Alcohol unleashes homo economicus by inhibiting cooperation.

Human behavior lies somewhere between purely self-interested homo economicus and socially-motivated homo reciprocans. The factors that cause people to choose self-interest over costly cooperation can provide insights into human nature and are essential when designing institutions and policies that are meant to influence behavior. Alcohol consumption can shed light on the inflection point between selfish and selfless because it is commonly consumed and has global effects on the brain. The present study administered alcohol or placebo (N = 128), titrated to sex and weight, to examine its effect on cooperation in a standard task in experimental economics, the public goods game (PGG). Alcohol, compared to placebo, doubled the number of free-riders who contributed nothing to the public good and reduced average PGG contributions by 32% (p = .005). This generated 64% higher average profits in the PGG for those who consumed alcohol. The degree of intoxication, measured by blood alcohol concentration, linearly reduced PGG contributions (r = -0.18, p = .05). The reduction in cooperation was traced to a deterioration in mood and an increase in physiologic stress as measured by adrenocorticotropic hormone. Our findings indicate that moderate alcohol consumption inhibits the motivation to cooperate and that homo economicus is stressed and unhappy.

Inferences of environmental and biotic effects on patterns of eukaryotic alpha and beta diversity for the spring systems of Ash Meadows, Nevada.

Freshwater springs are important ecosystems. In the arid regions of North America, groundwater extraction has caused the desiccation of springs and the extinction of taxa. To better describe the biodiversity of freshwater springs in the hope of establishing a sensitive approach for monitoring the predicted change in spring systems, we used high-resolution genetic methods to estimate the alpha and beta diversity of 19 springs and two reservoirs within the Ash Meadows National Wildlife Refuge in southwestern Nevada. We discovered a large number of distinct taxa based on eukaryote ribosomal gene sequences and show water temperature, spring size, and the presence or absence of non-native predators predicts alpha diversity, and temperature predicts beta diversity. Our study highlights how DNA data support inferences of environmental factors influencing community diversity and demonstrates the method may be an important tool for monitoring ecological communities.