Boas's Changes in Bodily Form: The Immigrant Study, Cranial Plasticity, and Boas's Physical Anthropology

In two recent articles, we and another set of researchers independently reanalyzed data from Franz Boas's classic study of immigrants and their descendants. Whereas we confirm Boas's overarching conclusion regarding the plasticity of cranial form, Corey Sparks and Richard Jantz argue that Boas was incorrect. Here we attempt to reconcile these apparently incompatible conclusions. We first address methodological differences between our reanalyses and suggest that (1) Sparks and Jantz posed a different set of questions than we did, and (2) their results are largely consistent with our own. We then discuss our differing understandings of Boas's original argument and of the concept of cranial plasticity. In particular, we argue that Sparks and Jantz attribute to Boas a position he explicitly rejected. When we clarify Boas's position and place the immigrant study in historical context, Sparks and Jantz's renalysis supports our conclusion that, on the whole, Boas got it right. [Keywords: Franz Boas, plasticity, anthropometry, heritability, immigrant study]     

Changing Times, Changing Faces: Franz Boas's Immigrant Study in Modern Perspective

Franz Boas's study of the changes in bodily form of descendants of immigrants has stood for over ninety years as proof of environmental influences on cranial form. Recent reanalysis of his data have shown differing interpretations of the importance of his findings. Here, we explore the historical, political, and social setting of the study that could have led Boas to overstate the importance of his findings. We also include a discussion of the issue at large with respect to the study of modern and prehistoric human variation. Given the current state of population research using craniometric data we conclude, as many of Boas's early criticism have, that while some of the changes observed by Boas have statistical credibility, they generally lack biological meaning when considered in the scope of the degree of modern human variation. [Keywords: plasticity, immigration, craniometries, cranial index, human variation]     

Reanalysis of Vernalization Data of Wheat and Carrot

Vernalization is an important determinant of the growth, development,and yield of biennial and perennial crops. Accurate simulationof its response to temperature is thus an important componentof successful crop systems modelling. Vernalization has a lowoptimum temperature compared to other temperature responsesof plants, and thus may be difficult to treat using expressionsthat are appropriate for other plant processes. This paper examinesthe application of a simple equation that has been used forother processes. It reads as v=V_max(T_max-T_{Tmax- Topt} ) (T_Topt)^{T_optTmax-T_opt}, where v is thedaily rate of vernalization progress at temperature T, T_optandT_maxare the optimum and maximum temperatures for vernalization,respectively, andV_max is the maximum daily rate of vernalization(the inverse of the minimum number of days required to completevernalization), which occurs at T_opt. The model was appliedto published vernalization data for wheat and carrot. The fitsto data were good (adjusted R²for wheat of 0.94, for carrot0.98), with estimatedT_opt and T_maxbeing 5.7±0.5 and 21.3±1.4°C, respectively, for wheat ‘Norin 27’ and 6.6±0.2and 14.1±0.3 °C for carrot ‘ Chantenay RedCored’. The estimated parameters, in particular the highT_maxfor wheat, were close to those reported using differentanalytical approaches. It was suggested that the function wouldbe useful for summarizing vernalization data, and that its usewould avoid the abrupt changes that are inevitable when differentlinear relationships are used for part of the overall response.It was also suggested the high T_maxshould be taken into accountwhen interpreting data obtained with wheat grown under warmconditions. Copyright 1999 Annals of Botany Company Plant, vernalization, temperature response, modelling, wheat (Triticum aestivum L.), carrot (Daucus carota L.).     

