400 Years in Motion: Mapping Ancestors' Displacements

I kinda thought it was weird that they made the dots travel, because it kinda suggests that it reflect the real travel time, but it made more sense after seeing all the dots that end up on screen. It's so you can track the individual dots instead of just seeing them appear and disappear. I still feel like there might be a better way to represent this, though, but I have no idea what. Anyway, I think this is good work, OP, if you did it. I don't imagine it was terribly easy. Care to share the development story?