Traces of medieval migrations in a socially stratified population from Northern Italy. Evidence from uniparental markers and deep-rooted pedigrees.

Social and cultural factors had a critical role in determining the genetic structure of Europe. Therefore, socially stratified populations may help to focus on specific episodes of European demographic history. In this study, we use uniparental markers to analyse the genetic structure of Partecipanza in San Giovanni in Persiceto (Northern Italy), a peculiar institution whose origins date back to the Middle Ages and whose members form the patrilineal descent of a group of founder families. From a maternal point of view (mtDNA), Partecipanza is genetically homogeneous with the rest of the population. However, we observed a significant differentiation for Y-chromosomes. In addition, by comparing 17 Y-STR profiles with deep-rooted paternal pedigrees, we estimated a Y-STR mutation rate equal to 3.90 * 10(-3) mutations per STR per generation and an average generation duration time of 33.38 years. When we used these values for tentative dating, we estimated 1300-600 years ago for the origins of the Partecipanza. These results, together with a peculiar Y-chromosomal composition and historical evidence, suggest that Germanic populations (Lombards in particular) settled in the area during the Migration Period (400-800 AD, approximately) and may have had an important role in the foundation of this community.

Discordant patterns of mtDNA and ethno-linguistic variation in 14 Iranian Ethnic groups.

BACKGROUND/AIMS: Present-day Iran has long represented a natural hub for the expansion of human genes and cultures. That being so, the overlapping of prehistoric and more recent demographic events interacting at different time scales with geographical and cultural barriers has yielded a tangled patchwork of anthropological types within this narrow area. This study aims to comprehensively evaluate this ethnic mosaic by depicting a fine-grained picture of the Iranian mitochondrial landscape. METHODS: mtDNA variability at both HVS-I and coding regions was surveyed in 718 unrelated individuals belonging to 14 Iranian ethnic groups characterized by different languages, religions and patterns of subsistence. RESULTS: A discordant pattern of high ethno-linguistic and low mtDNA heterogeneity was observed for the whole examined Iranian sample. Geographical factors and cultural/linguistic differences actually represented barriers to matrilineal gene flow only for the Baloch, Lur from Yasouj, Zoroastrian and Jewish groups, for which unusual reduced levels of mtDNA variability and high inter-population distances were found. CONCLUSION: Deep rooting genealogies and endogamy in a few of the examined ethnic groups might have preserved ancestral lineages that can be representative of Proto-Indo-Iranian or prehistoric mitochondrial profiles which survived relatively recent external contributions to the Iranian gene pool.

Growth and malnutrition of rural Zimbabwean children (6-17 years of age).

The rural environment is an important factor in delayed growth in developing countries. The aim of this study was to investigate the effects of poor rural living conditions on the growth of a Shona sample in Zimbabwe. In total, 982 subjects aged 6-17 years were analyzed. Mean values of height, weight, skinfolds (triceps, subscapular, suprailiac, biceps, medial calf), cormic index, body mass index (BMI), arm composition (total upper arm area, upper arm muscle area, arm fat area, and arm fat index), fat percentage (%F), centripetal fat ratio (CFR), and the contribution of each skinfold to the adiposity of the trunk and upper limbs are presented. Weight, height, BMI, cormic index, SSCP, TRCP, arm circumference, and arm composition are compared with NHANES percentiles. Boys and girls showed stunting and underweight at ages 11-15 and 8-15, respectively; boys presented particularly severe malnutrition and their means of height and weight were below the 10th percentile. The means of arm circumference, UMA, UFA, and TRCP were below the 15th percentile in both sexes. The contribution of the skinfolds generally showed an overall prevalence of TRCP in both sexes; the contribution of SSCP was prevalent only for the 16- to 17-year-old boys. Males presented a higher CFR than girls after 14 years while females showed an irregular pattern. There was a high incidence of brachycormia and mesocormia in females and males, respectively. Height, weight, and BMI were similar to the values observed in other sub-Saharan countries, although body size was slightly larger than in South Africa and smaller than in Tanzania. The results provide a useful database for future comparisons.