Neurochemistry,Neuropathology, and Heredity in SAMP8: A Mouse Model of Senescence

The SAMP8 strain spontaneously develops learning and memory deficits with characteristics of aging, and is a good model for studying the mechanism of cognitive dysfunction with age. Oxidative stress occurs systemically in SAMP8 from early on in life and increases with aging. Neuropathological changes such as the deposition of Aβ, hyperphosphorylation of tau, impaired development of dendritic spines, and sponge formation, and neurochemical changes were found in the SAMP8 brain. These changes may be partially mediated by oxidative stress. Oxidative damage is a major factor in neurodegenerative disorders and aging. A decline in the respiratory control ratio suggesting mitochondrial dysfunction was found in the brain of SAMP8. The rise in oxidative stress following mitochondrial dysfunction may trigger neuropathological and neurochemical changes, disrupting the development of neural networks in the brain in SAMP8. Special issue article in Honour of Dr. Akitane Mori.     

Variation among North Amerindians: analysis of Boas's anthropometric data.

In the late nineteenth century Franz Boas was responsible for assembling anthropometric data from North Amerindians. Approximately 15,000 subjects were measured, but the data have never been systematically analyzed. Here we describe our efforts to develop a computerized database from Boas's data and present the first systematic analysis of these data. In addition to a general analysis of North Amerindian anthropometric variation, we also present a more detailed analysis of anthropometric variation among tribes located in the American Northwest. In the general analysis we find that anthropometric variation is strongly patterned along geographic lines. We examine geographic and language patterning by grouping tribes by culture area and language phylum. Both have high explanatory power, culture area being the higher. The Northwest analysis shows that both language and geographic location are important in explaining anthropometric variation.     

Cranial muscle markers: A preliminary examination of size, sex, and age effects

Most muscle marker research consists of post-cranial analyses, but some researchers examine crania to reconstruct activities. Regardless of bones examined, anthropologists know of some of the complexities surrounding muscle marker development. Here, posterior cranial muscle markers are analyzed to determine whether they are useful in reconstructing activities by examining effects that may hinder reconstructions. Additionally, upper limb muscle markers and humeral cross-sectional robusticity variables are correlated with cranial muscle markers to determine if robust individuals are generally robust due to the synergistic effects of muscle use.Cranial muscle markers of 65 prehistoric California Amerinds are scored using a five-point observer rating scale. Body mass is calculated from femoral head size; maximum cranial length and breadth are measured with a spreading caliper; and age and sex are determined through standard procedures. Upper limb muscle markers are scored on seven sites using two dimensions within a seven-point scale. Cross-sectional properties are calculated from biplanar humeral radiographs. Aggregates are created for cranial muscle markers, upper limb muscle markers, and cross-sectional robusticity.Cranial muscle markers correlate significantly with cranial length, r=0.25 and cross-sectional robusticity of humerus, r=0.29; P’s<0.05. All variables differed between sexes (Mann-Whitney=31.00-307.50, P’s<0.01). Results imply that some differences in cranial muscle markers are related to size; however, individuals with well-developed cranial muscle markers have greater upper limb robusticity possibly due to activity patterns. Sex differences remained after size controls and may relate to activity differences.     

Discrepancy between Cranial and DNA Data of Early Americans: Implications for American Peopling

Currently, one of the major debates about the American peopling focuses on the number of populations that originated the biological diversity found in the continent during the Holocene. The studies of craniometric variation in American human remains dating from that period have shown morphological differences between the earliest settlers of the continent and some of the later Amerindian populations. This led some investigators to suggest that these groups—known as Paleomericans and Amerindians respectively—may have arisen from two biologically different populations. On the other hand, most DNA studies performed over extant and ancient populations suggest a single migration of a population from Northeast Asia. Comparing craniometric and mtDNA data of diachronic samples from East Central Argentina dated from 8,000 to 400 years BP, we show here that even when the oldest individuals display traits attributable to Paleoamerican crania, they present the same mtDNA haplogroups as later populations with Amerindian morphology. A possible explanation for these results could be that the craniofacial differentiation was a local phenomenon resulting from random (i.e. genetic drift) and non-random factors (e.g. selection and plasticity). Local processes of morphological differentiation in America are a probable scenario if we take into consideration the rapid peopling and the great ecological diversity of this continent; nevertheless we will discuss alternative explanations as well.