Specialization in the vicarious learning of novel arbitrary sequences in humans but not orangutans.

Sequence learning underlies many uniquely human behaviours, from complex tool use to language and ritual. To understand whether this fundamental cognitive feature is uniquely derived in humans requires a comparative approach. We propose that the vicarious (but not individual) learning of novel arbitrary sequences represents a human cognitive specialization. To test this hypothesis, we compared the abilities of human children aged 3-5 years and orangutans to learn different types of arbitrary sequences (item-based and spatial-based). Sequences could be learned individually (by trial and error) or vicariously from a human (social) demonstrator or a computer (ghost control). We found that both children and orangutans recalled both types of sequence following trial-and-error learning; older children also learned both types of sequence following social and ghost demonstrations. Orangutans' success individually learning arbitrary sequences shows that their failure to do so in some vicarious learning conditions is not owing to general representational problems. These results provide new insights into some of the most persistent discontinuities observed between humans and other great apes in terms of complex tool use, language and ritual, all of which involve the cultural learning of novel arbitrary sequences. This article is part of the theme issue 'Ritual renaissance: new insights into the most human of behaviours'.

Only domain-specific imitation practice makes imitation perfect.

Does imitation involve specialized mechanisms or general-unspecialized-learning processes? To address this question, preschoolers (3- and 4-year-olds) were assigned to one of four "practice" groups. Before and after the practice phases, each group was tested on a novel Spatial Imitation sequence. During the practice phase, children in the Spatial Imitation group practiced jointly attending, vicariously encoding, and copying the novel spatial sequences. In the Item Imitation group, children practiced jointly attending, vicariously encoding, and copying novel item sequences. In the Trial-and-Error group, children practiced encoding and recalling a series of novel spatial sequences entirely through individual (operant) learning. In the Free Play (no practice) control group, children played a touchscreen drawing game that controlled for practice time on the touchscreen and mirrored some of the same actions and responses used in the experimental conditions. Results of the difference between pre- and post-practice effects on novel spatial imitation sequences showed that only the Spatial Imitation practice group significantly improved relative to the Free Play group. Individual Spatial Trial-and-Error practice did not significantly improve spatial imitation. The effect of Item Imitation practice was intermediate. These results are inconsistent with the hypothesis that general processes alone--or primarily--support imitation learning and is more consistent with a mosaic model that posits an additive-interaction-effect on imitation performance where a more general social cognitive mechanism (i.e., natural pedagogy) gathers the relevant information from the demonstration and another more specialized mechanism (i.e., imitation specific) transforms that information into a matching response.

The cognitive structure of goal emulation during the preschool years.

Humans excel at mirroring both others' actions (imitation) as well as others' goals and intentions (emulation). As most research has focused on imitation, here we focus on how social and asocial learning predict the development of goal emulation. We tested 215 preschool children on two social conditions (imitation, emulation) and two asocial conditions (trial-and-error and recall) using two touch screen tasks. The tasks involved responding to either three different pictures in a specific picture order (Cognitive: apple→boy→cat) or three identical pictures in a specific spatial order (Motor-Spatial: up→down→right). Generalized linear models demonstrated that during the preschool years, Motor-Spatial emulation is associated with social and asocial learning, while cognitive emulation is associated only with social learning, including motor-spatial emulation and multiple forms of imitation. This result contrasts with those from a previous study using this same data set showing that motor-spatial and cognitive imitation were neither associated with one another nor, generally, predicted by other forms of social or asocial learning. Together, these results suggests that while developmental changes in imitation are associated with multiple - specialized - mechanisms, developmental changes in emulation are associated with age-related changes and a more unitary, domain-general mechanism that receives input from several different cognitive and learning processes, including some that may not necessarily be specialized for social learning.

Becoming a high-fidelity - super - imitator: what are the contributions of social and individual learning?

In contrast to other primates, human children's imitation performance goes from low to high fidelity soon after infancy. Are such changes associated with the development of other forms of learning? We addressed this question by testing 215 children (26-59 months) on two social conditions (imitation, emulation) - involving a demonstration - and two asocial conditions (trial-and-error, recall) - involving individual learning - using two touchscreen tasks. The tasks required responding to either three different pictures in a specific picture order (Cognitive: Airplane→Ball→Cow) or three identical pictures in a specific spatial order (Motor-Spatial: Up→Down→Right). There were age-related improvements across all conditions and imitation, emulation and recall performance were significantly better than trial-and-error learning. Generalized linear models demonstrated that motor-spatial imitation fidelity was associated with age and motor-spatial emulation performance, but cognitive imitation fidelity was only associated with age. While this study provides evidence for multiple imitation mechanisms, the development of one of those mechanisms - motor-spatial imitation - may be bootstrapped by the development of another social learning skill - motor-spatial emulation. Together, these findings provide important clues about the development of imitation, which is arguably a distinctive feature of the human species.

Tool use by aquatic animals.

