The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. 
The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. 
The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. 
The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

Citation classic - optimal foraging - a selective review of theory and tests

Time is divided by geologists according to marked shifts in Earth's state. Recent global environmental changes suggest that Earth may have entered a new human-dominated geological epoch, the Anthropocene. Here we review the historical genesis of the idea and assess anthropogenic signatures in the geological record against the formal requirements for the recognition of a new epoch. The evidence suggests that of the various proposed dates two do appear to conform to the criteria to mark the beginning of the Anthropocene: 1610 and 1964. The formal establishment of an Anthropocene Epoch would mark a fundamental change in the relationship between humans and the Earth system.

Defining the Anthropocene

Morphometric tools for landmark data: geometry and biology

Animal Bones in Archaeology Book of Notes and Drawings for Beginners. By Michael L. Ryder. (Mammal Society Handbooks.) Pp. xxiv + 65. (Blackwell (Scientific): Oxford and Edinburgh. Published for the Mammal Society, 1969.) 17s.

Digging up Bones

Different Andean societies underwent processes of expansion and collapse during propitious or adverse climate conditions, resource boost or depletion along with population variations. Previous studies have emphasized that demographic collapses of polities in the Central Andes Area were triggered by warfare and the negative impacts of fluctuating climate (droughts) on crop productivity. Nevertheless, the interactions between climatic variability, demography and warfare have been less thoroughly evaluated. We develop population dynamic models to test feedback relationships between population growth, climate change and warfare in the Central Andes, where considerable regional hydroclimate variations have occurred over a millennium. Through population models, we found out that the rise and demise of social polities in the northern coast of the Central Andes appear to be a consequence of climate change. In contrast, for the highlands of Peru and the Titicaca basin, population models suggest that warfare intensity has a negative effect on population growth rates.

1000 years of population, warfare, and climate change in pre-Columbian societies of the Central Andes

Se propone que las relaciones sociales entre areas nucleares o areas culturales centrales, escenarios de formaciones sociales degran escala y las zonas extranucleares (semiperiferias, periferias y ultraperiferias) fueron complejas y no pueden ser descritas yexplicadas con los paradigmas unilineales y unidireccionales del neoevolucionismo. La realidad de la region andina antigua ymoderna muestra una gran variabilidad en los grados de negociacion, aceptacion, resistencia y tolerancia entre ambos sistemassociales (centro y periferia). Por otro lado, las propias sociedades locales muestran variados procesos de cambio y continuidad,influenciados no solo por la gran diversidad ecologica, en terminos de produccion y predictibilidad, sino tambien por los propi osintereses sociales de las comunidades y sus lideres a traves del tiempo.

Áreas periféricas y nucleares. contextos de interacciones sociales complejas y multidireccionales* peripherical and core areas. contexts for complex and multidirectional social interactions

Three regional rock art studies undertaken in the southern hemisphere (northwest central Queensland in Australia, Lluta Valley in northern Chile and Quebrada de Humahuaca in Northwest Argentina) are analysed. Based on the relationships between rock art and other aspects of the physical, social and chronological context of its production, we show the articulation between the production of rock art and past social strategies. The three examples demonstrate many consistencies in the way rock art has been utilised in arid environments while also identifying regionally distinct variations in technique and function. In each of the arid regions, competition arose for limited and valued resources. In each example, the production of rock art was used as a powerful tool to negotiate newly arising circumstances in order to ensure predictable and desirable economic and social outcomes for the artists’ group. The methods and form used to achieve these outcomes varied in each case study, because of the availability of materials for art production, the topography and environmental conditions in each specific area, particular cultural preferences and the ways in which people utilised art. In northwest central Queensland the rock art assemblage was employed for the negotiation of group identity at several levels. In the Lluta Valley, the geoglyphs embody social, political and economical aspirations, being produced as a means of legitimating the access of lama caravans to the coast and its resources. In the Quebrada de Humahuaca increased competition for resources led to the production of different rock art assemblages; the herders produced panels that played roles such as marking grazing territories, commemorating past events and most significantly, as part of the ritual life of the herders.

MorE tHaN tHE MotiFS: tHE arCHaEoloGiCal aNalYSiS oF roCK art iN arid rEGioNS oF tHE SoUtHErN HEMiSPHErE 1 MÁS QUE MOTIVOS: EL ANÁLISIS ARQUEOLÓGICO DEL ARTE RUPESTRE EN REGIONES ÁRIDAS DEL HEMISFERIO SUR

Calogero M. Santoro

Papers

1000 years of population, warfare, and climate change in pre-Columbian societies of the Central Andes

Áreas periféricas y nucleares. contextos de interacciones sociales complejas y multidireccionales* peripherical and core areas. contexts for complex and multidirectional social interactions

MorE tHaN tHE MotiFS: tHE arCHaEoloGiCal aNalYSiS oF roCK art iN arid rEGioNS oF tHE SoUtHErN HEMiSPHErE 1 MÁS QUE MOTIVOS: EL ANÁLISIS ARQUEOLÓGICO DEL ARTE RUPESTRE EN REGIONES ÁRIDAS DEL HEMISFERIO SUR

A la admirable maría victoria castro rojas, in memoriam

Chinchorro fibre management in the Atacama Desert and its significance for understanding Andean textilization processes