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

The use of stable carbon isotopes for diet reconstruction is predicated on the assumption that you are what you eat. In other words, the carbon isotopic composition of animal tissues is assumed to be a direct and constant function of the diet. Is this assumption valid? Precise dietary reconstruction requires as accurate knowledge of the isotopic composition of locally available dietary resources, as well as an adequate understanding of the effects of nutrition, environment, and physiology on the diet-tissue function (van der Merwe 1982, 1989; Chisholm 1989; Norr 1990; Matson and Chisholm 1991; Tieszen 1991; Ambrose 1992). There is a systematic but poorly defined difference between the isotopic composition of the consumer tissues and that of the diet (an enrichment factor, expressed as Δ diet-tissue). Given the isotopic composition of a specific tissue, that of the diet or of other tissues may be calculated if the Δ diet-tissue difference factors are known. The dietary proportions of isotopically distinct food resources (e.g., C3 vs C4, or C3 vs marine) have thus been calculated from the δ 13C value of bone collagen (Δ13Cd-co) and bone apatite carbonate (Δ13Cd-ca). Deviations from actual or assumed average δ 13C values for dietary endmembers, and incorrect values for diet-to-tissue isotopic relationships, will lead to errors in the estimation of consumption of specific classes of resources. Experiments and observations designed to determine the diet-to-collagen stable isotope functions (Δ13Cd-co) however, have provided widely different values.

Experimental Evidence for the Relationship of the Carbon Isotope Ratios of Whole Diet and Dietary Protein to Those of Bone Collagen and Carbonate

This study illustrates the potential of small-game data for identifying and dating Paleolithic demographic pulses such as those associated with modern human origins and the later evolution of food-producing economies. Archaeofaunal series from Israel and Italy serve as our examples. Three important implications of this study are that (1) early Middle Paleolithic populations were exceptionally small and highly dispersed, (2) the first major population growth pulse in the eastern Mediterranean probably occurred before the end of the Middle Paleolithic, and (3) subsequent demographic pulses in the Upper and Epi-Paleolithic greatly reshaped the conditions of selection that operated on human subsistence ecology, technology, and society. The findings of this study are consistent with the main premise of Flannery's broad-spectrum-revolution hypothesis. However, ranking small prey in terms of work of capture (in the absence of special harvesting tools) proved far more effective in this investigation of human diet breadth than have the taxonomic-diversity analyses published previously.

The Tortoise and the Hare. Small-Game Use, the Broad-Spectrum Revolution, and Paleolithic Demography.

Although aquatic resources are often seen as central to the development of post-Pleistocene cultural complexity, most models of human evolution have all but ignored the role of aquatic or maritime adaptations during the earlier stages of human history. When did aquatic resources, maritime adaptations, and seafaring first play a significant role in human evolution? I explore this fundamental question by (1) reviewing various theories on the subject; (2) discussing a variety of problems that prevent archaeologists from providing a clear answer; and (3) examining the archaeological record for evidence of early aquatic resource use or seafaring. I conclude that aquatic resources, wherever they were both abundant and relatively accessible, have probably always been used opportunistically by our ancestors. Evidence suggests, however, that aquatic and maritime adaptations (including seafaring) played a significantly greater role in the demographic and geographic expansion of anatomically modern humans after about 150,000 years ago. Another significant expansion occurred somewhat later in time, with the development of more sophisticated seafaring, fishing, and marine hunting technologies.

