Abstract: The variability of most environments taxes foraging decisions by increasing the uncertainty of the information available. One solution to the problem is to use dynamic averaging, as do some granivores and carnivores. Arguably, the same strategy could be useful for grazing herbivores, even though their food renews and is more homogeneously distributed. Horses (Equus callabus) were given choices between variable patches after short or long delays. When patch information was current, horses returned to the patch that was recently best, whereas those without current information matched choices to the long-term average values of the patches. These results demonstrate that a grazing species uses dynamic averaging and indicate that, like granivores and carnivores, they can use temporal weighting to optimize foraging decisions.

Abstract: Two chimpanzees and a rhesus macaque rapidly learned the ordinal relations between 5 colors of containers (plastic eggs) when all containers of a given color contained a specific number of identical food items. All 3 animals also performed at high levels when comparing sets of containers with sets of visible food items. This indicates that the animals learned the approximate quantity of food items in containers of a given color. However, all animals failed in a summation task, in which a single container was compared with a set of 2 containers of a lesser individual quantity but a greater combined quantity. This difficulty was not overcome by sequential presentation of containers into opaque receptacles, but performance improved if the quantitative difference between sizes was very large.

Abstract: We studied experimentally whether horse dams influenced foals' relationships with humans. We investigated the influence of the establishment of positive human-mare relationships on foals' behaviour toward humans. Forty-one foals and their dams were involved in this experiment. Half of the mares were softly brushed and fed by hand during a short period (total of 1.25 h) during the first 5 days of their foals' lives (experimental group, n = 21). The other mares were not handled experimentally and their foals received no contact with the experimenter (control group, n = 20). The reactions of both experimental and control foals were recorded under various conditions, first, for 5 min in the presence of a motionless experimenter, when foals were 15 and 30-35 days old, then in an approach test when they were 15 days old and in a saddle-pad tolerance test when they were 30-35 days old. Finally, approach-stroking tests were performed successively by the familiar experimenter when foals were 11-13 months old and by an unfamiliar person when they were 13-15 months old. Several observations strongly suggest that mares can influence their foals' behaviour toward humans: (1) during the handling procedure, experimental foals of protective mares were further from the handler than foals of calm mares (p < 0.001); (2) experimental foals remained, at all ages, closer to the experimenter (p < 0.05) and initiated more physical contacts (sniffing, licking, etc.) with the experimenter (p < 0.05) than control foals; (3) avoidance and flight responses of experimental foals were considerably reduced during approaches by the experimenter (p < 0.01) and they accepted saddle-pads on their backs more easily (p < 0.01) and more quickly (p < 0.01) than control foals. Lastly, the consequences of handling mares had effects that lasted at least until foals were one year old (p < 0.05) and became generalized from experimenter to unfamiliar humans, who could approach and stroke experimental foals rapidly during a test (p < 0.05). This is the first report of an attempt to use observation of mother by foals to facilitate human-foal relationships. The procedure is simple, takes little time and can easily be applied to any dam-foal pair, as it is not intrusive and presents no risks of disrupting mare-foal bonds.

Abstract: We investigated lateralisation in horses because it is likely to be important in training and athletic performance. Thoroughbred horses (n = 106) were observed every 60 s for 2 h, when they were at pasture, and the position of the forelimbs in relation to one another was recorded. There was a population bias skewed to standing with the left forelimb advanced over the right (i.e. directional lateralisation). Using the first 50 observations, the distribution of preferences was 43 significantly left, 10 significantly right with 53 being non-significant (i.e. ambidextextrous). The strength of motor bias increased with age, suggesting maturation or an influence of training. The horses were also presented with an olfactory stimulus (stallion faeces) to score the tendency to use one nostril rather than the other. A significant preference to use the right nostril first was shown in horses under 4 years of age (n = 61) but not in older horses. Of the 157 horses tested for nostril bias, 76 had been assessed for motor bias and so were used for analysis of the relationship between laterality in the two modalities. There was no significant relationship between direction of foreleg motor bias and first nostril used, total number of inhalations or laterality index of nostril use. The absence of a correlation between laterality of nostril use and motor bias indicates that lateralisation of the equine brain occurs on at least two levels of neural organisation--sensory and motor--a finding that is consistent with other examples of lateralisation in species that have been examined in more detail.

Abstract: The ability to rehearse possible future courses of action in the mind is an important feature of advanced social cognition in humans, and the “social brain” hypothesis implies that it might also be a feature of primate social cognition. We tested two chimpanzees, six orangutans and 63 children aged 3-7 years on a set of four puzzle boxes, half of which were presented with an opportunity to observe the box before being allowed to open it (“prior view”), the others being given without an opportunity to examine the boxes before handling them (“no prior view”). When learning effects are partialled out, puzzle boxes in the “prior view” condition were opened significantly faster than boxes given in the “no prior view” condition by the children, but not by either of the great apes. The three species differ significantly in the speed with which they opened boxes in the “no prior view” condition. The three species' performance on this task was a function of relative frontal lobe volume, suggesting that it may be possible to identify quantitative neuropsychological differences between species.