Tool-use research has focused primarily on land-based animals, with less consideration given to aquatic animals and the environmental challenges and conditions they face. Here, we review aquatic tool use and examine the contributing ecological, physiological, cognitive and social factors. Tool use among aquatic animals is rare but taxonomically diverse, occurring in fish, cephalopods, mammals, crabs, urchins and possibly gastropods. While additional research is required, the scarcity of tool use can likely be attributable to the characteristics of aquatic habitats, which are generally not conducive to tool use. Nonetheless, studying tool use by aquatic animals provides insights into the conditions that promote and inhibit tool-use behaviour across biomes. Like land-based tool users, aquatic animals tend to find tools on the substrate and use tools during foraging. However, unlike on land, tool users in water often use other animals (and their products) and water itself as a tool. Among sea otters and dolphins, the two aquatic tool users studied in greatest detail, some individuals specialize in tool use, which is vertically socially transmitted possibly because of their long dependency periods. In all, the contrasts between aquatic- and land-based tool users enlighten our understanding of the adaptive value of tool-use behaviour.

Social networks reveal cultural behaviour in tool-using [corrected] dolphins.

Animal tool use is of inherent interest given its relationship to intelligence, innovation and cultural behaviour. Here we investigate whether Shark Bay bottlenose dolphins that use marine sponges as hunting tools (spongers) are culturally distinct from other dolphins in the population based on the criteria that sponging is both socially learned and distinguishes between groups. We use social network analysis to determine social preferences among 36 spongers and 69 non-spongers sampled over a 22-year period while controlling for location, sex and matrilineal relatedness. Homophily (the tendency to associate with similar others) based on tool-using status was evident in every analysis, although maternal kinship, sex and location also contributed to social preference. Female spongers were more cliquish and preferentially associated with other spongers over non-spongers. Like humans who preferentially associate with others who share their subculture, tool-using dolphins prefer others like themselves, strongly suggesting that sponge tool-use is a cultural behaviour.

Look, no hands!

Contrary to Vaesen's argument that humans are unique with respect to nine cognitive capacities essential for tool use, we suggest that although such cognitive processes contribute to variation in tool use, it does not follow that these capacities are necessary for tool use, nor that tool use shaped cognition per se, given the available data in cognitive neuroscience and behavioral biology.

The ecological conditions that favor tool use and innovation in wild bottlenose dolphins (Tursiops sp.).

Dolphins are well known for their exquisite echolocation abilities, which enable them to detect and discriminate prey species and even locate buried prey. While these skills are widely used during foraging, some dolphins use tools to locate and extract prey. In the only known case of tool use in free-ranging cetaceans, a subset of bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia habitually employs marine basket sponge tools to locate and ferret prey from the seafloor. While it is clear that sponges protect dolphins' rostra while searching for prey, it is still not known why dolphins probe the substrate at all instead of merely echolocating for buried prey as documented at other sites. By 'sponge foraging' ourselves, we show that these dolphins target prey that both lack swimbladders and burrow in a rubble-littered substrate. Delphinid echolocation and vision are critical for hunting but less effective on such prey. Consequently, if dolphins are to access this burrowing, swimbladderless prey, they must probe the seafloor and in turn benefit from using protective sponges. We suggest that these tools have allowed sponge foraging dolphins to exploit an empty niche inaccessible to their non-tool-using counterparts. Our study identifies the underlying ecological basis of dolphin tool use and strengthens our understanding of the conditions that favor tool use and innovation in the wild.

Thar she blows! A novel method for DNA collection from cetacean blow.

BACKGROUND: Molecular tools are now widely used to address crucial management and conservation questions. To date, dart biopsying has been the most commonly used method for collecting genetic data from cetaceans; however, this method has some drawbacks. Dart biopsying is considered inappropriate for young animals and has recently come under scrutiny from ethical boards, conservationists, and the general public. Thus, identifying alternative genetic collection techniques for cetaceans remains a priority, especially for internationally protected species. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we investigated whether blow-sampling, which involves collecting exhalations from the blowholes of cetaceans, could be developed as a new less invasive method for DNA collection. Our current methodology was developed using six bottlenose dolphins, Tursiops truncatus, housed at the National Aquarium, Baltimore (USA), from which we were able to collect both blow and blood samples. For all six individuals, we found that their mitochondrial and microsatellite DNA profile taken from blow, matched their corresponding mitochondrial and microsatellite DNA profile collected from blood. This indicates that blow-sampling is a viable alternative method for DNA collection. CONCLUSION/SIGNIFICANCE: In this study, we show that blow-sampling provides a viable and less invasive method for collection of genetic data, even for small cetaceans. In contrast to dart biopsying, the advantage of this method is that it capitalizes on the natural breathing behaviour of dolphins and can be applied to even very young dolphins. Both biopsy and blow-sampling require close proximity of the boat, but blow-sampling can be achieved when dolphins voluntarily bow-ride and involves no harmful contact.