Archaeological Amerindian and Eskimo cranioskeletal size variation along coastal western North America: relation to climate, the reconstructed diet high in marine animal foods, and demographic stress

Abstract

A quantitative bioenvironmental study of cranioskeletal size has been made of a latitude‐ordered sequence of 14 series of adult skeleton sets (N=305): the archaeological remains of aboriginal maritime peoples inhabiting the west coast of North America between southern California and the Arctic. Of eight osteometric parameters of cranioskeletal size developed, the most important are partial skeleton volume (PSK) and cranial capacity (CC); and the principal bone‐affecting environmental factors are the northerly climate (CLIM2c), the reconstructed diet deficient in calcium and overabundant in animal foods and vitamin D (DIET3c), and demographic stress (DSg). Prior research has demonstrated that cranioskeletal size increases with geographical latitude and decreases under dietary calcioprivation and unphysiologically high birth rates. Upon linear multifactorial statistical analysis our main finding, limited to the Amerindian subsequence (n=11 series) from the Santa Barbara Channel, the San Francisco Bay Region and the Northwest Coast, is that PSK and CC vary in direct proportion to CLIM2c, and inversely with DIET3c and DSg. Controlling for the latter two osteoantitrophic factors, coastal Amerindian female PSK rises by 9% between 34 and 54°N latitude, CC by 5%; and the male incremental rates are somewhat higher, 13 and 10%, respectively. This newly discovered climate‐dependent race cline, an example of Bergmann's Rule, is interpreted as factual evidence of a mid‐Wisconsin or earlier arrival date for the first Palaeoindians. Cranioskeletal size of the very small (n=3 series) Western Eskimo subsequence approximates the northernmost values of the coastal Amerindian distribution. © 1998 John Wiley & Sons, Ltd.

A Reassessment of Bergmann's Rule in Modern Humans

“…Conversely, the results of the present study cast doubt on Ivanhoe et al 's [23] and Fukase et al 's [20] claims to have found evidence that regional body size co-varies with temperature in the manner predicted by Bergmann's rule. Ivanhoe et al [23] investigated the effects of latitude and nutrition on cranial capacity and a proxy for body size–partial skeletal volume–among indigenous groups along the western coast of North America.…”

“…Neither the sample used by Ivanhoe et al [23] nor the one employed by Fukase et al [20] meets the two criteria set out above. The groups included in Ivanhoe et al 's [23] sample are distributed across approximately 34 degrees of latitude. The groups in Fukase et al 's [20] sample are even more narrowly distributed.…”

“…Over the last 60 years, a number of researchers have sought to determine whether regional groups conform to Bergmann's rule. Some of these workers have claimed to find evidence for Bergmann's rule in their samples [20], [23]. Others have failed to find a significant correlation between body size and temperature within regions [17], [19], [22], [33].…”

“…Ivanhoe et al [23] investigated the effects of latitude and nutrition on cranial capacity and a proxy for body size–partial skeletal volume–among indigenous groups along the western coast of North America. They found that both cranial capacity and partial skeletal volume increase with latitude, and concluded from this that Bergmann's rule operated among the groups.…”

“…There is also ambiguity regarding which variable should be used to represent temperature. Latitude has been employed in some studies [7], [20]; mean annual temperature in others [8], [9], [10], [12], [17], [21]; and both latitude and mean annual temperature in still others [22], [23]. Given these uncertainties, we opted to use multiple body size variables and two temperature variables.…”