X chromosome are analyzed to characterize the genetic composition of the city's population, to compare it with other worldwide populations, and to explore the usefulness of X-chromosome markers for human population genetics purposes. In the Bahía Blanca sample, 7 of 10 Alu insertion frequencies are polymorphic. X-chromosome Alu results in Bahía Blanca are compared with eight different populations from Africa, Europe, and America. Genetic distance analysis indicates that the Bahía Blanca sample is closer to the European and North African samples (average distances of 0.106 and 0.113) than to the Native American (0.163) and sub-Saharan African samples (0.247). Genetic relationships shown by multidimensional scaling illustrate the intermediate position of Bahía Blanca compared with groups in other regions (European, Native American, and African). Admixture results of the Bahía Blanca sample for X-chromosome markers indicate similar proportions of Native American (0.472) and European parental contributions (0.479) and a minor sub-Saharan African contribution (0.049). These results are consistent with the past decade's genetic studies of Argentinean populations that reported higher Native American and sub-Saharan African contributions than previous data.

The analyses of 15 autosomal and 23 Y-chromosome DNA single-tandem-repeat loci in five rural populations from the Caucasus (four ethnically Georgian and one ethnically Armenian) indicated that two Georgian populations, one from the west and the other from the east of the Greater Caucasus Mountains, were both patrilineally and autosomally most differentiated from each other, and the other populations of Georgians and Armenians held an intermediate position between those two. This pattern may be due to human dispersal from two distinct glacial refugia in the last glacial period and the early Holocene, followed by less gene flow among the populations from the Greater Caucasus than among those from the rest of the Caucasus, where the populations have undergone substantial admixture in historical time. This hypothesis is supported by a strong correlation between genetic differentiation among the populations and landscape permeability to human migrations as determined by terrain ruggedness, forest cover, and snow cover. Although geographic patterns of autosomal and Y-chromosome DNA are not fully concordant, both are influenced by landscape permeability and show a similar east-west gradient. Our results suggest that this permeability was a stronger factor limiting gene flow among human populations in the Caucasus than were ethnic or linguistic boundaries.