Analysis of nucleotide diversity of NAT2 coding region reveals homogeneity across Native American populations and high intra-population diversity.

N-acetyltransferase 2 (NAT2), an important enzyme in clinical pharmacology, metabolizes antibiotics such as isoniazid and sulfamethoxazole, and catalyzes the transformation of aromatic and heterocyclic amines from the environment and diet into carcinogenic intermediates. Polymorphisms in NAT2 account for variability in the acetylator phenotype and the pharmacokinetics of metabolized drugs. Native Americans, settled in rural areas and large cities of Latin America, are under-represented in pharmacogenetics studies; therefore, we sequenced the coding region of NAT2 in 456 chromosomes from 13 populations from the Americas, and two from Siberia, detecting nine substitutions and 11 haplotypes. Variants *4 (37%), *5B (23%) and *7B (24%) showed high frequencies. Average frequencies of fast, intermediate and slow acetylators across Native Americans were 18, 56 and 25%, respectively. NAT2 intra-population genetic diversity for Native Americans is higher than East Asians and similar to the rest of the world, and NAT2 variants are homogeneously distributed across native populations of the continent.

Unravelling migrations in the steppe: mitochondrial DNA sequences from ancient central Asians.

This study helps to clarify the debate on the Western and Eastern genetic influences in Central Asia. Thirty-six skeletal remains from Kazakhstan (Central Asia), excavated from different sites dating between the fifteenth century BC to the fifth century AD, have been analysed for the hypervariable control region (HVR-I) and haplogroup diagnostic single nucleotide polymorphisms (SNPs) of the mitochondrial DNA genome. Standard authentication criteria for ancient DNA studies, including multiple extractions, cloning of PCR products and independent replication, have been followed. The distribution of east and west Eurasian lineages through time in the region is concordant with the available archaeological information: prior to the thirteenth-seventh century BC, all Kazakh samples belong to European lineages; while later an arrival of east Eurasian sequences that coexisted with the previous west Eurasian genetic substratum can be detected. The presence of an ancient genetic substratum of European origin in West Asia may be related to the discovery of ancient mummies with European features in Xinjiang and to the existence of an extinct Indo-European language, Tocharian. This study demonstrates the usefulness of the ancient DNA in unravelling complex patterns of past human migrations so as to help decipher the origin of present-day admixed populations.

Body size, composition, and blood pressure of high-altitude Quechua from the Peruvian Central Andes (Huancavelica, 3,680 m).

Although much information is available about the effects of high altitude on physiological characteristics, less is know about its effect on body composition. In the present study, anthropometric and body composition variables were investigated in a sample of 77 adult Quechua males from the Peruvian Central Andes (Huancavelica, 3,680 m). The subjects are shorter in relation to body weight than other ethnic groups, whereas body proportions are macrocormic (indicating a long trunk relative to the lower extremities), with intermediate values of the acromial-iliac index. All skinfold thicknesses are low (approximately 15th percentiles of NHANES reference values for the triceps and subscapular skinfolds), but tend to be higher than in the other Quechua populations. Similar results are obtained when percentage fat is estimated. Somatotypes are dominant in mesomorphy with very low ectomorphy. Comparison with a sample of high-altitude Kirghiz (3,200 m), previously studied with the same methods, shows higher values in the Peruvian sample for all variables related to adiposity. The presence of low adiposity in the Quechua population could be associated with stresses of the high-altitude environment. Mean values of blood pressure are very low and there is no correlation with age.

Genetic differentiation in South Amerindians is related to environmental and cultural diversity: evidence from the Y chromosome.

