Abstract: Some aspects of lateralization are widespread. This is clear for the association between left-eye (LE) use and readiness to respond intensely to releasing stimuli presented by others, which has been found in representatives of all major groups of tetrapods and in fishes. In the chick, this behavioural asymmetry is linked developmentally to greater ability to sustain response against distracting stimuli with right-eye (RE) use, in that both reverse with the reversal of the normal RE exposure to light. In the zebrafish, the same two asymmetries (normally) have similar associations with the LE and the RE, and both also reverse together (owing to epithalamic reversal). Here, we show that light exposure early in development is needed in zebrafish to generate both asymmetries. Dark development largely abolishes both the enhanced abilities, confirming their linkage. Resemblance to the chick is increased by the survival in the chick, after dark development, of higher ability to assess familiarity of complex stimuli when using the LE. A somewhat similar ability survives in dark-developed zebrafish. Here, LE use causes lesser reliance on a single recent experience than on longer term past experience in the assessment of novelty. Such resemblances between a fish and a bird suggest that we should look not only for resemblances between different groups of vertebrates in the most common overall pattern of lateralization, but also for possible resemblances in the nature of inter-individual variation and in the way in which it is generated during development.

Abstract: Indirect reciprocity1, 2, 3, 4, 5 is a key mechanism for the evolution of human cooperation. Our behaviour towards other people depends not only on what they have done to us but also on what they have done to others. Indirect reciprocity works through reputation5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17. The standard model of indirect reciprocity offers a binary choice: people can either cooperate or defect. Cooperation implies a cost for the donor and a benefit for the recipient. Defection has no cost and yields no benefit. Currently there is considerable interest in studying the effect of costly (or altruistic) punishment on human behaviour18, 19, 20, 21, 22, 23, 24, 25. Punishment implies a cost for the punished person. Costly punishment means that the punisher also pays a cost. It has been suggested that costly punishment between individuals can promote cooperation. Here we study the role of costly punishment in an explicit model of indirect reciprocity. We analyse all social norms, which depend on the action of the donor and the reputation of the recipient. We allow errors in assigning reputation and study gossip as a mechanism for establishing coherence. We characterize all strategies that allow the evolutionary stability of cooperation. Some of those strategies use costly punishment; others do not. We find that punishment strategies typically reduce the average payoff of the population. Consequently, there is only a small parameter region where costly punishment leads to an efficient equilibrium. In most cases the population does better by not using costly punishment. The efficient strategy for indirect reciprocity is to withhold help for defectors rather than punishing them.

Abstract: Explanations of cooperation between non-kin in animal societies often suggest that individuals exchange resources or services and that cooperation is maintained by reciprocity. But do cooperative interactions between unrelated individuals in non-human animals really resemble exchanges or are they a consequence of simpler mechanisms? Firm evidence of reciprocity in animal societies is rare and many examples of cooperation between non-kin probably represent cases of intra-specific mutualism or manipulation.

Abstract: Despite their ability to interbreed and produce fertile offspring, there is continued disagreement about the genetic relationship of the domestic horse (Equus caballus) to its endangered wild relative, Przewalski's horse (Equus przewalskii). Analyses have differed as to whether or not Przewalski's horse is placed phylogenetically as a separate sister group to domestic horses. Because Przewalski's horse and domestic horse are so closely related, genetic data can also be used to infer domestication-specific differences between the two. To investigate the genetic relationship of Przewalski's horse to the domestic horse and to address whether evolution of the domestic horse is driven by males or females, five homologous introns (a total of [~]3 kb) were sequenced on the X and Y chromosomes in two Przewalski's horses and three breeds of domestic horses: Arabian horse, Mongolian domestic horse, and Dartmoor pony. Five autosomal introns (a total of [~]6 kb) were sequenced for these horses as well. The sequences of sex chromosomal and autosomal introns were used to determine nucleotide diversity and the forces driving evolution in these species. As a result, X chromosomal and autosomal data do not place Przewalski's horses in a separate clade within phylogenetic trees for horses, suggesting a close relationship between domestic and Przewalski's horses. It was also found that there was a lack of nucleotide diversity on the Y chromosome and higher nucleotide diversity than expected on the X chromosome in domestic horses as compared with the Y chromosome and autosomes. This supports the hypothesis that very few male horses along with numerous female horses founded the various domestic horse breeds. Patterns of nucleotide diversity among different types of chromosomes were distinct for Przewalski's in contrast to domestic horses, supporting unique evolutionary histories of the two species.

Abstract: We investigated whether cattle exhibit preferences to monitor challenging and novel stimuli. Experiments were conducted on dairy and beef cattle herds and revealed significant left eye preferences in the cattle for viewing an experimenter walking to repeatedly split the herd through its centre. Visual lateralisation was demonstrated in the preference to use the left monocular field to monitor the experimenter, alone or equipped with a range of novel stimuli. This finding is consistent with left eye preferences found in various species of mammals, birds, and amphibians responding to predators and novel stimuli. A cohort of the familiarised cattle herds was then subjected to additional herd-splitting tests with the same stimuli and demonstrated a reversal of viewing preferences, preferring to monitor the experimenter and stimuli within the right and not left monocular field. This directional shift in viewing preferences is consistent with experience-dependent learning found in lateralised visual processing in other, non-mammalian, species, and to our knowledge is the first of such studies to suggest that such lateralised learning processes also exist in mammals. Together the data support a number of key hypotheses concerning the evolution and conservation of lateralised brain function in vertebrates, and also provide important considerations for livestock handling.