Abstract: Some researchers have proposed that natural selection has given rise in humans to one or more adaptations for altruistically punishing on behalf of other individuals who have been treated unfairly, even when the punisher has no chance of benefiting via reciprocity or benefits to kin. However, empirical support for the altruistic punishment hypothesis depends on results from experiments that are vulnerable to potentially important experimental artefacts. Here, we searched for evidence of altruistic punishment in an experiment that precluded these artefacts. In so doing, we found that victims of unfairness punished transgressors, whereas witnesses of unfairness did not. Furthermore, witnesses’ emotional reactions to unfairness were characterized by envy of the unfair individual's selfish gains rather than by moralistic anger towards the unfair behaviour. In a second experiment run independently in two separate samples, we found that previous evidence for altruistic punishment plausibly resulted from affective forecasting error—that is, limitations on humans’ abilities to accurately simulate how they would feel in hypothetical situations. Together, these findings suggest that the case for altruistic punishment in humans—a view that has gained increasing attention in the biological and social sciences—has been overstated.

Abstract: Social interactions facilitate animals learning of new features of their environment minimizing a trial and error process. It has been observed in some species that food cues can be acquired by one individual (the observer) from an animal model (demonstrator) due to social learning. Three experiments were performed to evaluate whether weaned piglets may show a preference for a flavoured feed following brief social interactions (30min) with an experienced demonstrator. After the social interaction between demonstrator and observer pigs, a 30-min choice test between the flavoured feed previously eaten by demonstrators (DEM-feed) and other flavoured feed (OTH-feed; Exp. 1 and 2) or a known unflavoured starter diet (Exp. 3) was performed with observer animals. Greater intake of DEM-feed occurred when demonstrators and observers were from the same pen (Exp. 1) or from the same litter (Exp. 2), but not when observers and demonstrators were unfamiliar with each other (Exp. 1). Observers also preferred flavours previously eaten by the demonstrator over their unflavoured diet already known. Social interactions with a conspecific pig that had a recent experience with a flavoured feed enhanced the preference for that feed and could even override neophobia to a new feed. The familiarity of conspecific demonstrators plays a key role in social learning of new feed cues probably due to selective exploration involving closer snout-to-snout contacts with kin conspecifics.

Abstract: In contrast to the great similarity in behaviour and ecology of the 6 extant Equid species, 2 distinct types of social organisation have evolved, and both are adapted to life in semi-arid to arid regions where environmental conditions force them to migrate seasonally or opportunistically.
The ranges of the various species overlap: Mountain Zebra Equus zebra and Plains Zebra E. quagga in South Africa and Namibia, Plains Zebra and Grevy's Zebra E. grevyi in Kenya and Ethiopia, Grevy's Zebra and African Wild Ass E. africanus in Ethiopia, Asiatic Wild Ass E. hemionus and Przewalski Horse E. przewalski in Mongolia and China. Although, in the overlap zones, individuals of the different species are using the same resources like water and grazing next to each other, they rarely make closer contacts.
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In the type 1 species, Horse, Plains Zebra and Mountain Zebra, the adults live in non-territorial, stable, one-male families and as single bachelors and in bachelor groups. Family stallions have the exclusive mating rights with the mares in their harems. These consist of up to 6 unrelated mares plus their offspring, totalling up to 20 members.
Mares stay in their harem until death. Stallions' tenure is from age 5-6 years, i.e. when they succeed in controlling a harem, for close to life time, but are replaced when dead or incapacitated. Harems are stable even in the absence of a stallion, indicating voluntary membership. Adolescent mares leave their parental families to become members of another harem.
In Plains Zebra the adolescent mares are abducted, during an oestrus, by suitors who fight the defending family stallion/father. Successful stallions are bachelors who start a family, or family stallions enlarging their harem. Young stallions leave their parental families voluntarily at age 2-3 years and join bachelor stallion groups from where the family stallions are recruited.
An individualised dominance hierarchy excists with the stallion in the alpha position. It is based on individual knowledge and recognition of the members.
In the type 2 species Grevy's Zebra, African Wild Ass and Asiatic Wild Ass adult stallions monopolise territories in which they have the exclusive mating rights. Stallions are tolerant of any conspecifics entering their territory. Bachelor stallions behave subordinately – or fight for the possession of the territory which is a prerequisite for reproduction.
Mares join up to form anonymous and unstable groups or herds. The only stable unit is of a mare and her offspring. In Grevy's Zebra mares with foal join preferentially conspecifics of the same soial status, as do mares without foal.
Matings take place inside the territory. There is no lasting relationship of the mare with a particular stallion, and the mare may be mated by any stallion whose territory she is visiting.
Territories measure up to 10 or more square kilometres, and tenure is for several years.
Grevy Zebra territorial owners leave their territories for a few hours to visit a water hole, or for months when grazing and water conditions are below requirements, and re-occupy it upon return, unchallenged.

Abstract: Removing a horse from its social group may be considered risky, both for the handler and the horse, because other horses can interfere in the catching process. The main aim of this study was to identify where and when these risk situations occur while removing a horse from its group. A potential risk situation was defined by the closeness of loose horses in the group or by any physical contact with them. Whether the number of horses following would be influenced by the social rank of the horse being led out, and whether more horses would follow to the gate when a larger proportion of the group was removed compared to when a single horse was taken out were also investigated. Thirty-two mares (1–2 years) were kept in groups of four. All horses were taken out of their home paddock twice alone (64 tests) and twice with a companion (32 tests). One handler (or two handlers when two horses were removed) was asked to approach (phase 1) and catch the target horse (phase 2), walk it to the centre of the paddock and remain stationary at a post for 30 s (phase 3), walk to the paddock entrance (phase 4) and through the gate (phase 5). The number of horses following, and the number of loose horses in proximity (<2 m, 2–5 m) to the target horse and handler was estimated, and horse–horse and horse–human interactions were recorded continuously for the five scoring phases. Significantly more loose horses were within 2 m of a single target horse during the phases approach (mean ± SD: 1.5 ± 0.8), catch (1.6 ± 0.9) and post (1.7 ± 0.7) than during walk (1.0 ± 0.5) and gate (1.1 ± 0.6). Rank did not influence the number of horses following to the gate (high rank: 2.4 ± 0.7; lower rank: 2.0 ± 1.0; P = 0.396) and interactions between horses were rare. A greater proportion of the loose horses followed when two horses (0.9 ± 0.2) were removed compared to when a single horse (0.7 ± 0.3) was taken out (P = 0.011). In conclusion, maintaining a distance to other horses in the group by reducing the time being relatively stationary, so giving loose horses fewer chances to approach, is likely to contribute to improved handler's safety. Removing a small proportion of the group may also decrease the probability of the other horses following.