Phillip L. Walker

The causes of porotic hyperostosis and cribra orbitalia: A reappraisal of the iron-deficiency-anemia hypothesis

Porosities in the outer table of the cranial vault (porotic hyperostosis) and orbital roof (cribra orbitalia) are among the most frequent pathological lesions seen in ancient human skeletal collections. Since the 1950s, chronic iron-deficiency anemia has been widely accepted as the probable cause of both conditions. Based on this proposed etiology, bioarchaeologists use the prevalence of these conditions to infer living conditions conducive to dietary iron deficiency, iron malabsorption, and iron loss from both diarrheal disease and intestinal parasites in earlier human populations. This iron-deficiency-anemia hypothesis is inconsistent with recent hematological research that shows iron deficiency per se cannot sustain the massive red blood cell production that causes the marrow expansion responsible for these lesions. Several lines of evidence suggest that the accelerated loss and compensatory over-production of red blood cells seen in hemolytic and megaloblastic anemias is the most likely proximate cause of porotic hyperostosis. Although cranial vault and orbital roof porosities are sometimes conflated under the term porotic hyperostosis, paleopathological and clinical evidence suggests they often have different etiologies. Reconsidering the etiology of these skeletal conditions has important implications for current interpretations of malnutrition and infectious disease in earlier human populations.

Sexing skulls using discriminant function analysis of visually assessed traits

The accuracy of sex determinations based on visual assessments of the mental eminence, orbital margin, glabellar area, nuchal area, and mastoid process was tested on a series of 304 skulls of known age and sex from people of European American, African American, and English ancestry as well as on an ancient Native American sample of 156 individuals whose sex could be reliably determined based on pelvic morphology. Ordinal scores of these sexually dimorphic traits were used to compute sex determination discriminant functions. Linear, kth-nearest-neighbor, logistic, and quadratic discriminant analysis models were evaluated based on their capacity to minimize both misclassifications and sex biases in classification errors. Logistic regression discriminant analysis produced the best results: a logistic model containing all five cranial trait scores correctly classified 88% of the modern skulls with a negligible sex bias of 0.1%. Adding age at death, birth year, and population affinity to the model did not appreciably improve its performance. For the ancient Native American sample, the best logistic regression model assigned the correct pelvic sex to 78% of the individuals with a sex bias of only 0.2%. Similar cranial trait frequency distributions were found in same-sex comparisons of the modern African American, European American, and English samples. The sexual dimorphism of these modern people contrasts markedly with that of the ancient Native Americans. Because of such population differences, discriminant functions like those presented in this paper should be used with caution on populations other than those for which they were developed.

An Experimental Study of the Morphological Characteristics of Tool Marks

Experiments were performed to establish correlations between the edge characteristics of a series of tools and the marks they produce when applied to bone. Pressure and angle of application, length of blade, and motion used during the cutting stroke, were found to be important variables that affect the shape of tool marks. Using cross sections of butchering marks from archaeological sites, it was possible to establish associations between various classes of tools and specific tasks.

An archaeological and paleontological chronology for Daisy Cave (CA-SMI-261), San Miguel Island, California.

We provide detailed contextual information on 25 14 C dates for unusually well-preserved archaeological and paleontological remains from Daisy Cave. Paleontological materials, including faunal and floral remains, have been recovered from deposits spanning roughly the past 16,000 yr, while archaeological materials date back to ca. 10,500 BP. Multidisciplinary investigations at the site provide a detailed record of environmental and cultural changes on San Miguel Island during this time period. This record includes evidence for the local or regional extinction of a number of animal species, as well as some of the earliest evidence for the human use of boats and other maritime activities in the Americas. Data from Daisy Cave contribute to a growing body of evidence that Paleoindians had adapted to a wide variety of New World environments prior to 10,000 PB. Analysis of shell-charcoal pairs, along with isotopic analysis of associated marine shells, supports the general validity of marine shell dating, but also provides evidence for temporal fluctuations in the reservoir effect within the Santa Barbara Channel region.

Dental Evidence for Prehistoric Dietary Change On the Northern Channel Islands, California

Santa Rosa Island skeletal collections, dating from between 4000 and 400 B.P., were analyzed for evidence of dental caries. Carious lesions were found to decrease significantly through time, as were sexual differences in caries rates. These trends in dental health appear to reflect changes in diet and sexual division of labor associated with a subsistence shift from the exploitation of roots, tubers, and other cariogenic plant foods to the intensive exploitation of fish. Analysis of dental caries can provide information on prehistoric carbohydrate intake that is unavailable using conventional methods of faunal and artifactual analysis.

