In search of the last common ancestor: new findings on wild chimpanzees

摘要

Modelling the behaviour of extinct hominins is essential in order to devise useful hypotheses of ournspecies’ evolutionary origins for testing in the palaeontological and archaeological records. Onenapproach is to model the last common ancestor (LCA) of living apes and humans, based on currentnethological and ecological knowledge of our closest living relations. Such referential modelling isnbased on rigorous, ongoing field studies of the chimpanzee (Pan troglodytes) and the bonobo (Pannpaniscus). This paper reviews recent findings from nature, focusing on those with direct implicationsnfor hominin evolution, e.g. apes, using elementary technology to access basic resources such as foodnand water, or sheltering in caves or bathing as thermoregulatory adaptations. I give preference tonstudies that directly address key issues, such as whether stone artefacts are detectible before the Old-nowan, based on the percussive technology of hammer and anvil use by living apes. Detailedncomparative studies of chimpanzees living in varied habitats, from rainforest to savannah, revealnthat some behavioural patterns are universal (e.g. shelter construction), while others shownmarked (e.g. extractive foraging) or nuanced (e.g. courtship) cross-populational variation. Thesenfindings allow us to distinguish between retained, primitive traits of the LCA versus derived onesnin the human lineage.