The geographic structure of Y-chromosome variability has been analyzed in native populations of South America, through use of the high-frequency Native American haplogroup defined by the DYS199-T allele and six Y-chromosome-linked microsatellites (DYS19, DYS389A, DYS389B, DYS390, DYS391, and DYS393), analyzed in 236 individuals. The following pattern of within- and among-population variability emerges from the analysis of microsatellite data: (1) the Andean populations exhibit significantly higher levels of within-population variability than do the eastern populations of South America; (2) the spatial-autocorrelation analysis suggests a significant geographic structure of Y-chromosome genetic variability in South America, although a typical evolutionary pattern could not be categorically identified; and (3) genetic-distance analyses and the analysis of molecular variance suggest greater homogeneity between Andean populations than between non-Andean ones. On the basis of these results, we propose a model for the evolution of the male lineages of South Amerindians that involves differential patterns of genetic drift and gene flow. In the western part of the continent, which is associated with the Andean area, populations have relatively large effective sizes and gene-flow levels among them, which has created a trend toward homogenization of the gene pool. On the other hand, eastern populations-settled in the Amazonian region, the central Brazilian plateau, and the Chaco region-have exhibited higher rates of genetic drift and lower levels of gene flow, with a resulting trend toward genetic differentiation. This model is consistent with the linguistic and cultural diversity of South Amerindians, the environmental heterogeneity of the continent, and the available paleoecological data.

Marriage behaviour in the Alpine Non Valley from 1825 to 1923.

BACKGROUND: The study is part of a research project on the marital structure of mountain populations from the Eastern Italian Alps. Little is known about marriage patterns in this Alpine area. AIM: The aim of the study is to evaluate the extent of reproductive isolation in some communities of the Non Valley (Trentino, Italy) and to investigate its microgeographic and temporal changes over the period 1825-1923. SUBJECTS AND METHODS: 4518 microfilmed marriage records from registers of seven parishes of the Non Valley were used to analyse the following: endogamy rate, inbreeding calculated both from dispensations and from isonymy, repeating pairs of surnames in marriages, isonymic relationships. RESULTS: The results show notable variability among parishes in the levels of endogamy (40-73%), inbreeding (alpha: 1.9-4.57; Ft: 0.0073-0.019) and subdivision (RPr/RP: 0.5-1.3). The values are relatively stable over the course of a century, apart from a rise in inbreeding indicated by dispensations and a slight decrease of endogamy at the beginning of the 20th century. Isonymic relationships reflect geographic proximity between populations, with minimum changes through time. CONCLUSIONS: Variations in the level of reproductive isolation within the Non Valley are consistent with the different geographic characteristics and population sizes of the settlements. Comparison with data obtained from previous studies in the Eastern Italian Alps shows that the values of the investigated biodemographic indicators are in line with the geography and altitude of the area. The slight differences in temporal trend of endogamy and inbreeding can be correlated with different migration patterns.

Genetic structure of Quechua-speakers of the Central Andes and geographic patterns of gene frequencies in South Amerindian populations.

A sample of 141 Quechua-speaking individuals of the population of Tayacaja, in the Peruvian Central Andes, was typed for the following 16 genetic systems: ABO, Rh, MNSs, P, Duffy, AcP1, EsD, GLOI, PGM1, AK, 6-PGD, Hp, Gc, Pi, C3, and Bf. The genetic structure of the population was analyzed in relation to the allele frequencies available for other South Amerindian populations, using a combination of multivariate and multivariable techniques. Spatial autocorrelation analysis was performed independently for 13 alleles to identify patterns of gene flow in South America as a whole and in more specific geographic regions. We found a longitudinal cline for the AcP1*a and EsD*1 alleles which we interpreted as the result of an ancient longitudinal expansion of a putative ancestral population of modern Amerindians. Monmonnier's algorithm, used to identify areas of sharp genetic discontinuity, suggested a clear east-west differentiation of native South American populations, which was confirmed by analysis of the distribution of genetic distances. We suggest that this pattern of genetic structures is the consequence of the independent peopling of western and eastern South America or to low levels of gene flow between these regions, related to different environmental and demographic histories.

Lung volume, chest size, and hematological variation in low-, medium-, and high-altitude central Asian populations.

