Emotional engagements predict and enhance social cognition in young chimpanzees

Social cognition in infancy is evident in coordinated triadic engagements, that is, infants attending jointly with social partners and objects. Current evolutionary theories of primate social cognition tend to highlight species differences in cognition based on human-unique cooperative motives. We consider a developmental model in which engagement experiences produce differential outcomes. We conducted a 10-year-long study in which two groups of laboratory-raised chimpanzee infants were given quantifiably different engagement experiences. Joint attention, cooperativeness, affect, and different levels of cognition were measured in 5- to 12-month-old chimpanzees, and compared to outcomes derived from a normative human database. We found that joint attention skills significantly improved across development for all infants, but by 12 months, the humans significantly surpassed the chimpanzees. We found that cooperativeness was stable in the humans, but by 12 months, the chimpanzee group given enriched engagement experiences significantly surpassed the humans. Past engagement experiences and concurrent affect were significant unique predictors of both joint attention and cooperativeness in 5- to 12-month-old chimpanzees. When engagement experiences and concurrent affect were statistically controlled, joint attention and cooperation were not associated. We explain differential social cognition outcomes in terms of the significant influences of previous engagement experiences and affect, in addition to cognition. Our study highlights developmental processes that underpin the emergence of social cognition in support of evolutionary continuity

Nonconstant electronic density of states tunneling inversion for A15 superconductors: Nb3Sn

We re-examine the tunneling data on A15 superconductors by performing a generalized McMillan-Rowell tunneling inversion that incorporates a nonconstant electronic density of states obtained from band-structure calculations. For Nb3Sn, we find that the fit to the experimental data can be slightly improved by taking into account the sharp structure in the density of states, but it is likely that such an analysis alone is not enough to completely explain the superconducting tunneling characteristics of this material. Nevertheless, the extracted Eliashberg function displays a number of features expected to be present for the highest quality Nb3Sn samples.Comment: 11 pages, 11 figure

Target animacy influences chimpanzee handedness

We employed a bottom-up, quantitative method to investigate the origins of great ape handedness. Our previous investigation of gorillas (Gorilla gorilla gorilla) demonstrated that contextual information influenced an individual’s handedness towards target objects. Specifically, we found a significant right-hand bias for unimanual actions directed towards inanimate target objects but not for actions directed to animate target objects (Forrester et al. 2011). Using the identical methodological technique, we investigated the spontaneous hand actions of nine captive chimpanzees (Pan troglodytes) during naturalistic, spontaneous behavior. We assessed both the frequencies and proportions of lateralized hand actions directed towards animate and inanimate targets employing focal follow video sampling. Like the gorillas, the chimpanzees demonstrated a right-handed bias for actions directed towards inanimate targets, but not towards animate targets. This pattern was evident at the group level and for the majority of subjects at the individual level. We postulate that a right hand bias for only inanimate targets reflects the left hemisphere’s dominant neural processing capabilities for objects that have functional properties (inanimate objects). We further speculate that a population-level right hand bias is not a human-unique characteristic, but one that was inherited from a common human-ape ancestor

Gorillas and chimpanzees vary handedness based on the animacy of target objects: a theory for hemispheric specialization based on an evolutionary distinction of object animacy

Birth in mammals is a crucial and delicate moment and it has been described in many species. Despite that, exhaustive descriptions of delivery in non-human primates are scarce. Moreover, in highly social animals there is a total lack of data on the reactions of other members of the group towards the mother and the newborn. This report describes a delivery in a captive group of bonobos (Pan paniscus) at Apenheul Primate Park (The Netherlands). Three observers followed the group: one of them collected data on the mother via focal animal sampling, the second one recorded the identities and behaviours of group members that were in proximity to the mother, and the third video-recorded the whole event, which lasted about a hour. The mother performed the characteristic squatting posture during contractions, touched her vaginal area and moved her hands from the vagina to the mouth and licked her fingers. Two adult, one ju venile, and one infant female were extremely interested in the mother and the newborn: they followed and frequently touched her. Males and the other pregnant female never approached the mother before the birth took place. We also observed the consumption of the placenta and its sharing among group members. Although the other pregnant female was one of the most important females in the group, she was never in proximity to the mother and she neither asked for the placenta nor received it

The Evolution of Primate Communication and Metacommunication

Against the prior view that primate communication is based only on signal decoding, comparative evidence suggests that primates are able, no less than humans, to intentionally perform or understand impulsive or habitual communicational actions with a structured evaluative nonconceptual content. These signals convey an affordance‐sensing that immediately motivates conspecifics to act. Although humans have access to a strategic form of propositional communication adapted to teaching and persuasion, they share with nonhuman primates the capacity to communicate in impulsive or habitual ways. They are also similarly able to monitor fluency, informativeness and relevance of messages or signals through nonconceptual cues

Assertion-based encapsulation, object invariants and simulations

Abstract. In object-oriented programming, reentrant method invocations and shared references make it difficult to achieve adequate encapsulation for sound modular reasoning. This tutorial paper surveys recent progress using auxiliary state (ghost fields) to describe and achieve encapsulation. Encapsulation is assessed in terms of modular reasoning about invariants and simulations.