FIGURE 1. Consensus tree and divergence-time estimates.

a, Majority-rule consensus tree based on the MCMC sample of 1,000 trees. The main language groupings are colour coded. Branch lengths are proportional to the inferred maximum-likelihood estimates of evolutionary change per cognate. Values above each branch (in black) express the bayesian posterior probabilities as a percentage. Values in red show the inferred ages of nodes in years BP. *Italic also includes the French/Iberian subgroup. Panels b–e show the distribution of divergence-time estimates at the root of the Indo-European phylogeny for: b, initial assumption set using all cognate information and most stringent constraints (Anatolian, Tocharian, (Greek, Armenian, Albanian, (Iranian, Indic), (Slavic, Baltic), ((North Germanic, West Germanic), Italic, Celtic))); c, conservative cognate coding with doubtful cognates excluded; d, all cognate sets with minimum topological constraints (Anatolian, Tocharian, (Greek, Armenian, Albanian, (Iranian, Indic), (Slavic, Baltic), (North Germanic, West Germanic), Italic, Celtic)); e, missing data coding with minimum topological constraints and all cognate sets. Shaded bars represent the implied age ranges under the two competing theories of Indo-European origin: blue, Kurgan hypothesis; green, Anatolian farming hypothesis. The relationship between the main language groups in the consensus tree for each analysis is also shown, along with posterior probability values.