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

Criticism and the Growth of Knowledge. Edited by I. Lakatos and A. Musgrave. Pp. viii, 282. £3·50, paperback £1. 1970. (Cambridge University Press.)

In this innovative book, a well-known feminist and sociologist-who is also the founding editor of Gender & Society-challenges our most basic assumptions about gender. Judith Lorber argues that gender is wholly a product of socialization, subject to human agency, organization, and interpretation, and that it is a social institution comparable to the economy, the family, and religion in its significance and consequences. Calling into question the inevitability and necessity of gender, she envisions a society structured for equality, where no gender, racial ethnic, or social class group is allowed to monopolize positions of power.

Paradoxes of gender

Ancient DNA research is revealing a human history far more complex than that inferred from parsimonious models based on modern DNA. Here, we review some of the key events in the peopling of the world in the light of the findings of work on ancient DNA.

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Ancient DNA and the rewriting of human history: be sparing with Occam's razor.

We generated genome-wide data from 69 Europeans who lived between 8,000-3,000 years ago by enriching ancient DNA libraries for a target set of almost 400,000 polymorphisms. Enrichment of these positions decreases the sequencing required for genome-wide ancient DNA analysis by a median of around 250-fold, allowing us to study an order of magnitude more individuals than previous studies and to obtain new insights about the past. We show that the populations of Western and Far Eastern Europe followed opposite trajectories between 8,000-5,000 years ago. At the beginning of the Neolithic period in Europe, ∼8,000-7,000 years ago, closely related groups of early farmers appeared in Germany, Hungary and Spain, different from indigenous hunter-gatherers, whereas Russia was inhabited by a distinctive population of hunter-gatherers with high affinity to a ∼24,000-year-old Siberian. By ∼6,000-5,000 years ago, farmers throughout much of Europe had more hunter-gatherer ancestry than their predecessors, but in Russia, the Yamnaya steppe herders of this time were descended not only from the preceding eastern European hunter-gatherers, but also from a population of Near Eastern ancestry. Western and Eastern Europe came into contact ∼4,500 years ago, as the Late Neolithic Corded Ware people from Germany traced ∼75% of their ancestry to the Yamnaya, documenting a massive migration into the heartland of Europe from its eastern periphery. This steppe ancestry persisted in all sampled central Europeans until at least ∼3,000 years ago, and is ubiquitous in present-day Europeans. These results provide support for a steppe origin of at least some of the Indo-European languages of Europe.

Massive migration from the steppe was a source for Indo-European languages in Europe

Human remains, context, and place of origin for the Salme, Estonia, boat burials

Pitted ware culture: Isotopic evidence for contact between Sweden and Denmark across the Kattegat in the Middle Neolithic, ca. 3000 BC

Archaeological material was initially discovered in 1993, eroding from a small cliff on the north side of the peninsula of Asnaes near the town of Kalundborg in western Sjaelland, Denmark. Ertebolle Excavations in 2007 exposed the Ertebollwe cultural layer and obtained materials to describe the site and its contents before it was destroyed by the sea. The 22 m2 of careful excavations exposed a terrestrial midden deposit and the late Mesolithic cultural layer which had been partially preserved under a raised beach ridge. The flint tools consist primarily of projectile points, flake axes, some distally concave truncated blade knives, and a very few scrapers. There were large numbers of well-preserved faunal remains including bone fishhooks and preforms, seal bones, large bird bones, and an extraordinary amount of fish bone. A quantity of pottery was recovered in the excavations as well, including both pointed-bottom vessels and oval lamps in different sizes from the late Mesolithic and several examples of what are probably Early Neolithic ceramics. The rich occupation layer with its diverse artifactual content, including a fragment of a human jaw, documents a sizable residential settlement on the north coast of the Asnaes peninsula.

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T. Douglas Price

Papers

Human remains, context, and place of origin for the Salme, Estonia, boat burials

Pitted ware culture: Isotopic evidence for contact between Sweden and Denmark across the Kattegat in the Middle Neolithic, ca. 3000 BC

Asnæs Havnemark: a late Mesolithic Ertebølle coastal site in western Sjælland, Denmark

Isotopic Evidence of the African Origins and Diet of Some Early Inhabitants of Campeche, Mexico

The Archaeology of the Future