Inferred origin and diffusion of the Ainu language varieties in natural time scale.Color gradient of the polygons (80% HPD) indicates relevant age of the diffusion [Blue-older (1288 BP); Red-more recent (50 BP)]. White lines represent the phylogeny projected onto the surface. Image sources: ? 2012 Google Earth; ? 2012 Cnes/Spot Image; ? 2012 TerraMetrics.