The team then created a Markov chain Monte Carlo simulation to estimate and date the phylogenetic trees of the seven language families under examination. Five separate runs produced the same (unrooted) tree, with three sets of language families: an eastern grouping of Altaic, Inuit–Yupik, and Chukchi–Kamchatkan; a central and southern Asia grouping of Kartvelian and Dravidian; and a northern and western European grouping of Indo-European and Uralic. Two rootings were considered, using established age estimates for Proto-Indo-European and Proto-Chukchi–Kamchatkan as calibration. The first roots the tree to the midpoint of the branch leading to proto-Dravidian and yields an estimated origin for Eurasiatic of 14450 ± 1750 years ago. The second roots to tree to the proto-Kartvelian branch and yields 15610 ± 2290 years ago. Internal nodes have less certainty, but exceed chance expectations, and do not affect the top-level age estimate. The authors conclude "All inferred ages must be treated with caution but our estimates are consistent with proposals linking the near concomitant spread of the language families that comprise this group to the retreat of glaciers in Eurasia at the end of the last ice age ∼15,000 years ago."