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We argue that Benenson et al. need to consider not only sex differences in the effects of care on offspring survival but also in age-specific fertility when predicting how longevity affects fitness. We review evidence that staying alive has important effects on both women's and men's fitness, and encourage consideration of alternative explanations for observed sex differences in threat responses.

The prevalence of type 2 diabetes (T2D) is low in populations with a high fish intake; however prospective studies with fish intake have shown positive, negative or no association between fish intake and the risk for T2D. The aim of this study was to investigate the effects of high intake of lean or fatty fish on glucose tolerance, leucocyte membrane fatty acid composition and leucocyte function in overweight/obese adults. In this randomised clinical trial, sixty-eight healthy overweight/obese participants consumed 750 g/week of either lean or fatty fish as dinners, or were instructed to continue their normal eating habits but to avoid fish intake (control group), for 8 weeks. Energy and macronutrient intake and physical activity were not changed within the groups during the study period. High intake of fatty fish, but not of lean fish, significantly improved glucose regulation 120 min postprandially (P=0·012), but did not affect fasting glucose concentration. A smaller increase in fasting to 120 min postprandial insulin C-peptide concentration was seen after fatty fish intake (P=0·012). Lean fish increased the DHA content in leucocyte membranes (P=0·010), and fatty fish increased the total content of n-3 PUFA (P=0·00016) and reduced the content of n-6 PUFA (P=0·00057) in leucocyte membranes. Lean and fatty fish intake did not affect phagocytosis of bacteria ex vivo. The findings suggest that high intake of fatty fish, but not of lean fish, beneficially affected postprandial glucose regulation in overweight/obese adults, and may therefore prevent or delay the development of T2D in this population.

The aim of the present study was to examine whether high intake of lean or fatty fish (cod and farmed salmon, respectively) by healthy, normal-weight adults would affect risk factors of type 2 diabetes and CVD when compared with lean meat (chicken). More knowledge is needed concerning the potential health effects of high fish intake (>300 g/week) in normal-weight adults. In this randomised clinical trial, thirty-eight young, healthy, normal-weight participants consumed 750 g/week of lean or fatty fish or lean meat (as control) for 4 weeks at dinner according to provided recipes to ensure similar ways of preparations and choices of side dishes between the groups. Energy and macronutrient intakes at baseline and end point were similar in all groups, and there were no changes in energy and macronutrient intakes within any of the groups during the course of the study. High intake of fatty fish, but not lean fish, significantly reduced TAG and increased HDL-cholesterol concentrations in fasting serum when compared with lean meat intake. When compared with lean fish intake, fatty fish intake increased serum HDL-cholesterol. No differences were observed between lean fish, fatty fish and lean meat groups regarding fasting and postprandial glucose regulation. These findings suggest that high intake of fatty fish, but not of lean fish, could beneficially affect serum concentrations of TAG and HDL-cholesterol, which are CVD risk factors, in healthy, normal-weight adults, when compared with high intake of lean meat.

The problem of the activity of extragalactic objects is one of the main problems of current astrophysics. There are many manifestations of activity but the photometric and polarimetric variability in IR, optical, UV and X-ray regions is probably one of the most important. The sources responsible for the variability are placed in the nearest neighbourhood of a central engine. Clarifying the nature of these sources might give a tool to the solution of the problem of nuclear activity in general.

The analysis of multicolor observations of BL Lac obtained in the 1997 and 1999 outbursts shows that in both cases the spectral energy distribution of the variable source was unchanged in the course of outburst. The sources have power-law spectra with slightly different spectral indices (the spectrum was flatter in the more powerful outburst of 1997). The variable source is most probably of synchrotron nature.