Conformity in mate choice, the overlooked social component of animal and human culture.

Although conformity as a major driver for human cultural evolution is a well-accepted and intensely studied phenomenon, its importance for non-human animal culture has been largely overlooked until recently. This limited for decades the possibility of studying the roots of human culture. Here, we provide a historical review of the study of conformity in both humans and non-human animals.

Evaluating social contract theory in the light of evolutionary social science.

Political philosophers have long drawn explicitly or implicitly on claims about the ways in which human behaviour is shaped by interactions within society. These claims have usually been based on introspection, anecdotes or casual empiricism, but recent empirical research has informed a number of early views about human nature. We focus here on five components of such views: (1) what motivates human beings; (2) what constraints our natural and social environments impose upon us; (3) what kind of society emerges as a result; (4) what constitutes a fulfilling life; and (5) what collective solutions can improve the outcome.

Many causes, not one.

This comment focuses on difficulties in establishing causality among various phenomena present in early modern Europe at the beginning of the Industrial Revolution. It concludes that, rather than focus on a single cause out of many candidates, we should consider the possibility of a set of mutually reinforcing causes, among which those suggested by Life History Theory may be included.

Parent-offspring conflict over mate choice: An experimental study in China.

Both parents and offspring have evolved mating preferences that enable them to select mates and children-in-law to maximize their inclusive fitness. The theory of parent-offspring conflict predicts that preferences for potential mates may differ between parents and offspring: individuals are expected to value biological quality more in their own mates than in their offspring's mates and to value investment potential more in their offspring's mates than in their own mates. We tested this hypothesis in China using a naturalistic 'marriage market' where parents actively search for marital partners for their offspring.

The role of insulin dissociation from its endosomal receptor in insulin degradation.

Mechanisms that terminate signals from activated receptors have potential to influence the magnitude and nature of cellular responses to insulin. The aims of this study were to determine in rat liver endosomes (the subcellular site of insulin signal termination) whether dissociation of insulin from its receptor was a pre-requisite for ligand degradation and whether the state of receptor phosphorylation influenced the dissociation and hence endosomal degradation of insulin and/or receptor recycling. Following in vivo administration of 125I-[A14]-insulin or analogues (native, X10 or H2, relative binding affinities 1:7:67) livers were removed and endosomes prepared.

Chloroquine extends the lifetime of the activated insulin receptor complex in endosomes.

Insulin signal transduction, initiated by binding of insulin to its receptor at the plasma membrane, activates the intrinsic receptor tyrosine kinase and leads to internalization of the activated ligand-receptor complex into endosomes. This study addresses the role played by the activated insulin receptor within hepatic endosomes and provides evidence for its central role in insulin-stimulated events in vivo. Rats were treated with chloroquine, an acidotrophic agent that has been shown previously to inhibit endosomal insulin degradation, and then with insulin.

The characterization of endosomal insulin degradation intermediates and their sequence of production.

Insulin degradation within isolated rat liver endosomes was studied in vitro with the aid of three 125I-insulin isomers specifically labelled at tyrosine (A14, B16 and B26). Chloroquine and 1,10-phenanthroline were used to minimize insulin proteolysis during endosome preparation, whereas the manipulation of endosomal processing of insulin in vitro by Co2+ ions (to activate) and 1,10-phenanthroline (to inhibit) permitted the study of degradation intermediates and their time-dependent production. Structural and kinetic analysis of intermediates isolated from both intra- and extra-endosomal compartments allowed the determination of major cleavage sites and the probable sequence of proteolytic events.

Uptake of aluminium by human neuroblastoma cells.

We have treated human neuroblastoma cells with various complexes of aluminium, over a range of concentrations, and have measured the amount of aluminium entering the cells after one week, using atomic absorption spectroscopy. We have found that the cells incorporate much higher levels of the element after treatment with aluminium-EDTA than with aluminium-citrate or aluminium-maltol. With aluminium-EDTA, initially the uptake increases with increasing concentration in the medium but eventually reaches a plateau; the concentration within the cells is then higher than that in the medium.