Differences in the early cognitive development of children and great apes. 
There is very little research comparing great ape and human cognition developmentally.  In the current studies we compared a cross-sectional sample of 2- to 4-year-old human children (n=48) with a large sample of chimpanzees and bonobos in the same age range (n=42, hereafter: apes) on a broad array of cognitive tasks.  We then followed a group of juvenile apes (n=44) longitudinally over 3 years to track their cognitive development in greater detail.  In skills of physical cognition (space, causality, quantities), children and apes performed comparably at 2 years of age, but by 4 years of age children were more advanced (whereas apes stayed at their 2-year-old performance levels).  In skills of social cognition (communication, social learning, theory of mind), children out-performed apes already at 2 years, and increased this difference even more by 4 years.  Patterns of development differed more between children and apes in the social domain than the physical domain, with support for these patterns present in both the cross-sectional and longitudinal ape data sets.  These results indicate key differences in the pattern and pace of cognitive development between humans and other apes, particularly in the early emergence of specific social cognitive capacities in humans.