Figure 5: Inferred IBD segments between various Copper & Bronze Age West Eurasian Groups.

We visualize IBD segments 12–16 centimorgan long (for IBD sharing in other length classes see Fig. E2). We applied ancIBD to identify IBD segments between all pairs of 304 West Eurasian ancient individuals (all previously published data, see Supp. Tab. 1c) organized into 24 Archaeological groups. For each pair of groups, we plot the fraction of all possible pairs of individuals that share at least one IBD 12–16 centimorgan long, which we obtained by dividing the total number of pairs that share such IBD segments by the total number of all possible pairs: Between two different groups of n₁ and n₂ individuals, one has n₁·n₂ pairs, while within a group (on the diagonal in the figure) of size n one has n(n – 1)/2 pairs.