The evolution of cooperation is a fundamental problem in biology, especially for non-relatives, where indirect fitness benefits cannot counter within-group inequalities. Multilevel selection models show how cooperation can evolve if it generates a group-level advantage, even when cooperators are disadvantaged within their group. This allows the possibility of group selection, but few examples h...

BACKGROUND In many countries, there is a surplus of physicians in some communities and a shortage in others. Population size is known to be correlated with the number of physicians in a community, and is conventionally considered to represent the power of communities to attract physicians. However, associations between other demographic/economic variables and the number of physicians in a commu...

In the interest of conservation, the importance of having a large habitat available for a species is widely known. Here, we introduce a lattice-based model for a population and look at the importance of fluctuations as well as that of the population density, particularly with respect to Allee effects. We examine the model analytically and by Monte Carlo simulations and find that, while the size...

Space competition effects are well-known in many microbiological and ecological systems. Here we analyze such an effect in human populations. The Neolithic transition (change from foraging to farming) was mainly the outcome of a demographic process that spread gradually throughout Europe from the Near East. In Northern Europe, archaeological data show a slowdown on the Neolithic rate of spread ...

The data in this letter provide some insights into the complex needs of older adult psychiatric patients. If this sample is representative of a typical older adult population, then other services providing psychiatric care for older adults with similarly high levels of aggressive and challenging behavior may consider adopting a similar model in the safe practice of physical interventions. As th...

Explanations for rapid species' range expansions have typically been purely ecological, with little attention given to evolutionary processes. We tested predictions for the evolution of dispersal during range expansion using four species of wing-dimorphic bush cricket (Conocephalus discolor, Conocephalus dorsalis, Metrioptera roeselii, and Metrioptera brachyptera). We observed distinct changes ...

An important question in ecology is how mechanistic processes occurring among individuals drive large-scale patterns of community formation and change. Here we show that in two species of bluebirds, cycles of replacement of one by the other emerge as an indirect consequence of maternal influence on offspring behavior in response to local resource availability. Sampling across broad temporal and...

Culture is an important factor affecting happiness. This paper examines the predictive power of cultural factors on the cross-country differences in happiness and explores how different dimensions of cultural indices differ in their effects on happiness. Our empirical results show that the global leadership and organizational behavior effectiveness nine culture indices are all significantly rel...

We investigated the response of caddisfly species assemblages in the middle reaches of the Shinano River to a flood that occurred in mid July 2006. Prior to the flood (on Day -22) the population density of total benthic caddisflies was 8,266.7 ± 2,392.1 individuals m. After the flood, by Day 11, the population density had decreased to 55.6 ± 55.6 individuals m. By Day 65, the density of caddis ...

Most people on the planet live in dense aggregations, and policy directives emphasize green areas within cities to ameliorate some of the problems of urban living. Benefits of urban green spaces range from physical and psychological health to social cohesion, ecosystem service provision and biodiversity conservation. Green space coverage differs enormously among cities, yet little is known abou...