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

Trust: The Social Virtues and the Creation of Prosperity

Not by Genes Alone: How Culture Transformed Human Evolution

Effect sizes are underappreciated and often misinterpreted—the most common mistakes being to describe them in ways that are uninformative (e.g., using arbitrary standards) or misleading (e.g., squa...

https://journals.sagepub.com/doi/pdf/10.1177/2515245919847202

Evaluating Effect Size in Psychological Research: Sense and Nonsense:

Human social interaction is strongly shaped by other-regarding preferences, that is, a concern for the welfare of others. These preferences are important for a unique aspect of human sociality-large scale cooperation with genetic strangers-but little is known about their developmental roots. Here we show that young children's other-regarding preferences assume a particular form, inequality aversion that develops strongly between the ages of 3 and 8. At age 3-4, the overwhelming majority of children behave selfishly, whereas most children at age 7-8 prefer resource allocations that remove advantageous or disadvantageous inequality. Moreover, inequality aversion is strongly shaped by parochialism, a preference for favouring the members of one's own social group. These results indicate that human egalitarianism and parochialism have deep developmental roots, and the simultaneous emergence of altruistic sharing and parochialism during childhood is intriguing in view of recent evolutionary theories which predict that the same evolutionary process jointly drives both human altruism and parochialism.

/pdf/egalitarianism-in-young-children-4w2uvbcpcn.pdf

Egalitarianism in young children

Isolating a Culture of Son Preference Among Armenian, Georgian, and Azeri Parents in Soviet-Era Russia

Group Identities Make Fragile Tipping Points

Error management theory is a theory of considerable scope and emerging influence. The theory claims that cognitive biases do not necessarily reflect flaws in evolutionary design, but that they may be best conceived as design features. Unfortunately, existing accounts are vague with respect to the key concept of bias. The result is that it is unclear that the cognitive biases that the theory seeks to defend are not simply a form of behavioral bias, in which case the theory reduces to a version of expected utility theory. We propose some clarifications and refinements of error management theory by emphasizing important distinctions between different forms of behavioral and cognitive bias. We also highlight a key assumption, that the capacity for Bayesian beliefs is subject to constraints. This assumption is necessary for what we see as error management theory's genuinely novel claim: that behavioral tendencies to avoid costly errors can rest on systematic departures from Bayesian beliefs and that the latter can be adaptive insofar as they generate the former.

Short Communication The subtleties of error management

https://www.cesifo.org/DocDL/cesifo1_wp10133.pdf

Super-Additive Cooperation

The popular practice of “leading by the successful” is viewed as a hallmark of motivational leadership. A central rationale for leaders to make successful team members salient is that it may induce social learning, where followers strive to adopt a favorable behavior. The reliance of a leader on such success-biased social learning presumes that imitation by followers occurs only to the extent as outstanding success was caused by a superior ability or knowledge of the respective peer. In this article, we conduct a laboratory experiment to study whether imitation of the successful may occur even if imitation necessarily fails to be an effective way of improving one’s performance. The experimental approach establishes the necessary control to assure that success-biased learning cannot systematically improve the decisions made, and allows us to isolate the behavior of the followers from possible feedback effects of the leader. The data show that a substantial amount of imitation occurs, which in our setting leads to a sizeable and persistent increase of the average risk taken in the teams. Our finding thus indicates a limitation of the practice to lead with the successful.

https://www.zora.uzh.ch/id/eprint/202541/1/econwp382.pdf

Charles Efferson

Papers

Isolating a Culture of Son Preference Among Armenian, Georgian, and Azeri Parents in Soviet-Era Russia

Group Identities Make Fragile Tipping Points

Short Communication The subtleties of error management

Super-Additive Cooperation

Leading with the (recently) successful? Performance visibility and the evolution of risk taking