Over at Science at this LINK. Broadly speaking, this looks like a more sophisticated version of something that I tried about five years ago (see here).
I wonder if they got the idea from me? Honestly, I wouldn't be surprised if they did. But like I say, their methods are way more advanced.
Keep in mind, however, that for now, their analysis includes 3601 modern genomes and just eight ancient genomes. That's because they can only run super high quality ancient sequences. The ratio of ancient genomes will no doubt rise rapidly over the next few years, and that's when things will get really interesting.
Below are some screen caps from a clip accompanying the paper, freely available here. This is the caption to the movie:
Spatio-temporal dynamics in human history. This movie shows the estimated geographic locations of ancestors of Human Genome Diversity Project, Simons Genome Diversity Project, Neanderthal, Denisovan, and Afanasievo samples over time. Each dot represents an edge in the tree sequence of chromosome 20, where the time and geographic location of the parent and child nodes of the edge have been estimated. The locations of edges at each point in time are plotted along the great circle between the parent and child nodes. Edges are colored by the region of the descendants of the child node. If an ancestral lineage has ancestors in multiple regions, its color is the average of the respective colors of each region.
See also...
Haplotype-based PCA of West Eurasia and Europe