Interesting piece. Anyone who sees this as significant “news” is however missing what race and species really are and the fact that they’re not really very well defined objects. A species exists only if and so long as it cannot successfully interbreed with another, and the experience of a line of individuals is something quite different to the average statistical patterns of a population.
The branching and re-merging picture of the “muddy delta” from the article is about genetic distributions:
The branching-only tree view only applies to things we choose to call species, with hindsight and with some presumed good reason.
But, genetic material in DNA mixes with breeding – that’s a network of relations individually and population-wise over time – and only a small part of the genetic payload is significant in determining what might lead us to name a race or species. The vast majority of that payload is simply dispersed through the breeding networks. A second small proportion may be important to features of the individuals even if not the initial tiny portion that determines a race or species, but both are small compared to the genetic baggage that comes along for the ride.