The reality of the higher taxonomic categories

A higher category is the result of a population's breaking-throuh into a new adaptive zone (attaining a new grade), and the subsequent adaptive radiation tiere. The taxonomic level of the new group is determined by the amount (quantitative and ualitative) of radiation that occurs; and tgis amount in turn is determined by the number of open sub-zones in the new zone and by the genetic plasticity of the new population. The more the new adaptive zone differs from the old one, the less likely a new population can survive in it. Should such survival occur, however, adaptations of the new population to the new zone will appear quickly. The new population will rapidly become quite different from the old one, minimizing the likelihood of finding intermediate forms, i. e., “missing links.” In addition, the intermediate population – the early entrants into the new zone – will be less well adapted to it than their descendents, and will become extinct. The combination of rapid extinction and an ephemeral transitional population explains the apparent gaps between higher-category taxa. These ideas do not help in solving such dilemmas of taxonomists as equivalence of taxa in different groups, and the taxonomic level at which to place a given group of species. But a higher taxonomic category itself is the result of a very real biological phenomenon, and that fact must influence systematicists.     

Change across the lifespan in a psychological measure of life history strategy

Life history theory predicts that people calibrate their reproductive strategies to local levels of environmental harshness and unpredictability. While previous research has established the importance of early life cues in the development of life history strategy, the degree to which life history strategy exhibits plasticity later in life is unclear. Using longitudinal data (total N = 479) from four archival studies and a recently validated psychological measure of life history strategy, we examined mean-level trends in life history strategy at the level of psychological phenotype between the ages of 7 and 60 and found that life history strategy slowed down linearly as a function of age. Highlighting the importance of sexual selection in shaping life history strategy, we also found that men had a faster life history strategy than women at all ages and that the magnitude of this difference was constant across the lifespan. Our findings suggest that life history strategy development continues even in older adulthood. We discuss the possibility that this occurs in response to the accumulation of biological and social (e.g. offspring, relationships) capital and information about local risks and incentives.     

The construction of ethnic categories: Discourses of ethnicity in The Netherlands

This article is concerned with the way ethnic and racial categories are achieved and sustained in daily talk. We argue against the notion of social categories as immanent cognitive structures whose existence and significance can be taken for granted. It is emphasized that categories are constructed in discourse. The construction and representation of ethnic categories are studied by analysing discussions held by some ethnically Dutch inhabitants of an inner‐city quarter in Rotterdam. There were two discussion groups (six and five participants respectively) and each group met one evening a week in a row in the local community centre for four weeks. All eight sessions were taped and transcribed and each session lasted approximately two and a half hours. Our goal is to describe in detail some of the discourses that are being used to achieve and sustain specific categorical representations. First, the nature of the different categorical constructs used is analysed. It is shown that people use different criteria for constructing ‘us‐them’ distinctions and that this multiplicity is rhetorically useful. Second, the ways in which categorical constructions are represented and vary in discourse are identified and outlined. Subsequently, the means by which these representations are achieved and sustained is examined. Attention is focued on comparisons that are being made, on the use of metaphors, and on the process of concretiz‐ation. Third, some of the cultural values drawn upon in legitimizing the representations are explored. It is shown how the taken‐for‐granted notions of freedom, merit, equality and tolerance are used to construct and legitimize ethnic representations. Finally, it is argued that a discourse approach can provide important additional insights into issues concerning ethnic relations and racism. For one thing it can help to develop strategies for reconstructing the predominant distinction between ‘us’ and ‘them’.     

The prefrontal cortex: categories,concepts and cognition

The ability to generalize behaviour-guiding principles and concepts from experience is key to intelligent, goal-directed behaviour. It allows us to deal efficiently with a complex world and to adapt readily to novel situations. We review evidence that the prefrontal cortex-the cortical area that reaches its greatest elaboration in primates-plays a central part in acquiring and representing this information. The prefrontal cortex receives highly processed information from all major forebrain systems, and neurophysiological studies suggest that it synthesizes this into representations of learned task contingencies, concepts and task rules. In short, the prefrontal cortex seems to underlie our internal representations of the 'rules of the game'. This may provide the necessary foundation for the complex behaviour of primates, in whom this structure is most elaborate.     

Infraspecific categories in fungi

The problems facing the mycologist centre on the difficulty of distinguishing between the individual and the population, the degree of host or substratum specialization and the limited range of morphological characters available for use as denning taxa. The use of the categories 'variety' and 'forma specialis' is considered, and examples are given of their application in the cereal rusts and in the genera Phoma and Fusarium. Micro-evolutionary trends in Auricula auricula are also considered and are used to illustrate how amenable fungi are to studies on speciation.