To evaluate adaptive responses to high-altitude environment, we examined three groups of healthy adult males from Central Asia: 94 high-altitude (HA) Kirghiz subjects (3,200 m above sea level); 114 middle-altitude (MA) Kazakh subjects (2,100 m), and 90 low-altitude (LA) Kirghiz subjects (900 m). Data on chest size (chest perimeter and chest diameter), lung volume (forced expiratory volume (FEV) and forced expiratory volume in 1 sec (FEV1)), and hematological parameters (hemoglobin, erythrocytes, hematocrit, and SaO(2)) are discussed. The results show that 1) chest shape is less flat in the samples living at higher altitude. In the HA sample, chest perimeter is lower but chest excursion is high. 2) In the highlanders, forced vital capacity (FVC) and FEV1 are no higher than in the other samples, even when corrected for stature and body weight. The negative correlation between FVC-FEV1 and age decreases with increasing altitude. 3) The HA and MA samples have higher values of hemoglobin, erythrocytes, and hematocrit. The HA sample has lower SaO(2) and higher arterial oxygen content than the LA sample. No association between hematocrit and age was detected in the four samples. The results indicate that the high-altitude Kirghiz present features of developmental acclimatization to hypobaric hypoxia which are also strongly influenced by other major high-altitude environmental stresses.

Relationships between blood pressure, anthropometric characteristics and blood lipids in high- and low-altitude populations from Central Asia.

We studied the relationships between blood pressure, anthropometric characteristics and blood lipids in 72 low altitude (LA) Uighurs (600 m), 91 LA-Kirghizs (900 m), 117 medium altitude (MA) Kazakhs (2100 m) and 94 high altitude (HA) Kirghizs (3200 m). All subjects were male and had a similar age (p = ns, ANOVA; range for all 374 subjects: 18-66 yr). Body weight (Wt), body mass index (BM1) and the sum of four skinfolds (4SF) were significantly lower in HA-Kirghizs than the remaining groups (p < 0.0005, p < 0.0005 and p < 0.05 respectively, ANOVA). However, no difference was found in body fat distribution as detected by waist:hip circumference (WHR) and triceps:subscapular skinfold ratios (TSR; p = ns, ANOVA). Stage 1 hypertension was detected in 18% of LA-Uighurs, 2% of LA-Kirghizs, 4% of MA-Kazakhs and 1% of HA-Kirghizs; stage 2 hypertension was detected in 2% of LA-Uighurs and none of the remaining groups; no subject had stage 3 hypertension (The Joint National Committee on Prevention. Detection, Evaluation and Treatment of High Blood Pressure 1997). Blood cholesterol (CH) and triglycerides (TG) did not differ between groups (p = ns, ANOVA). The relationships between systolic (SBP) or diastolic (DBP) blood pressure and age, Wt, BMI, 4SF, WHR, TSR, CH and TG were independent from altitude (p = ns, ANCOVA). In the pooled sample (n = 374), age explained 1 and 3% of SBP (p < 0.05) and DBP (p < 0.005) variance respectively, Wt was the best predictor of SBP and DBP explaining 11 and 10% of their variance respectively (p < 0.0001) and CH explained 5% of DBP variance (p < 0.0001). In conclusion, hypertension is more frequent in LA- than MA- and HA-subjects from Central Asia. However, anthropometric characteristics and blood lipids do similarly contribute to explain blood pressure in these subjects.

Hematological and pulmonary responses to high altitude in Quechuas: a multivariate approach.

This study investigates the relationships among hematological variables, pulmonary function, and age in a sample of high-altitude natives. The following anthropometric and physiological variables were examined in 77 adult Quechua males from the Peruvian Central Andes (Huancavelica, 3,680 m): height, weight, sitting height, chest diameters, chest and abdominal circumferences, forced vital capacity (FVC), forced expiratory volume at 1 sec (FEV1), peak expiratory flow (PEF), hemoglobin concentration (Hb), red blood cells (RBC), hematocrit (Htc), diastolic and systolic blood pressure, body temperature, pulmonary rate, and pulse rate. The means of these variables for the Huancavelica sample fall within the range of variability previously observed in Andean populations. Principal components analysis and canonical correlation analysis suggest that in this native Andean population: 1) aging decreases lung function but does not affect hematological features, and 2) there is a negative age-independent correlation between lung function (FVC, FEV1, PEF) and hematological traits (Hb, RBC, Htc).

Geographic patterns of mtDNA diversity in Europe.

