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

Bones of recent mammals in the Amboseli Basin, southern Kenya, exhibit distinctive weathering characteristics that can be related to the time since death and to the local conditions of temperature, humidity and soil chemistry. A categorization of weathering characteristics into six stages, recognizable on descriptive criteria, provides a basis for investigation of weathering rates and processes. The time necessary to achieve each successive weathering stage has been calibrated using known-age carcasses. Most bones decompose beyond recognition in 10 to 15 yr. Bones of animals under 100 kg and juveniles appear to weather more rapidly than bones of large animals or adults. Small-scale rather than widespread environmental factors seem to have greatest influence on weathering characteristics and rates. Bone weathering is potentially valuable as evidence for the period of time represented in recent or fossil bone assemblages, in- cluding those on archeological sites, and may also be an important tool in censusing populations of animals in modern ecosystems.

Taphonomic and Ecologic Information Form Bone Weathering

Hominid behaviour and the earliest occupation of Europe: an exploration

This paper proposes that complex projectile weaponry was a key strategic innovation driving Late Pleistocene human dispersal into western Eurasia after 50 Ka. It argues that complex projectile weapons of the kind used by ethnographic hunter-gatherers, such as the bow and arrow, and spearthrower and dart, enabled Homo sapiens to overcome obstacles that constrained previous human dispersal from Africa to temperate western Eurasia. In the East Mediterranean Levant, the only permanent land bridge between Africa and Eurasia, stone and bone projectile armatures like those used in the complex weapon systems of recent humans appear abruptly ca 45–35 Ka in early Upper Paleolithic contexts associated with Homo sapiens fossils. Such artifacts are absent from Middle Paleolithic contexts associated with Homo sapiens and Neandertals. Hypotheses concerning the indigenous vs. exogenous origins of complex projectile weaponry in the Levant are reviewed. Current evidence favors the hypothesis that complex projectile technology developed as an aid to ecological niche broadening strategies among African populations between 50–100 Ka. It most likely spread to western Eurasia along with dispersing Homo sapiens populations. Neandertals did not routinely deploy projectile weapons as subsistence aids. This puzzling gap in their otherwise impressive record for survival in some of the harshest environments ever occupied by primates may reflect energetic constraints and time-budgeting factors associated with complex technology.

Complex Projectile Technology and Homo sapiens Dispersal into Western Eurasia

Ebb and flow or regional extinctions? On the character of Neandertal occupation of northern environments

Limiting factors on early modern human dispersals: The human biogeography of late Pleniglacial Europe

New dating of several key sites in eastern Central Europe refines our view of human presence there around the Last Glacial Maximum. The author shows that, with the advancing Ice Age, this part of Europe was abandoned later than the west, and a critical environmental factor was increasing aridity rather than the dropping temperatures.

Eastern Central Europe during the Pleniglacial

Recent studies indicate high energetic requirements for Neanderthals. The high requirements have behavioural implications, for example, related to the use of the landscape. Using a simple central place foraging model I show that Neanderthal energetic requirements can explain the main characteristics of the Middle Palaeolithic archaeological record, from the lack of features at sites to the limits of the Neanderthal range.

Neanderthal energetics and spatial behaviour

An Energetics Perspective on the Neandertal Record

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Alexander Verpoorte

Papers

Limiting factors on early modern human dispersals: The human biogeography of late Pleniglacial Europe

Eastern Central Europe during the Pleniglacial

Neanderthal energetics and spatial behaviour

An Energetics Perspective on the Neandertal Record

Places of Art, Traces of Fire: A Contextual Approach to Anthropomorphic Figurines in the Pavlovian