Figure 1. Estimating the time of divergence between human and chimpanzee relies on a calibration based on a known divergence time – in this case either the hominine–pongine split or the hominoid–cercopithecoid split. Note the taxonomy used herein.

Figure 2. Hypothetical species divergence leading to extant taxa (species 1–3) and fossils used to date the calibration node (A–E).

Figure 3. The current state of knowledge regarding the hominin fossil record (left) surrounding the human–chimpanzee divergence, compared to divergence dates from molecular data (right). Fossil species are taken from Wood (2006), references therein, and the more recent primary literature. Molecular dates are largely taken from Steiper and Young (2006, p. 390 their Table 4), removing dates not based on DNA sequence data, and adding the dates from Hasegawa et al. (1985) and Patterson et al. (2006). Open circles represent divergence dates as estimated in the original publications (or means if ranges were given); closed circles are the same dates standardized by assuming a 30.5-Mya divergence between hominoids and cercopithecoids or an 18.3-Mya divergence between humans and orangutans (Steiper and Young, 2006).