Genetic diversity in Europe has been interpreted as a reflection of phenomena occurring during the Paleolithic ( approximately 45,000 years before the present [BP]), Mesolithic ( approximately 18,000 years BP), and Neolithic ( approximately 10,000 years BP) periods. A crucial role of the Neolithic demographic transition is supported by the analysis of most nuclear loci, but the interpretation of mtDNA evidence is controversial. More than 2,600 sequences of the first hypervariable mitochondrial control region were analyzed for geographic patterns in samples from Europe, the Near East, and the Caucasus. Two autocorrelation statistics were used, one based on allele-frequency differences between samples and the other based on both sequence and frequency differences between alleles. In the global analysis, limited geographic patterning was observed, which could largely be attributed to a marked difference between the Saami and all other populations. The distribution of the zones of highest mitochondrial variation (genetic boundaries) confirmed that the Saami are sharply differentiated from an otherwise rather homogeneous set of European samples. However, an area of significant clinal variation was identified around the Mediterranean Sea (and not in the north), even though the differences between northern and southern populations were insignificant. Both a Paleolithic expansion and the Neolithic demic diffusion of farmers could have determined a longitudinal cline of mtDNA diversity. However, additional phenomena must be considered in both models, to account both for the north-south differences and for the greater geographic scope of clinical patterns at nuclear loci. Conversely, two predicted consequences of models of Mesolithic reexpansion from glacial refugia were not observed in the present study.

Patterns of gene flow inferred from genetic distances in the Mediterranean region.

The analysis of population structure may lead to inferences about demographic phenomena. In particular, regions of sharp genetic differentiation suggest the existence of factors that impaired gene flow and increased the evolutionary role of genetic drift. Here, we present an analysis of a data set of 10 allele frequencies in 39 populations of the Mediterranean region. As a preliminary step, we describe spatial patterns of allele frequencies using spatial autocorrelation analysis. We then construct a network connecting localities and estimate genetic distances along the edges of the network. By applying specific algorithms, we locate on the map the areas of sharpest genetic differentiation, or genetic boundaries. The main boundaries separate the northern and the southern coasts, especially in their western portions; in addition, several localities appear genetically isolated. The comparatively high genetic differentiation across the western Mediterranean, where the sea distances between localities are shorter, strongly suggests that the sea distance by itself can hardly be regarded as a major isolating factor among these populations. On the contrary, the decrease in genetic resemblance between populations of the 2 coasts as one proceeds westward may reflect an increased genetic exchange in the eastern Mediterranean basin or independent human dispersal along the 2 coasts or both.

Sex-specific migration patterns in Central Asian populations, revealed by analysis of Y-chromosome short tandem repeats and mtDNA.

Eight Y-linked short-tandem-repeat polymorphisms (DYS19, DYS388, DYS389I, DYS389II, DYS390, DYS391, DYS392, and DYS393) were analyzed in four populations of Central Asia, comprising two lowland samples-Uighurs and lowland Kirghiz-and two highland samples-namely, the Kazakhs (altitude 2,500 m above sea level) and highland Kirghiz (altitude 3,200 m above sea level). The results were compared with mtDNA sequence data on the same individuals, to study possible differences in male versus female genetic-variation patterns in these Central Asian populations. Analysis of molecular variance (AMOVA) showed a very high degree of genetic differentiation among the populations tested, in discordance with the results obtained with mtDNA sequences, which showed high homogeneity. Moreover, a dramatic reduction of the haplotype genetic diversity was observed in the villages at high altitude, especially in the highland Kirghiz, when compared with the villages at low altitude, which suggests a male founder effect in the settlement of high-altitude lands. Nonetheless, mtDNA genetic diversity in these highland populations is equivalent to that in the lowland populations. The present results suggest a very different migration pattern in males versus females, in an extended historical frame, with a higher migration rate for females.

Trading genes along the silk road: mtDNA sequences and the origin of central Asian populations.

