Cranial variation in European populations: A spatial autocorrelation study at three time periods

Abstract

This study reports on spatial variation of 10 cranial variables in European populations at 3 time periods. Means for these variables, based on 137, 108, and 183 samples from the Early Medieval, Late Medieval, and Recent periods, were subjected to one-dimensional and directional spatial autocorrelation analyses. Significant spatial structure was found for most variables. It becomes more pronounced as time progresses. The spatial patterns are not strongly clinal. Correlograms based on distances computed from all variables are monotonic only to 900, 1,650, and 1,350 km for the three periods. Regional patterns are seen for most variables and become more structured and significant with time. There is little similarity among the correlograms of the variables at any one period and virtually none among periods. Inferences about spatial structure of these populations, based on spatial autocorrelation analysis, suggest a pattern dominated by migration, followed by expansion and admixture rather than selection or chance fluctuations. The patterns of morphometric change seem to reflect the patterns of linguistic change in these areas.

Genetic, geographic, and linguistic distances in Europe.

“…Previous experience with more refined distances based on estimated times of separation had not shown appreciably different results from the trinary distances employed here (32).…”

Regional isolation in the Balkan region: An analysis of craniofacial variation

“…In addition, the improved environment (especially for groups emigrating from preindustrialized nations) would be expected to have a positive effect on secular trends. For example, Rösing and Schwidetzky (1986), as cited by Sokal and Utterschaut (1987), concluded that Medieval craniometric differentiation was a result of culture changes, such as urbanization, and were more significant than climatic adaptation or migration in producing changes in phenotype. However, the present findings concur with the recent study by Sparks and Jantz (2002), which concluded that the environment has a minimal effect on cranial form, and that the primary source of cranial variation is genetic.…”

A Geographic Cline of Skull and Brain Morphology among Individuals of European Ancestry

“…Sokal and Uytterschaut [17] and Sokal et al [18] reported that craniometric variation is spatially structured across Europe but found no clear continental trend and further could not recapitulate a map of Europe. Moreover, these studies found that cranial variation was associated with geography and language family more than time period (Early and Late Middle Ages and a Recent Period).…”

“…Therefore, European cranial diversity has retained some of its spatial patterning for at least 1,500 years. However, the data by Sokal and Uytterschaut [17] and Sokal et al [18] were limited to population averages of only 10 different cranial measurements from populations with non-uniform geographic coverage of Europe. In contrast, our finding of significant skull and brain variation along a NW-SE cline is consistent with genetic and archaeological evidence for range expansions and gene flow due to prehistoric population movements along this geographic axis in Europe.…”

“…We focused on this geographic region because populations in Europe are genetically differentiated in a continuous manner consistent with known historical migrations [14][15][16] , and these populations vary in skull size and shape [8,17,18] . We leveraged two independent data sets in our analyses.…”