Taxonomic, anatomical, and spatio-temporal variations in the stable carbon and nitrogen isotopic compositions of plants from an African savanna

Stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios are commonly used to reconstruct palaeodiets and palaeoenvironments. The method is based on our knowledge of isotopic patterns in plants, which are subject to taxonomic and environmental variability. While previous researchers have addressed isotopic variability amongst plants, no studies have looked extensively at a broad suite of taxa over multiple temporal scales from within the savanna biome so as to provide baseline data for palaeodietary and palaeoenvironmental studies. Here we document variations in the isotopic compositions of plants collected over two years from the Kruger National Park, South Africa, with respect to species and anatomical differences, and the influences of geological substrate and spatio-temporal shifts in climate. Results show that environmentally-induced carbon isotopic variations in plants within this region are generally smaller than 2‰, which is lower than what has been previously reported for plants compared across multiple habitat-types. These data suggest that δ¹³C differences of 2‰ or more (or 1‰ if the diet is predominantly C₄) between animals from a given area reliably indicate real dietary differences. Plant δ¹⁵N values vary greatly between different microhabitats (by up to 4‰), responding to a range of environmental influences that may, in turn, significantly influence variation in animal δ¹⁵N values.     

Presidential Policymaking in Crisis Situations: 9/11 and Its Aftermath

This paper compares the decision-making approaches of two presidents, John F. Kennedy and George W. Bush, in relation to unanticipated international crises. One, President Kennedy, employed a broad body of expert opinion and entertained a wide range of options in meeting the Cuban Missile Crisis of 1963. The actions taken avoided a potential worldwide nuclear war. The other, George W. Bush, consulted only a few, like-minded colleagues and appears to have decided early on that a war directed against Iraq and Saddam Hussein was a necessity. The administration's justifications for the war were difficult to prove and the administration chose an essentially bilateral (as against a multi-lateral) approach. The Iraq War was won fairly easily, although its long-range consequences remain unclear. The two styles of decision-making present polarized approaches to international crisis situation management.     

ELEMENTS OF SKILL: TRAITS,INTELLIGENCES, EDUCATION,AND AGGLOMERATION*

ABSTRACT There are many fundamental issues in regional and urban economics that hinge on worker skills. This paper builds on psychological approaches to learning to characterize the role of education and agglomeration in the skill development process. While the standard approach of equating skill to worker education can be useful, there are important aspects of skill that are missed. Using a measure of skill derived from hedonic attribution, the paper explores the geographic distribution of worker traits, intelligences, and skills and considers the roles of urbanization and education in the skill development process.     

Specialization of ceramic production: A sherd assemblage based analytic perspective

One expectation of emergent complexity is that as ceramic craft specialization increases it is reflected by increasingly homogeneous products due to the modified organization of craft production by specialists. This question has most often been addressed by analysis of sub-sets of larger ceramic assemblages consisting of intact vessels from idiosyncratic contexts. However, excavations often do not yield appropriate whole vessel sub-sets. In order to evaluate the changing context of the organization of ceramic production, we engage a robust methodological approach to the analysis of ceramic sherd assemblages, rather than intact vessels, rooted in cluster analysis but which we rigorously evaluate by other means. We successfully employ this method to assess changes in the organization of ceramic production through a 1000 year sequence leading to the emergence of the Tarascan state, and conclude in this case that no significant reorganization of ceramic production occurred with Tarascan state formation.     

Head Start's Comparative Advantage: Myth or Reality?

In recent years, Head Start's prominent role in preparing low‐income 4‐year‐olds for school has been affected by rapid growth in state‐funded pre‐K programs, some of which are based in public schools. This has led to questions about the comparative advantages of these two approaches to early education. An analysis of data from Tulsa, Oklahoma, indicates that the school‐based pre‐K program is more effective in improving early literacy outcomes, while Head Start is more effective in improving health outcomes. The two programs are comparable with regard to early math learning. Social–emotional effects are more subtle, but the school‐based pre‐K program has demonstrable positive effects, while the Head Start program does not.     

Hunting behavior and Neanderthal adaptability in the Late Pleistocene site of Pech-de-l'Azé I

The late Mousterian of Acheulian tradition (MTA) site of Pech-de-l'Azé 1 shows a very particular stratigraphic sequence characterized by numerous elements not usually found in Mousterian contexts such as avifauna exploitation and the use of hundreds of mineral pigments. Recent zooarchaeological and skeletochronological analyses provide new insights into the evolution of subsistence behaviors and settlement patterns of the Neanderthals that inhabited the shelter. Due to changes in hunting season, Neanderthals adapted their hunting strategies, exploiting various red deer populations which presented very different behavior. The evolution in the seasonal occupation of the shelter may have been the results of major modifications of its (series of roof collapsed) which induced a shrank in inhabitable space., which forced the Mousterians to adjust the way they used the cavity to its characteristics in order to optimize its exploitation. The conclusions underline the excellent adaptability of the Neanderthals to their physical environment.     

The Analysis of Stone Tool Procurement, Production, and Maintenance

Researchers who analyze stone tools and their production debris have made significant progress in understanding the relationship between stone tools and human organizational strategies. Stone tools are understood to be morphologically dynamic throughout their use-lives; the ever-changing morphology of stone tools is intimately associated with the needs of tool users. It also has become apparent to researchers that interpretations of lithic analysis are more productive when the unique contexts and situations for which lithic artifacts were made, used, modified, and ultimately discarded are considered. This article reviews the recent literature on stone tool production with an emphasis on raw material procurement, manufacturing techniques, and tool maintenance processes as they relate to adaptive strategies of toolmakers and users.