Methods of soil P analysis in archaeology

Phosphorus (P) is unique among the elements in being a sensitive and persistent indicator of human activity. It has long been of interest to archaeologists because of its potential to inform them about the presence of past human occupation and to offer clues regarding the type and intensity of human activity. A wide variety of methods have been developed in both soil science and in archaeology to extract and measure soil P, resulting in a tremendous amount of data and a wide array of interpretations, but also considerable confusion over appropriateness of methods and terminology. The primary purpose of this paper is to address these issues by clarifying soil P analyses. Anthropogenic additions of phosphorus to the soil come from human refuse and waste, burials, the products of animal husbandry in barns, pens, and on livestock paths, or intentional enrichment from soil fertilizer. Once added to the soil, phosphorus in its common form as phosphate is stable and generally immobile in soils. Soil P comes in many forms, organized for the purposes of this paper on the basis of extraction and measurement procedures as (1) extraction for available P (Pav); (2) portable field techniques (the spot test or ring test); (3) chemical digestion of a soil sample for total P (Ptot); (4) extractions of inorganic P (Pin) for fractionation studies and extractions to look at individual compounds of P; (5) measurements of organic P (Porg); and (6) extractions for total elemental analysis. To compare the suitability of various extractants as the “best” indicator of human input and activity we subjected samples from three very different archaeological sites (Lubbock Lake, TX; Hulburt Creek, IA; British Camp, WA) to four methods of soil P extraction: perchloric acid digestion (Ptot), sulfuric–nitric acid extraction Ptot), hydrochloric acid extraction after ignition (Pin), and citric acid extraction (Pav). Further, methods of measurement were compared via colorimetry vs. Inductively Coupled Plasma (ICP) spectrometry, and the two methods of supposed “total P” were both measured via ICP. In general, the stronger extractants yielded more soil P, but the result are not clear-cut. Likely variables include the intensity of occupation, nature of the parent material, and postdepositional weathering (e.g., the addition of dust).     

Would North American Paleoindians have Noticed Younger Dryas Age Climate Changes?

Paleoindian groups occupied North America throughout the Younger Dryas Chronozone. It is often assumed that cooling temperatures during this interval, and the impact these would have had on biotic communities, posed significant adaptive challenges to those groups. That assessment of the nature, severity and abruptness of Younger Dryas changes is largely based on ice core records from the Greenland ice sheet where changes were indeed dramatic. This paper reviews climatic and environmental records from this time period in continental North America. We conclude that, on the Great Plains and in the Rocky Mountains, conditions were in reality less extreme. It therefore follows that conditions during the Younger Dryas interval may not have measurably added to the challenge routinely faced by Paleoindian groups who, during this interval, successfully (and perhaps rapidly) dispersed across the diverse habitats of Late Glacial North America.     

Earth science and archaeology

Rapp, George, Jr., and John A. Gifford. eds. Archaeological Geology. New Haven: Yale University Press, 1985. xvii + 435 pp. including figures, chapter references, appendix, and index. $35.00 cloth.

Stein, Julie K., and William R. Farrand, eds. Archaeological Sediments in Context. Orono: University of Maine, Center for the Study of Early Man, Peopling of the Americas Edited Volume Series 1, 1985. xi + 147 pp. including figures, chapter references, and index. $19.00 paper.     

Prologue to Uses of Chemical Residues to Make Statements About Human Activities

Soil chemistry provides the potential for interpreting the archaeological record without necessarily resorting to artifacts, historical documents, ethnoarchaeological observations, or experiments. The range of studies incorporating new technological developments, such as mass spectrometry and multi-element analyses, for analyzing and interpreting the chemical residues found at archaeological sites or modern contexts are increasing in the literature. However, the dilemmas of interpretation concentrate on evaluating the advantages and disadvantages of different techniques. Analytical approaches to how scientists make use of chemical residues to make statements about the past, discussed here, expand the potential of the breadth of techniques to investigate daily life activities and further our understanding of the materiality of social life.     

Population Affinities of the Jebel Sahaba Skeletal Sample: Limb Proportion Evidence

The Lower Nubian Epipaleolithic site of Jebel Sahaba (Sudan) was discovered in 1962. From 1962 to 1966, a total of 58 intentionally buried skeletons were uncovered at the site. Diagnostic microliths indicative of the Qadan industry as well as the site's geology suggest an age of 14–12 ka for these burials. In this study, the body proportions of the Jebel Sahaba sample are compared with those of a large (max N = 731) sample of recent human skeletons from Europe, Africa and circumpolar North America, as well as to terminal Pleistocene ‘Iberomaurusian’ skeletons from the Algerian sites of Afalou‐Bou‐Rhummel and the later Capsian‐associated Ain Dokhara specimen, as well as Natufian skeletons from the southern Levantine site of El Wad. Bivariate analyses distinguish Jebel Sahaba from European and circumpolar samples, but do not tend to segregate them from recent North or sub‐Saharan African samples. Multivariate analyses (principal components analysis, principal coordinates analysis with minimum spanning tree and neighbour‐joining cluster analyses) indicate that the body shape of the Jebel Sahaba humans is most similar to that of recent sub‐Saharan Africans and different from that of either the Levantine Natufians or the northwest African ‘Iberomaurusian’ samples. Importantly, these results corroborate those of both Irish and Franciscus, who, using dental, oral and nasal morphology, found that Jebel Sahaba was most similar to recent sub‐Saharan Africans and morphologically distinct from their penecontemporaries in other parts of North Africa or the groups that succeed them in Nubia. Copyright © 2013 John Wiley & Sons, Ltd.     

Set the junta free: Pre-transitional justice in Myanmar's democratisation

Myanmar is in political deadlock. In part, this is because the opposition has not confronted problems of transitional justice, notably how to deal with members of the military junta who have participated in gross human rights violations. There are therefore few incentives for the ruling generals to consider talking about change. To tackle this problem, the article develops a model of pre-transitional justice that is focused on the critical ‘torturer problem’. It is also informed by recent developments in international criminal law, and by the spread of truth commissions and lustration systems. The integrated reconciliatory model that results is suitable for political negotiation, capable of generating discontinuities with an authoritarian past, and legally and technically feasible. Applying it to Myanmar, the article holds that qualified amnesty is necessary for political reform.     

Optically stimulated luminescence dating of Southern High Plains archaeological sites

The Southern High Plains of North America is rich in archaeological sites, but many are not well constrained chronologically, owing to a lack of material for radiocarbon dating. A program of optically stimulated luminescence (OSL) dating, applying mainly single-grain analyses, was therefore initiated. Many samples have independent age estimates from radiocarbon to check the OSL results, but OSL age estimates are also provided for those sites that otherwise lack secure chronological control. Sediment samples for OSL were obtained primarily from Paleoindian and Archaic localities, though include deposits of more recent age. Through the analysis of single grains, equivalent dose—the numerator of the age equation—is evaluated independently on numerous grains. The distribution of these values is relatively broad for some samples, and this is attributed to post-depositional mixing. Mixing is also evident in some samples with more narrow distributions. Selecting portions of the mixed distributions for age determination allows more accurate dating for some samples, but the nature of the distributions limits the resolution on others, conclusions that cannot be as easily drawn from multi-grain analysis. Where independent age control is available, most OSL results broadly conform; however, some samples show discrepancies that are not readily explained, but may relate to association or dose rate problems. This underscores the desirability of obtaining where possible suites of chronological evidence.