The Archaeology of Aquatic Adaptations: Paradigms for a New Millennium

The nature of hunter-gatherer mobility strategies--the way in which hunter-gatherers move about a landscape over the course of a year--is discussed, using ethnographic data. Several mobility variables that measure residential and logistical mobility are defined; several environmental variables which measure resource accessibility and resource monitoring costs are also defined. Ethnographic data are used to demonstrate patterning between the nature of mobility strategies and the resource structure of an environment. The data show that the extent to which a group of hunter-gatherers emphasizes residential or logistical mobility is closely related to the structure of resources in their environment.

https://www.jstor.org/stable/pdfplus/3629672.pdf

Hunter-Gatherer Mobility Strategies

The Evolution of Cultural Complexity on the Northwest Coast. The Northwest Coast Cultural Area. History of Archaeological Research. The Initial Colonization of the Northwest Coast. The Emergence of Distinctive Coastal Cultures.The Development of Cultural Complexity. The Achievement of Cultural Complexity. Continuation of the Developed Northwest Coast Pattern. Review of Developments. References. Subject Index.

https://journals.mcmaster.ca/nexus/article/download/164/131

The Prehistory of the Northwest Coast

The transition from Pleistocene to Archaic/Mesolithic is analyzed in broad ecological terms. The trend throughout most of the Pleistocene toward increasing technological diversity is linked to the expectable ecological tendency to increase resource reliability. The advent of culture enabled man to increase resource reliability by diversifying his resource base. Resources were largely of the K-selected type, economical to procure with simple technology but generally subject to overexploitation. By the end of the Pleistocene the diversification of the resource base had reached a maximum in a number of areas, and increased diversity could only be achieved by devising efficient means to exploit r-selected types of resources. It is this shiff in emphasis that characterizes the Archaic/Mesolithic. This change resulted in increases in sedentism, population density, and competition; occupation of new habitats; diversification of resource use in low-resource-density areas and specialization of resource use in area...

Research and Development in the Stone Age: Technological Transitions among Hunter-Gatherers [and Comments and Reply]

Presents a new model for the origins of Basketmaker II culture based on the evolution of maize use, one that focuses on the changes in maize growing rather than on the changes in, or to, the people involved.

The Origins of Southwestern Agriculture

Four separate lines of evidence show that the Cedar Mesa Basketmaker II were dependent on maize horticulture: the settlement pattern of the mesa-top Basketmaker II; stable carbon-isotope analysis of Basketmaker and other skeletal remains from the Cedar Mesa area; and two different analyses of coprolites and midden constituents from the Turkey Pen Cave site (a Basketmaker II site in Grand Gulch, which drains parts of Cedar Mesa) All of these analyses concur with a dependence on maize horticulture for the Cedar Mesa Basketmaker II, a dependence not differing significantly from later Pueblo inhabitants of Cedar Mesa and elsewhere Whether other Basketmaker II variants were as reliant on maize is uncertain, but there are good indications that at least some, and probably all, were By 2,000 years ago the Basketmaker II peoples on Cedar Mesa were not modified hunters and gatherers, but relied on maize

Basketmaker II Subsistence: Carbon Isotopes and Other Dietary Indicators from Cedar

Survey of the Cedar Mesa areaSE Utah, has documented three main periods of Anasazi (ancestral Pueblo Indian) occupation: A. c. 200–400 (Basketmaker II); 650–725 (late Basketmaker III); and 1060–1270 (Pueblo II–III). These are separated by intervals of little or no occupation. Despite marked changes in material culture and architecture generally characteristic of the Anasazi sequence, the three Cedar Mesa occupations display similar patterns of settlement and population density (estimated at 0.75 to 1.5 persons/sq km). The basic adaptation throughout is inferred to have been low-intensity farming, with frequent movement of small, dispersed settlements having low investment in fixed facilities. Departures from this basic pattern are described and evaluated, as are processes possibly responsible for the episodic nature of occupation. These include responses to climatic change and the cumulative effects of shifting cultivation.

R. G. Matson

Papers

The Prehistory of the Northwest Coast

Research and Development in the Stone Age: Technological Transitions among Hunter-Gatherers [and Comments and Reply]

The Origins of Southwestern Agriculture

Basketmaker II Subsistence: Carbon Isotopes and Other Dietary Indicators from Cedar

Adaptational Continuities and Occupational Discontinuities: The Cedar Mesa Anasazi