ABSTRACT
Living primates can be used to reconstruct some behavior of the Last Common Ancestor (LCA). Relevant models can be grouped into the overlapping categories of referential, conceptual, and functional models. These analogical models may use a particular taxon for reconstruction, based on phylogenetic closeness to the hominin lineage. Chimpanzees and bonobos are pertinent to the LCA, but they differ significantly in some of their behavior. Even where they are similar, the behavior in question might have evolved after their lineage separated from ours. A solution to this problem is to use larger phylogenetic samples that represent common ancestors earlier than the LCA. Arboreal behavior might have persisted in the wooded components. The descriptions of primate behavior are arranged under: ecology, sociality, life cycle, and cognition. The LCA must have eaten insects and possibly meat. The LCA probably lived in fission-fusion communities with social dynamics similar to those of bonobos or chimpanzees. Gestural communication may have been elaborate.
