Wild redfronted lemurs (Eulemur rufifrons) use social information to learn new foraging techniques

Recent research has claimed that traditions are not a unique feature of human culture, but that they can be found in animal societies as well. However, the origins of traditions in animals studied in the wild are still poorly understood. To contribute comparative data to begin filling this gap, we conducted a social diffusion experiment with four groups of wild redfronted lemurs (Eulemur rufifrons). We used a ‘two-option’ feeding box, where these Malagasy primates could either pull or push a door to get access to a fruit reward to study whether and how these two behavioural traits spread through the groups. During a pre-training phase, two groups were presented with boxes in which one technique was blocked, whereas two groups were presented with unblocked boxes. During a subsequent unconstrained phase, all four groups were confronted with unblocked boxes. Nearly half of the study animals were able to learn the new feeding skill and individuals who observed others needed fewer unsuccessful task manipulations until their first successful action. Animals in the two groups with pre-training also discovered the corresponding alternative technique but preferred the seeded technique. Interestingly, animals in the two groups without pre-training discovered both techniques, and one group developed a group preference for one technique whereas the other did not. In all groups, some animals also scrounged food rewards. In conclusion, redfronted lemurs appear to use social information in acquiring a novel task, and animals in at least in one group without training developed a group preference for one technique, indicating that they have the potential to develop behavioural traditions and conformity

Body-form Evolution in the Scincid Lizard Clade Lerista and the Mode of Macroevolutionary Transitions

© Springer Science+Business Media, LLC 2009The scincid lizard clade Lerista provides an exceptional model for studying the mode of substantial evolutionary transformations, comprising more than 90 species displaying a remarkable variety of body forms. Patterns of character evolution in this clade, inferred from reconstructed ancestral states, are at least partly consistent with the correlated progression model of macroevolutionary change. At each stage in the transition to a highly elongate, limb-reduced body plan, alterations to the lengths of the forelimb and hind limb are accompanied by compensatory changes in snout-vent length (or vice versa), preserving locomotory ability. Nonetheless, there is evidence for moderate dissociation of hind limb evolution in some lineages, while tail length has evolved effectively independently of the substantial alterations to the lengths of the body and limbs. This indicates a significant role of evolutionary and developmental modularity in the divergence of body form within Lerista, and emphasises the potential variability of the strength of functional constraints within organisms and among lineages. Trends toward a highly elongate, functionally limbless body plan may be attributed primarily to a combination of the interdependence of changes in snout-vent length and limb lengths and the very low probability of re-elaborating structurally reduced limbs. Similar asymmetries in the probabilities of interrelated phenotypic changes may be a significant cause of evolutionary trends resulting in the emergence of higher taxa.Adam Skinner and Michael S. Y. Le

Cognitive consequences of cooperative breeding in primates?

Several hypotheses propose that cooperative breeding leads to increased cognitive performance, in both nonhuman and human primates, but systematic evidence for such a relationship is missing. A causal link might exist because motivational and cognitive processes necessary for the execution and coordination of helping behaviors could also favor cognitive performance in contexts not directly related to caregiving. In callitrichids, which among primates rely most strongly on cooperative breeding, these motivational and cognitive processes include attentional biases toward monitoring others, the ability to coordinate actions spatially and temporally, increased social tolerance, increased responsiveness to others’ signals, and spontaneous prosociality. These processes are likely to enhance performance particularly in socio-cognitive contexts. Therefore, cooperatively breeding primates are expected to outperform their independently breeding sister taxa in socio-cognitive tasks. We evaluate this prediction by reviewing the literature and comparing cognitive performance in callitrichids with that of their sister taxa, i.e. squirrel monkeys, which are independent breeders, and capuchin monkeys, which show an intermediate breeding system. Consistent with our prediction, this review reveals that callitrichids systematically and signiWcantly outperform their sister taxa in the socio-cognitive, but not in the non-social domain. This comparison is complemented with more qualitative evaluations of prosociality and cognitive performance in non-primate cooperative breeders, which suggest that among mammals, cooperative breeding generally produces conditions conducive to socio-cognitive performance. In the hominid lineage, however, the adoption of extensive allomaternal care presumably resulted in more pervasive cognitive consequences, because the motivational consequences of cooperative breeding was added to an ape-level cognitive system already capable of understanding simple mental states, which enabled the emergence of shared intentionality