Amalgam and composite use in UK general practice in 2001

OBJECTIVE: This study determined the reasons for dentists' choice of materials, in particular amalgam and resin composite, in Great Britain. METHOD: A questionnaire was developed to elicit this information. The names and addresses of 1,000 UK-based dentists were selected at random. The questionnaire was mailed to these dentists with an explanatory letter and reply-paid envelope. RESULTS: Six hundred and fifty four replies were received. Regarding choice of material, 100% of respondents cited clinical indication as the most influential factor, although patients' aesthetic demands (99%), patients' choice (95%) and patients' financial situation (92%) were also reported to influence respondents' choice. Thirty-five per cent of respondents used composite 'sometimes', 15% 'often', and 1% 'always' in extensive load-bearing cavities in molar teeth. For composite restorations in posterior teeth, 92% 'always', 'often' or 'sometimes' used the total etch technique and 53% never used rubber dam. Seventy per cent of respondents agreed with the statement 'discontinuation of amalgam restricts a dentist's ability to adequately treat patients'. Eighty-one per cent considered that the growth in the use of composites increased the total cost of oral healthcare. CONCLUSIONS: Forty nine per cent of the respondents from England and Wales seldom or never place large composite restorations in molar teeth. Their choice of material is influenced greatly by clinical indications, and patients' aesthetic demands

The evolution of food sharing in primates

The aim of this study is to explain the occurrence of food sharing across primates. Defined as the unresisted transfer of food, evolutionary hypotheses have to explain why possessors should relinquish food rather than keep it. While sharing with offspring can be explained by kin selection, explanations for sharing among unrelated adults are more controversial. Here we test the hypothesis that sharing occurs with social partners that have leverage over food possessors due to the opportunity for partner choice in other contexts. Thus, we predict that possessors should relinquish food to potential mates or allies, who could provide or withhold matings or coalitionary support in the future. We used phylogenetic analyses based on both maximum likelihood and Bayesian approaches in a sample of 68 primate species to test these predictions. The analyses strongly indicate that (1) sharing with offspring is predicted by the relative processing difficulty of the diet, as measured by the degree of extractive foraging, but not overall diet quality, (2) food sharing among adults only evolved in species already sharing with offspring, regardless of diet, and (3) male–female sharing co-evolved with the opportunity for female mate choice and sharing within the sexes with coalition formation. These results provide comparative support for the hypothesis that sharing is “traded” for matings and coalitionary support in the sense that these services are statistically associated and can thus be selected for. Based on this, we predict that sharing should occur in any species with opportunities for partner choice

The reach of gene–culture coevolution in animals

Culture (behaviour based on socially transmitted information) is present in diverse animal species, yet how it interacts with genetic evolution remains largely unexplored. Here, we review the evidence for gene–culture coevolution in animals, especially birds, cetaceans and primates. We describe how culture can relax or intensify selection under different circumstances, create new selection pressures by changing ecology or behaviour, and favour adaptations, including in other species. Finally, we illustrate how, through culturally mediated migration and assortative mating, culture can shape population genetic structure and diversity. This evidence suggests strongly that animal culture plays an important evolutionary role, and we encourage explicit analyses of gene–culture coevolution in nature.Peer reviewe