Ape Cognition

Biological anthropologists use the comparative perspective in their efforts to reconstruct human evolutionary history. As our closest living relatives, primates are often used to frame comparisons and to test hypotheses about various human features. A feature (behavioral, genetic, or anatomical) that appears in all primate species is at least initially assumed to also characterize the last common ancestor of those species; features present in only one form presumably evolved at some point after it diverged, and hypotheses explaining the features are developed in the context of unique aspects of the organism's ecology and anatomy. The large-bodied apes (orangutans, gorillas, chimpanzees, and bonobos)are most closely related to humans, so those species, particularly chimpanzees, are the preferred ones to compare to fossil and living humans. However, comparisons between humans and other more distantly related species are also informative and serve to demonstrate instances of evolutionary convergences (similar selective pressures lead to similar outcomes in distantly related forms) or features that evolved before the ape/human split as our primate or mammalian heritage.

Students of Darwin assume continuity between species, and they use a comparative approach to understand biology, behavior, and cognition of primates. These evolutionary anthropologists predict that few traits, including cognitive ones, will arise de novo—evolutionary precursors are the norm. In contrast, cultural anthropologists have sometimes focused on the uniqueness of the human mind, particularly with respect to language and culture, and assume gaps in the phylogenetic scale.

The dictionary defines cognition as “the act or process of knowing, including both awareness and judgment; also a product of this act.” These constructs are impossible to observe in humans and nonhumans; thus researchers are left with studying behaviors and defining those behaviors as indicators of a particular cognitive function. The methods of observation and the definitions of behaviors should be used consistently across species to increase the validity of comparisons.

Primatologists are scientists who study the behavior, biology, and evolution of nonhuman primates. The field of primatology draws from individuals trained as psychologists, biologists, or anthropologists, and one's training has a profound impact on research questions asked. Traditionally, primatologists trained as anthropologists studied wild nonhuman primates and used resulting data to model hominids and to better understand modern humans. Primatologists trained as psychologists focused more heavily on cognitive processes, intelligence, and language and usually explored these topics using captive nonhuman primates where experimental conditions are more easily controlled.

Here we trace the quest to understand, however imperfectly, the ape mind. The study of ape cognitive abilities includes research conducted with captive individuals, where more precise control over experimental and rearing conditions are possible, and individuals living in the wild, where relationships [Page 208]between particular cognitive abilities and aspects of the organism's environment can more readily be explored.