9. The heterochronic origins of explicit reference
Explicit reference is the communicative capacity to intentionally pick out a specific object in the environment and make that object a manifest topic for shared attention. Pointing is the quintessential example of non-verbal, explicit reference. Chimpanzees, and other apes in captivity, spontaneously point without overt training. Because wild apes almost never point, and because both captive and wild apes are sampled from the same gene pool, this implies that, for apes, hominoid genes interact with certain environments to elicit pointing. We propose that changes in the patterns of hominid development interact with ape-like cognitive capacities to produce features of explicit reference in human infants, a capacity that emerges in our nearest living relatives when they experience similar circumstances.