| Abstract: | Although chimpanzees generally grasp small objects imprecisely between the knuckle joint of the index finger and thumb, they are capable of a true precision grip, which resembles the human pincer grip. They also grip small objects between the index and middle finger. The development of these precision grips takes place over several years into adulthood and they are not frequent before 8 years of age. Precision grips and imprecise grips are equally likely to be selected for objects of small size. Thus, not only is precise prehension relatively delayed in chimpanzees but also there is lack of consistency in selecting the distal parts of the index finger for thumb opposition. This is a qualitatively different developmental pattern than occurs in human infants who systematically select precision grips for small objects by 15 months. |
