Prominent theorists have made the argument that modern humans express moral concern for a greater number of entities than at any other time in our past. Moreover, adults show stable patterns in the degrees of concern they afford certain entities over others, yet it remains unknown when and how these patterns of moral decision-making manifest in development. Children aged 4 to 10 years (N = 151) placed 24 pictures of human, animal, and environmental entities on a stratified circle representing three levels of moral concern. Although younger and older children expressed similar overall levels of moral concern, older children demonstrated a more graded understanding of concern by including more entities within the outer reaches of their moral circles (i.e., they were less likely to view moral inclusion as a simple in vs. out binary decision). With age children extended greater concern to humans than other forms of life, and more concern to vulnerable groups, such as the sick and disabled. Notably, children’s level of concern for human entities predicted their prosocial behavior. The current research provides novel insights into the development of our moral reasoning and its structure within childhood.

Young children typically demonstrate low rates of tool innovation. However, previous studies have limited children's performance by presenting tools with opaque affordances. In an attempt to scaffold children's understanding of what constitutes an appropriate tool within an innovation task we compared tools in which the focal affordance was visible to those in which it was opaque. To evaluate possible cultural specificity, data collection was undertaken in a Western urban population and a remote Indigenous community. As expected affordance visibility altered innovation rates: young children were more likely to innovate on a tool that had visible affordances than one with concealed affordances. Furthermore, innovation rates were higher than those reported in previous innovation studies. Cultural background did not affect children's rates of tool innovation. It is suggested that new methods for testing tool innovation in children must be developed in order to broaden our knowledge of young children's tool innovation capabilities.

Through the mechanisms of observation, imitation and teaching, young children readily pick up the tool using behaviours of their culture. However, little is known about the baseline abilities of children's tool use: what they might be capable of inventing on their own in the absence of socially provided information. It has been shown that children can spontaneously invent 11 of 12 candidate tool using behaviours observed within the foraging behaviours of wild non-human apes (Reindl et al . 2016 Proc. R. Soc. B 283 , 20152402. ( doi:10.1098/rspb.2015.2402 )). However, no investigations to date have examined how tool use invention in children might vary across cultural contexts. The current study investigated the levels of spontaneous tool use invention in 2- to 5-year-old children from San Bushmen communities in South Africa and children in a large city in Australia on the same 12 candidate problem-solving tasks. Children in both cultural contexts correctly invented all 12 candidate tool using behaviours, suggesting that these behaviours are within the general cognitive and physical capacities of human children and can be produced in the absence of direct social learning mechanisms such as teaching or observation. Children in both cultures were more likely to invent those tool behaviours more frequently observed in great ape populations than those less frequently observed, suggesting there is similarity in the level of difficulty of invention across these behaviours for all great ape species. However, children in the Australian sample invented tool behaviours and succeeded on the tasks more often than did the Bushmen children, highlighting that aspects of a child's social or cultural environment may influence the rates of their tool use invention on such task sets, even when direct social information is absent.

This study examined future-oriented behavior in children (3-6 years; N = 193) from three diverse societies-one industrialized Western city and two small, geographically isolated communities. Children had the opportunity to prepare for two alternative versions of an immediate future event over six trials. Some 3-year-olds from all cultures demonstrated competence, and a majority of the oldest children from each culture prepared for both future possibilities on every trial. Although there were some cultural differences in the youngest age groups that approached ceiling performance, the overall results indicate that children across these communities become able to prepare for alternative futures during early childhood. This acquisition period is therefore not contingent on Western upbringing, and may instead indicate normal cognitive maturation.

Over the last decade, the metacognitive abilities of nonhuman primates and the developmental emergence of metacognition in children have become topics of increasing research interest. In the current study, the performance of three adult chimpanzees (Pan troglodytes; Experiment 1) and forty-four 3.5- and 5.5-year-old human children (Experiment 2) was assessed on a behavioral search paradigm designed to assess metacognition. Subjects either directly observed the baiting of a large reward into one cup among an array of four, or had the baiting occluded from their view. In half of the trials, subjects were also presented with an additional distinctive cup that was always visibly baited with a small reward. This cup allowed subjects the opportunity to escape from making a guess about the location of the bigger reward. All three chimpanzees and both age groups of children selected the escape cup more often when the baiting of the large reward was concealed, compared to when it was visible. This demonstrates that both species can selectively choose a guaranteed smaller reward when they do not know the location of a larger reward and provides insight into the development of metacognition.

Prior research suggests that human children lack an aptitude for tool innovation. However, children’s tool making must be explored across a broader range of tasks and across diverse cultural contexts before we can conclude that they are genuinely poor tool innovators. To this end, we investigated children’s ability to independently construct 3 new tools using distinct actions: adding, subtracting, and reshaping. We tested 422 children across a broad age range from 5 geographic locations across South Africa (N = 126), Vanuatu (N = 190), and Australia (N = 106), which varied in their levels of exposure to Westernized culture. Children were shown a horizontal, transparent tube that had a sticker in its middle. Children were sequentially given each incomplete tool, which when accurately constructed could be used to push the sticker out of the tube. As predicted, older children were better at performing the innovation tasks than younger children across all cultures and innovation actions. We also found evidence for cultural variation: While all non-Western groups performed similarly, the Western group of children innovated at higher rates. However, children who did not innovate often adopted alternate methods when using the tools that also led to success. This suggests that children’s innovation levels are influenced by the cultural environment, and highlights the flexibility inherent in human children’s tool use.

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and Ikunala and Yakel and surrounding villages, who shared their time with us.Competing interests: The authors have no competing interests to declare.Author contributions: JD and MH originated the idea and developed the method. JD collected data in Peru, Vanuatu, and Australia and carried out the analyses. ER translated and collected data in Peru. SLL coordinated and collected data in the Republic of the Congo. KN, RK, and MN organized research in Vanuatu and Australia. MH supervised the project. JD and MH drafted the manuscript and the other authors edited and revised the manuscript.