Introduction: The problem of reconstructing cognition
Most psychologists and cognitive scientists and almost all linguists investigate the nature of the mind, intelligence, and language from a uniquely human perspective. But the origins of these attributes lie in the deep history of the primate brain, and all organic explanations for them must derive from non-human and human primate evolutionary history. There are a variety of approaches to reconstructing the origins of cognition and language. The fossil record is the only direct evidence of human evolution, but it is fragmentary. It can tell us little about the roots of cognition and language because the soft tissues involved do not fossilize.
Our understanding of human evolution is therefore greatly enhanced by evidence from living primates, especially those most closely related to us, the great apes – the chimpanzee (Pan troglodytes), bonobo (P. paniscus), gorilla (Gorilla gorilla), and orangutan (Pongo pygmaeus). While we must be careful not to consider apes as living fossils, they are exemplars of the way in which natural selection molds large-brained, social primates to the natural environment. They exhibit learned, interpopulational culturally varied behavior beyond that of any animal other than ourselves. They provide us with a sense of the likeliest range of options, behavioral and cognitive, that natural selection would have taken with ancestral forms of humans.
As an anthropologist, I study non-human primates because they inform us about the likely course that the evolution of human form and function has taken.