Quantification of the genetic distance between populations is instrumental in many genetic research initiatives, and a large number of formulas for this purpose have been proposed. However, selection of an appropriate measure for assessing genetic distance between real-world human populations that diverged as a result of mechanisms that are not fully known can be a challenging task. We compared results from nine widely used genetic distance measures to high-density whole-genome SNP genotype data obtained on individuals from 51 world populations. Using population trees and generalized analysis of molecular variance, we found that contradictory inferences could be drawn from analyses that used different distance measures. We determined the grouping of the distance measures in terms of similarity and consistency of their values using concordance, consistency, and Procrustes analyses. Overall, the Cavalli-Sforza and Edwards distance measure differed the most from the other measures. Wright's F_ST for diploid data, the Latter and Reynolds distances, and Nei's minimum distance measures each yielded values that were most consistent with the other eight distance measures in terms of ordering populations based on genetic distance. The Cavalli-Sforza and Edwards distance and Nei's geometric distance were least consistent. Simulation studies showed that the Cavalli-Sforza and Edwards distance is relatively more sensitive in distinguishing genetically similar populations and that the Reynolds genetic distance provides the highest sensitivity for highly divergent populations. Finally, our study suggests that using the Cavalli-Sforza and Edwards distance may provide less power for studies concerning human migration history.

In The Aleutian and Commander Islands and Their Inhabitants (Philadelphia: Wistar Institute of Anatomy and Biology, 1945), Hrdlička proposed a population replacement event in the Aleutian Islands approximately 1,000 years ago based on a perceived temporal shift in cranial morphology. However, the archaeological record indicates cultural, and presumed population, continuity for more than 4,000 years. We use mtDNA haplogroup data in the series of prehistoric eastern Aleutian samples (n = 86) studied craniometrically by Hrdlička to test alternative hypotheses regarding population continuity or replacement in the region. This molecular characterization, in conjunction with direct dating of individual specimens, provided increased resolution for hypothesis testing. Results indicate an apparent shift in mtDNA haplogroup frequencies in the eastern Aleutians approximately 1,000 years ago, in concert with changes in mortuary practices and isotopic signatures reflecting resource acquisition strategies. The earliest Aleut populations were characterized by a high frequency of haplogroup A, as are most modern populations of the North American arctic. Later prehistoric peoples in the Aleutians were characterized by a high frequency of haplogroup D and a correspondingly lower frequency of haplogroup A, a pattern typified by modern Aleut populations.

In this study we characterize the genetic diversity and relationships between the Shia and Sunni Muslim populations of North India and geographically targeted neighboring and global populations. We examined a number of parameters of population genetic and forensic interest based on the allele frequencies from 15 autosomal STR loci (D8S1179, D21S11, D7S820, CSF1PO, D19S433, VWA, TPOX, D18S51, D3S1358, THO1, D13S317, D16S539, D2S1338, D5S818, and FGA). All the studied loci were consistent with Hardy-Weinberg equilibrium, except loci D18S51 and FGA for both Muslim populations, even after applying the Bonferroni correction. The combined power of exclusion and combined power of discrimination values for all 15 STR loci were 0.9999 and >0.99999, respectively, in both Muslim populations. Gene diversity values ranged from 0.6784 (TPOX) to 0.9027 (FGA) for Shia Muslims and from 0.7152 (CSF1PO) to 0.9120 (D18S51) for Sunni Muslims. The observed heterozygosity (H_o) ranged from 0.5833 (D18S51) to 0.8595 (VWA) in Shia Muslims and from 0.6818 (CSF1PO) to 0.8333 (D21S11) in Sunni Muslims and was lower than the expected heterozygosity (H_e) for 11 out of the 15 STRs typed. We analyzed the genetic affinities of the Shia and Sunni Muslim populations with their geographically closest neighboring North Indian, Middle Eastern, East Asian, and European populations using distance-based methods, including neighbor-joining trees and multidimensional scaling. In addition, we estimated the genetic contribution of the putative parental populations included in the analysis to the Shia and Sunni Muslim gene pool using admixture analysis. Although we observed a certain degree of genetic contribution from Iran to both Muslim populations, the results of the phylogenetic analyses based on autosomal STRs suggest genetic relatedness with some of the geographically closest neighboring Hindu religious populations.