Physical Anthropological Evidence for the Evolution of Social Complexity in Coastal Southern California

In this paper we use osteological data to evaluate theories about the rise of chiefdoms in southern California. To do this, we examine skeletal evidence for changes in diet, disease and violence in Santa Barbara Channel area populations. These collections date from before and after the development of large, sedentary coastal villages and a political system that facilitated inter-village economic interaction. Our data show that the health consequences of the development of these chiefdoms are comparable to those seen with the development of complex agricultural societies. They also provide insights into the causes of social complexity in non-agricultural societies.

Environmental Imperatives Reconsidered

Review of late Holocene paleoenvironmental and cultural sequences from four regions of western North America shows striking correlations between drought and changes in subsistence, population, exchange, health, and interpersonal violence during the Medieval Climatic Anomaly (a.d. 800–1350). While ultimate causality is difficult to identify in the archaeological record, synchrony of the environmental and cultural changes and the negative character of many human responses—increased interpersonal violence, deterioration of long‐distance exchange relationships, and regional abandonments—suggest widespread demographic crises caused by decreased environmental productivity. The medieval droughts occurred at a unique juncture in the demographic history of western North America when unusually large populations of both hunter‐gatherers and agriculturalists had evolved highly intensified economies that put them in unprecedented ecological jeopardy. Long‐term patterns in the archaeological record are inconsistent with the predicted outcomes of simple adaptation or continuous economic intensification, suggesting that in this instance environmental dynamics played a major role in cultural transformations across a wide expanse of western North America among groups with diverse subsistence strategies. These events suggest that environment should not be overlooked as a potential cause of prehistoric culture change. The present paper was submitted 16 11 98 and accepted 5 vi 98; the final version reached the Editors office 6 vii 98.

7 – TIME, TEMPERATURE, AND OXYGEN AVAILABILITY: AN EXPERIMENTAL STUDY OF THE EFFECTS OF ENVIRONMENTAL CONDITIONS ON THE COLOR AND ORGANIC CONTENT OF CREMATED BONE

Publisher Summary The color of the cremated bone provides clues to both the condition of the remains at the time of cremation and the environment in which the cremation occurs. As bones go through the four stages of cremation—dehydration, decomposition, inversion, and fusion—their color changes reflect the ongoing chemical processes. Cremation experiments have documented the color changes that occur in both “green” and dried bones as the temperature of the cremation environment increases. The color of the bone cremated at temperatures as low as 200–300 °C begins to change from the ivory or light tan color of unburned bone to dark brown or black as the organic components begin to be carbonized. At somewhat higher temperatures, the bone becomes black or dark gray depending on the duration of the heat exposure as carbonation is completed and the carbonates begin to disappear. At high temperatures of 800 °C or more, the bone becomes “calcined” and the color changes to blue-gray or white. At such high temperatures, the carbon formed from the organic material bonds with oxygen to form CO2, calcinations occur, and the bone salts fuse.

Skeletal evidence for child abuse: a physical anthropological perspective

Analysis of the skeletal remains of abused children can prove challenging for forensic pathologists and radiographers who are inexperienced in the direct examination of bones. In such cases, radiographically invisible skeletal lesions that document a history of trauma can often be identified by a physical anthropologist with appropriate osteological experience. This is illustrated by cases in which skeletal remains of four murdered children and a mentally handicapped adult produced evidence of antemortem trauma and perimortem injuries that was critical in developing murder cases against the assailants. In these cases, well-healed areas of subperiosteal new bone formation were identified that were below the threshold of radiographic detection. Such injuries provide strong evidence for a history of physical abuse.

Age and Sex-Related Variation in Hyoid Bone Morphology

Although the relationship between hyoid bone shape and fracture pattern figures prominently in forensic investigations of strangulation, few quantitative data exist on age and sex differences in hyoid morphology. An image analysis system was used to take a series of 30 measurements on digitized radiographs of 315 hyoid bones from people of known age and sex. The degree of fusion of the greater cornua to the hyoid body was also recorded. Statistical analysis of these data shows that there is a continuous distribution of hyoid bone shapes and the most bones are highly symmetrical. Based on smaller samples, previous researchers have suggested that non-fusion is more common in women than in men. In contrast, our data suggest that men and women have similar non-fusion rates. Analysis of sexual dimorphism shows that the greatest length differences are in the greater cornua. There are also significant sex differences in hyoid shape. For example, the distal ends of the greater cornua of women are significantly longer than those of men.