I don't see any support in that paper for the idea that Neanderthal DNA doesn't show that it's a different species. On the contrary. What the paper describes is

I don't see any support in that paper for the idea that Neanderthal DNA doesn't show that it's a different species. On the contrary. What the paper describes is the very well known theory that (modern) humans went through a near-fatal population bottleneck in the not too distant past, which means that the human genetic diversity is so low that two people from different sides of the earth have less genetic variation between them than two chimpanzees from different sides of the river in a single forest have between them.