The isonymy structure of Buenos Aires was studied based on its surname frequency. Information on 2,552,359 voters of the 28 Buenos Aires districts was used to estimate Lasker's coefficient of relationship by isonymy (R_i), surname diversity according to Fisher's a, the coefficient of consanguinity resulting from random isonymy (F), and Nei's, Lasker's and the Euclidean isonymy distances. These distances were correlated with geographic distances, which were calculated by assigning an arbitrary point to each district and measuring distances on a map of the city. The R_i × 10⁵ and F × 10⁴ averages of the districts located south of Rivadavia Avenue were higher (R_i = 66.08; F = 3.4) than those situated north of that avenue (R_i = 46.60; F = 2.4) (p < 0.001). Fisher's a showed the opposite behavior (north, α = 1,055.5; south, α = 757.2). There was a significant correlation (p < 0.001) between geographic distance and Nei's and the Euclidean distances (0.496 and 0.503, respectively), but the correlation was not significant for Lasker's distance (0.051). These results indicate isolation by distance in the city of Buenos Aires and reveal subdivision of the metropolitan population, with greater consanguinity and a lesser variety of surnames in the districts located in the southern section of the city. This structure agrees with the fragmentation and social, cultural, and economic differences observed among the districts of this Latin American metropolis.

Birth weight is the single most significant determinant of infant mortality and the chances of a newborn to experience healthy development. Low birth weight also appears to be related to higher risks of several important chronic conditions, such as ischemic heart disease, non-insulin-dependent diabetes, and cancer in adults. Thus factors that influence in utero growth and birth weight may have a serious effect on health outcomes many years later in life. Analysis of seasonal variations in birth weights may enable us to suggest specific factors that influence this measure. In this review we summarize the literature on seasonal variations in birth weight. Although causes of seasonal variation in developing regions are more clearly understood, it is not yet clear which factors affect apparent seasonal variation in birth weight in developed countries. In our analysis we observed a pattern of seasonal variations in developed countries that differed between low-, middle-, and high-latitude countries, and we suggest several mechanisms that may be responsible for this diversity. Namely, we suggest that in middle-latitude climates, the large annual temperature range may cause low birth weights during summer, whereas in high- and low-latitude regions variations in sunlight exposure between seasons may contribute to low birth weights apparent during winter. Identification of the suggested causal environmental factors may have public health implications in the development of primary prevention programs for low birth weight and macrosomia in developed countries.

The Copper Age (3rd millennium BC) was characterized by considerable socioeconomic transformations and coincided with the discovery of metallurgy. In this study we reconstruct the peopling of Italy during this period on the basis of dental morphology traits. Dental remains from 41 sites throughout Italy were analyzed; only three of the sites (Laterza and two from Sicily) span from the late Copper Age to the early Bronze Age. To work with adequate samples, we pooled the collections into nine geographically and culturally homogeneous groups. Dental morphological traits were scored on 8,891 teeth from 1,302 individuals using the ASUDAS scale. The correlation between the mean measure of divergence and geographic distances (calculated as air distances) was computed. Multidimensional scaling with the minimum spanning tree and maximum-likelihood methods was applied to assess the relationships between groups. The results revealed a substantial genetic homogeneity among the populations throughout the Italian peninsula during the Copper Age with the exception of Sardinia, which tends to diverge from the continental samples. Phenetic and geographic distances correlate highly significantly only when the southern samples from Sicily and Laterza are removed from the analysis, which indicates that these groups may have experienced genetic admixture with external populations.

Through the sequencing of the complete mitochondrial genome of three individuals of Malagasy ancestry, we completed the characterization of the island southeastern Asian specific M46 haplogroup. We assumed that the association of the np 3588 and np 16278 polymorphisms were M46 specific. In addition, we characterized a novel basal M subhaplogroup: M23. This clade can be defined by one coding region transition at np 10295 and one control region transition at np 16263. Our data suggest the arrival of South Asian migrants before the start of the 15th century and highlights the fact that future studies dealing with the settlement of Madagascar should consider at least three potential source populations (Africa, Indonesia, and India).