Fellow travelers

Humans walked with companions. Anders Bergström et al., "Origins and genetic legacy of prehistoric dogs"; and Diego Forni, Rachele Cagliani, Mario Clerici, Uberto Pozzoli, Manuela Sironi, "You Will Never Walk Alone: Codispersal of JC Polyomavirus with Human Populations" doi 10.1093/molbev/msz227. h/t Whyvert.

I hadn't even heard of the JC Polyomavirus. I learn today that just about everyone got it. To the degree it affects humans, it's toward our baseline now. For harm I'd start with pregnancies; preemies went down under THE LOCKDOWN which translates to miscarriages in pre-ICU centuries. Maybe it hit Neanders and Dennies worse. Maybe they got a variant of it too and we swamped out that variant like we swamped them out.

I'd suggest the two are related like toxoplasma for cats, except that nobody sees this virus among dogs.

On to dogs, here's Razib Khan. He's always been good for pulling the most interesting facts from a paper and as his style has improved, he's good at laying it out for plebs (like me). He notes that most dogs today descend from a Neolithic mix also found 3000 BC Sweden.

Bergström's paper doesn't see wolf injections in those populations. The dog is considered to descend from a wolf subspecies but that wolf is no longer in the wild. There's a fertile Swiss dog/wolf hybrid - one starred Alpha - but that was bred deliberately and modernly, like the Beefalo^TM. The real trend was a feral dog joining a wolf-pack. The Red Wolf in North America today is part dog, part coyote and part American "Grey" wolf.

Populations kept their own dogs and didn't crossbreed them... much. But sometimes humans crossbred with humans. The Indo-European movement before the Battle Axe Culture is a case in point. So was that Swedish dog from Neolithic Farmers, or from a new protoGermanic aristocracy? I suspect the answer to that is "yes". The IndoEuropeans mixed (forceably) with Farmers along the Elbe, then moved across the Baltic into Sweden and imposed their Celt-like language. The old Scandinavian language survived as substrate, with its plethora of alien Baltic terms, as did many local men (I2); but the local dogs did not survive.