When do anomalies begin?

An anomaly in science is an observed fact that is difficult to explain in terms of the existing conceptual framework. Anomalies often point to the inadequacy of the current theory and herald a new one. It is argued here that certain scientific anomalies are recognized as anomalies only after they are given compelling explanations within a new conceptual framework. Before this recognition, the peculiar facts are taken as givens or are ignored in the old framework. Such a "retrorecognition" phenomenon reveals not only a significant feature of the process of scientific discovery but also an important aspect of human psychology.     

ECOLOGY: When Do Many Species Matter?

Ecologists agree that experimental plots of grasses are sometimes more productive when they harbor more species. But some disagree passionately about whether it matters--in other words, whether this proves that biodiversity is critical to ecosystem health (see main text).     

When is an island community in equilibrium?

To determine whether the number of species in a biota is in equilibrium requires a colonization model. In a simple Markov model, each species' extinction and immigration probabilities are estimated independently from available data. For one inland and two island avifaunas, a simulation with these probabilities shows that the trajectories of species richness through time do not manifest the regulatory tendencies expected if species interactions cause species richness to be continuously redressed toward an equilibrium.