When social psychology became less social: Prasad and the history of rumor research

Rumor research, in general, and its delayed incorporation of the work, of rumor researcher Jamuna Prasad, in particular, exemplify how the intellectual climate of American social psychology discouraged the development of social approaches. In the present paper, we explain his conceptualization of how rumors start and spread, and explore findings from subsequent research supporting or negating his propositions. It is our contention that, although Prasad had identified the basic variables involved in rumor generation and transmission correctly, mainstream social psychological research in the 1940s did not incorporate his contributions. Instead, mirroring the Zeitgeist of American social psychology, rumor research was approached from a predominantly individual level of analysis. In the present paper, the authors have tried to resurrect some of the group-level variables from Prasad's treatment of rumor and to suggest that social psychology adopt a more 'social' approach to rumor.

Geographic range size, life history and rates of diversification in Australian mammals

What causes species richness to vary among different groups of organisms? Two hypotheses are that large geographical ranges and fast life history either reduce extinction rates or raise speciation rates, elevating a clade's rate of diversification. Here we present a comparative analysis of these hypotheses using data on the phylogenetic relationships, geographical ranges and life history of the terrestrial mammal fauna of Australia. By comparing species richness patterns to null models, we show that species are distributed nonrandomly among genera. Using sister-clade comparisons to control for clade age, we then find that faster diversification is significantly associated with larger geographical ranges and larger litters, but there is no evidence for an effect of body size or age at first breeding on diversification rates. We believe the most likely explanation for these patterns is that larger litters and geographical ranges increase diversification rates because they buffer species from extinction. We also discuss the possibility that positive effects of litter size and range size on diversification rates result from elevated speciation rates.

Late Devonian acanthodians from Colombia

Acanthodian remains occur in micaceous siltstone lenses (presumed to have been deposited during a marine incursion) in the Cuche Formation (?Frasnian) of northeast Colombia. The acanthodians are represented by patches of scales from climatiidid Nostolepis sp. cf. N. gatijensis and a fin spine and scales from a new diplacanthid. Type material of N. gaujensis is from the Frasnian Sventoji regional stage in the Baltic, and Nostolepis sp. cf. N. gaujensis has been recorded in the Frasnian of Iran, as well as from Colombia. The new diplacanthid taxon shows affinity to Baltic and Antarctic diplacanthids. The fauna thus shows possible links to both Gondwanan and Euramerican acanthodian assemblages. (C) 2003 Elsevier Science Ltd. All rights reserved.