Abstract: Thin-layer chromatography, acetylation of reference and unidentified glucocorticosteroids, u.v. absorption and fluorescence induced in sulphuric acid were used to identify cortisol as the major free plasma glucocorticosteroid in the horse (Equus caballus), with cortisone and corticosterone as minor glucocorticosteroids. Deoxycorticosterone was also identified. The plasma ratio for free cortisol: cortisone: corticosterone was 16:8:0·5.The diurnal variation was determined for all three glucocorticosteroids. The highest levels of cortisol and corticosterone were found at 10.00 hr. (260 and 10·3 μg./100 ml., respectively) and the lowest concentration of cortisol at 02.00 hr. The highest level of cortisone occurred at 02.00 hr. (140 μg./100 ml.), and the lowest appeared at 16.00 hr. (65 μg./100 ml.). The maximum plasma concentration of the combined glucocorticosteroids was found at 10.00 hr. (395·3 μg./100 ml.), and the minimum at 20.00 hr. (219 μg./100 ml.).

Abstract: Summary One hundred and forty-four naive virgin female golden hamsters were each given a single 15 min test with three pups aged from day 1 (<24 hr) to day 18. A group of eight females was tested with each age of pup. Pups aged from day 1 to day 6 were generally attacked like prey, killed and eaten. Pups of intermediate age (day 6 to day 10) were usually initially attacked but this was often followed by maternal responses. The females', behaviour with the oldest pups suggested that they were being treated as strnge adult intruders. This result differs from that of a similar experiment with mice in which the youngest pups were found to be the most effective for eliciting materal responses. An explanation for this difference in terms of the evolutionary history of the golden hamster species is proposed.

Abstract: Summary Three groups of eight female golden hamsters without prior breeding experience were presented with three newborn pups for a 15 min test period. Group V were virgin females, group P pregnant females and group L lactating females. Groups P and L were tested within 24 hr of parturition. Group V attacked and killed all pups presented. Group P showed maternal responses after initial attacks while group L accepted the pups. Groups P and L did not differ significantly on measures of maternal responsiveness but all three groups differed significantly from one another on measures of attacking behaviour and the eating of young.

Abstract: Our human intellect has resulted from an enormous leap in capacity above the level of monkeys and apes. Earlier, though, Old and New World monkeys' intelligence outdistanced that of other mammals, including the prosimian primates. This first great advance in intelligence probably was selected through interspecific competition on the large continents. However, even at this early stage, primate social life provided the evolutionary context of primate intelligence.
Two arguments support this conclusion. One is ontogenetic: modern monkeys learn so much of their social behavior, and learn their behavior toward food and toward other species through social example. The second is phylogenetic: some prosimians, the social lemurs, have evolved the usual primate type of society and social learning without the capacity to manipulate objects as monkeys do. It thus seems likely that the rudiments of primate society preceded the growth of primate intelligence, made it possible, and determined its nature.