Central Asia is a vast region at the crossroads of different habitats, cultures, and trade routes. Little is known about the genetics and the history of the population of this region. We present the analysis of mtDNA control-region sequences in samples of the Kazakh, the Uighurs, the lowland Kirghiz, and the highland Kirghiz, which we have used to address both the population history of the region and the possible selective pressures that high altitude has on mtDNA genes. Central Asian mtDNA sequences present features intermediate between European and eastern Asian sequences, in several parameters-such as the frequencies of certain nucleotides, the levels of nucleotide diversity, mean pairwise differences, and genetic distances. Several hypotheses could explain the intermediate position of central Asia between Europe and eastern Asia, but the most plausible would involve extensive levels of admixture between Europeans and eastern Asians in central Asia, possibly enhanced during the Silk Road trade and clearly after the eastern and western Eurasian human groups had diverged. Lowland and highland Kirghiz mtDNA sequences are very similar, and the analysis of molecular variance has revealed that the fraction of mitochondrial genetic variance due to altitude is not significantly different from zero. Thus, it seems unlikely that altitude has exerted a major selective pressure on mitochondrial genes in central Asian populations.

Surnames and genetic structure of a high-altitude Quechua community from the Ichu River Valley, Peruvian Central Andes, 1825-1914.

Changes in isolation, inbreeding, population subdivision, and isonymous relationships are examined in six Quechua communities from the upper valley of the Ichu River in the Peruvian Central Andes (3700 m). All marriages registered between 1825 and 1914 in the Parish of Santa Ana were analyzed. The data (1680 marriages) were divided into 2 periods (1825-1870 and 1871-1914) and into the 6 villages that constitute the parish. Endogamy rates are between 81% and 100%, indicating high levels of reproductive isolation. The inbreeding indicated by isonymy (Ft, Fr, and Fn) is lower than in other mountain populations studied. Isonymy values, calculated from the different surname combinations made possible by the Ibero-American Surnames System, indicate a strong rejection of consanguineous marriages, particularly between patrilineal relatives, in agreement with the parental structure typical of Andean populations. The comparison between observed and expected repeated-pair values reveals a moderate level of subdivision within populations, which could be related to cultural and socioeconomic factors. Nonmetric multidimensional scaling was used to investigate temporal changes in the isonymous relationships among the communities. The results reveal a decrease in the interpopulational variability measured by surnames, in agreement with an increase in exogamy. Surnames and data contained in historical and demographic records yield reliable information, and they can be used to reconstruct the biological history of Amerindian populations over the last few centuries.

Body composition in Central Asia populations: Fat patterning variation in the Kazakhs of the Tien Shan mountains and the Uighurs of Semericia.

Eleven anthropometric variables related to fat patterning were analyzed in two populations of Central Asia, the Kazakhs of the Tien Shan mountains (2100 m) and the Uighurs of the Semericia plains. Subjects were healthy unrelated males, 122 Kazakhs and 79 Uighurs, 19-65 years. Comparisons were done with a preliminary analysis of variance and then by covariance analysis, taking into account the influence of age. The Uighurs, independently of age, show higher values than Kazakhs for all of the characteristics related to fat patterning, but principal components analysis suggests a similar somatic structure in the two samples. The presence of lower adiposity in the Kazakhs than in the Uighurs could be related to stress, probably associated with nutrition and lifestyle in a mountain environment. Am. J. Hum. Biol. 10:241-247, 1998. © 1998 Wiley-Liss, Inc.

Body water distribution in highlanders versus lowlanders.

Acute exposure to high altitude produces characteristic changes in body water distribution from which acclimatized individuals seem to be spared. However, it has been suggested that body water distribution may be different in highlanders (HL) as compared to lowlanders (LL). We studied the distribution of total body water (TBW) between extracellular water (ECW) and intracellular water (ICW) in a group of 20 HL (3200 m above sea level) versus one of 20 LL (900 m above sea level). Subjects were matched for ethnic group (Kirghiz), sex (male), weight (Wt), height and body mass index. TBW:Wt and ECW:TBW were not different in HL as compared to LL (mean +/- SD, 58.5 +/- 5.0% versus 56.0 +/- 4.2% and 40.5 +/- 4.2% versus 40.7 +/- 2.2%; p = n.s. for both). This study does not support the hypothesis that body water distribution is different in HL as compared to LL.