Head form and climatic stress

Beals, Kenneth L.

doi:10.1002/ajpa.1330370111

Cited by 81 publications

(57 citation statements)

References 3 publications

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“…Etler (1994: p. 112a) suggests the possibility that H. erectus from Zhoukoudian represents a "cold-adapted racial variation within the population structure of middle Pleistocene east Asia." Beals (1972) and Beals et al (1983) have suggested that climate can influence the shape of the skull, and contend that data shows a trend toward brachycephaly in colder areas. Data collected from H. erectus crania are consistent with this conclusion (Beals et al, 1983).…”

Section: Discussionmentioning

confidence: 99%

A multivariate examination of the Hexian calvaria

Durband

Kidder

Jantz

2005

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The Homo erectus calvaria from Hexian, Anhui province, China is an important component of the fossil sample from East Asia. This specimen is the most complete Chinese H. erectus cranium found outside Zhoukoudian. Previous work has shown that the fossil crania from Zhoukoudian exhibit a unique metric pattern not seen in specimens from Africa or Indonesia. Multivariate statistics that assess the statistical significance of distances have not been used to compare the Hexian cranium to other relevant fossils, and this has hampered our appreciation of the pattern and magnitude of variation in the Chinese fossil record. This study involves the use of Mahalanobis distances to examine the variation present in a large sample of Homo erectus crania. Two separate examinations utilizing up to 7 measurements on 15 crania were performed to maximize the number of available specimens. Random expectation statistics were then used to test for significance between these fossils. Our results highlight clear metric dissimilarities between the Hexian calvaria and the fossils from Zhoukoudian. These metric patterns also separate Hexian from Zhoukoudian V, a skull with which it shares some more modern non-metric features. Our results indicate a greater degree of variation in the human fossil sample from China than has previously been recognized.

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Section: Discussionmentioning

confidence: 99%

A multivariate examination of the Hexian calvaria

Durband

Kidder

Jantz

2005

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“…The presence of a neutral signal in craniodental traits may be seen as largely unexpected, since many studies had previously focused on the effects of selective pressures and developmental plasticity in creating cranial shape variation (e.g., Beals 1972;Beals et al 1983Beals et al , 1984Franciscus and Long 1991).…”

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confidence: 99%

Human Pelvis and Long Bones Reveal Differential Preservation of Ancient Population History and Migration Out of Africa

2012

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One of the main events in the history of our species has been our expansion out of Africa. A clear signature of this expansion has been found on global patterns of neutral genetic variation, whereby a serial founder effect accompanied the colonization of new regions, in turn creating a within-population decrease in neutral genetic diversity with increasing distance from Africa. This same distinctive pattern has also been described for cranial and dental morphological variation in human populations distributed across the globe. Here, we used a data set of postcranial linear measurements for 30 globally distributed human populations, and a climatic data set of minimum annual temperature, maximum annual temperature, and precipitation in order to separate for the first time the relative effect of neutral demographic processes and climatic selection on four long (limb) bones (femur, tibia, radius, and humerus) versus the pelvic bones of the human appendicular skeleton. We implemented a stepwise regression procedure in which phenotypic variance is assumed to be affected by the iterative founder events that accompanied human expansion from Africa, as well as by climate. This model included, as independent factors, geographic distance from central Africa, the three climatic variables, and all possible interactions between the three climatic variables. We excluded all nonsignificant factors by backward stepwise elimination with the aim of identifying the minimal model significantly explaining variation in the phenotypic data. Our results indicate a sharp difference in the way the pelvis and the limb bones reflect the neutral signature of the out-of-Africa expansion. Consistent with previous analyses of the cranium and dentition, pelvic shape variation shows a significant within-population decrease with increasing distance from Africa. However, no such pattern could be found in the long bones. Rather, in the case of both the tibia and the femur, a significant relationship between population-level variance and minimum temperature was demonstrated. Hence, in the case of these limb bones, it is probable that the effects of climatic selection have obliterated the demographic signature of human dispersal from Africa. Our finding that pelvic variation exhibits the neutral effects of demographic history suggests that consideration of this skeletal element might be used to shed light on factors of human population history, just as the cranium has done. KeywordsSerial Founder Effect, Out Of Africa, Anatomically Modern Humans, Pelvis Cover Page FootnoteWe are grateful to Brendon Billings of the Medical School of the University of Witwatersrand and Dr. Ogeto Mwebi of the National Museum of Kenya for allowing access to collections and general assistance. We are also especially grateful to Dr. Benjamin Auerbach for generously making his data freely available. We thank Franz Manni and three anonymous reviewers for constructive comments. This study was funded by Sigma Xi, The Abstract One of the main events in the history of our...

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“…inter-group correlations, between cranial measurements and environmental variables in modern human populations because contemporary geographic variations in cranial measurements may be the results of adaptation to some environmental factors. Beals (1972), Guglielmino-Matessi et al (1979), Beals et al (1983Beals et al ( , 1984, Mizoguchi (1985), Kouchi (1986), and others, have investigated ecological correlations between the head shape and climatic variables, and confirmed that brachycephalic people live in higher latitudes or colder regions.…”

Section: Introductionmentioning

confidence: 86%

Ecological correlations between neurocranial and limb bone measurements: toward the solution of the brachycephalization problem

Mizoguchi

2007

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As a step toward clarifying the causes of brachycephalization, ecological correlations, i.e. inter-group correlations, between neurocranial and limb bone measurements were investigated using Spearman's rank correlation coefficient on the basis of 24 male and 23 female samples from prehistoric, historic and modern Japanese populations. It was found that there were significant ecological correlations common to males and females between cranial length and some thickness measurements of the radius, ulna, femur, and tibia, but no consistent correlations between cranial breadth and any limb bone measurements. These findings are compatible with one of the tendencies seen in previous intra-group analyses, and suggest that brachycephalization or dolichocephalization associated with cranial length may have been partly caused by diachronic change in the degree of development of skeletal muscles. This, in turn, may have occurred in accordance with diachronic changes in quality and quantity of available nutrition, physical activity, etc.

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Head form and climatic stress

Cited by 81 publications

References 3 publications

A multivariate examination of the Hexian calvaria

A multivariate examination of the Hexian calvaria

Human Pelvis and Long Bones Reveal Differential Preservation of Ancient Population History and Migration Out of Africa

Ecological correlations between neurocranial and limb bone measurements: toward the solution of the brachycephalization problem

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