The positive versus negative distinction of schizophrenic disorders has pro- moted ongoing research. Phenomenology, psychopathology, biology, genet- ics, pharmacological and nonpharmacological treatment, psychosocial and longitudinal research: all have found a new focus of interest. This volume attempts to provide an unbiased picture of the status of American and Eu- ropean knowledge regarding the positive/negative distinction. Researchers from North America and Europe describe the relation of modern concepts of positive and negative symptomatology to the original models of Rey- nolds and Jackson. Integrating phenomenological, genetic, and biological factors, the authors depict current methods of assessing positive and nega- tive symptomatology, differentiating between primary and secondary symp- tomatology, and using pharmacological and nonpharmacological treatment. The stability of positive and negative symptoms over time and evidence for the occurrence of separate positive and negative episodes over a long-term course of schizophrenia are extensively discussed in terms of their implica- tions on the positive/negative construct. The relevance of the positive/nega- tive dichotomy to child and adolescent schizophrenia is also debated. The main aim of this book is not to advocate a single concept and present only arguments supporting it, but to discuss important controversies. Prob- lems concerning a concept cannot be solved by ignoring them. However, unanswered questions may be resolved through discussion, debate, and con- structive compromise.

This is the first volume to address directly the question of the speciation of modern Homo sapiens. The subject raises profound questions about the nature of the species, our defining characteristic (it is suggested it is language), and the brain changes and their genetic basis that make us distinct. The British Academy and the Academy of Medical Sciences have brought together experts from palaeontology, archaeology, linguistics, psychology, genetics and evolutionary theory to present evidence and theories at the cutting edge of our understanding of these issues.
Palaeontological and genetic work suggests that the transition from a precursor hominid species to modern man took place between 100,000 and 150,000 years ago. Some contributors discuss what is most characteristic of the species, focussing on language and its possible basis in brain lateralization. This work is placed in the context of speciation theory, which has remained a subject of considerable debate since the evolutionary synthesis of Mendelian genetics and Darwinian theory. The timing of specific transitions in hominid evolution is discussed, as also is the question of the neural basis of language. Other contributors address the possible genetic nature of the transition, with reference to changes on the X and Y chromosomes that may account for sex differences in lateralization and verbal ability. These differences are discussed in terms of the theory of sexual selection, and with reference to the mechanisms of speciation.
These essays will be vital reading for anyone interested in the nature and origins of the species, and specifically human abilities.