From the whole article we get;
More recently, experts have proposed a third hypothesis: The Spanish flu originated somewhere in northern China in late 1917...
That's it, not a word more. That's the "proof".
Well my mate Andy knows a bloke down 'Spoons who has a budgie called Gary and he says it started in a whorehouse in Halifax - the bloke said it, not the budgie. At least I think that's it, but it could've been the budgie as he's an expert.
As for wet markets: I was reading a PDF about them with no C & P available.
It refers to hot countries in and around the tropics. Basically the markets go back to the time before we had electricity and fridges. A live animal, chicken, goat, lamb, fish, was chosen and slaughtered there and then. The carcass was taken home and immediately cooked or preserved because if that was not done it would soon rot. Today's markets are a throwback to those times and still necessary in some places.
Even those of us in cooler climes once had open livestock markets and used preserving methods for the foods we could not eat there and then, it's how we got all those cheeses, hams, salted beef, and smoked or dried sausages and fish.
I also remember a local grocer who had rabbits, hares, partridge, pheasant and ducks hung up in the window. They were all fully clothed but also very dead. Not ready-meals by any stretch and also a bit 'wild', as is most of the venison in the UK. In N. America they hunt, shoot and eat bear, buffalo, elk, moose, caribou, raccoons, possums, and alligator, among other things, so let's not get too hung up on this wild meat thing. And many of us get through quite a bit of non-farmed (wild) fish and shellfish, which is probably healthier than the farmed stuff anyway.
But I digress. it's all China's fault - 100%. The natural world plays no part whatsoever.