In this case they have carbon dated wooden equipment for fish farming and know due to geological factors when the lake could support fish, though of course the fish might have gotten there first somehow. I thought this was interesting because it predates agriculture in the same area.
Humans were shaping their environments to produce food long before they plowed fields. Hunter-gatherers didn't just hunt and gather willy-nilly, picking up whatever they found, oblivious to how it got there.
Yeah, you have to consider that when you're living in nature you actually need to identify the plants that are edible so you can't actually just eat everything you find even if you could eat it in theory.
So if you wanted to gather plant food how do you make sure that the food you find is edible?
It's quite simple. If you know a plant is edible you take the seeds and you carry them with you and broadcast them all over the place.
The interesting part about this is that this is also a form of selective breeding, since you're choosing the edible plants over the inedible plants.
Note that you do not tend to the plants or do any form of agriculture, you're still foraging from random plants you encounter.
It blows my tiny wee Homo just-about-Sapiens mind that I have this brain which evolved to travel at walking pace for a few hours and think in terms of "you get loads of rabbits about an hour's walk from here behind those hills, and the really good berries are that way down towards the river".
And yet despite that it can quite happily plan out and navigate a route that is hundreds of miles long, at roughly 20 times the speed it was designed to travel at.
I'm sitting here writing a text message to someone 1800 miles away giving them directions to a shop in Vienna and I can visualise where they need to go for that to all work, with a brain that evolved to think about "not the next hill but the one after that" distance.
Artifacts that survive this long are usually found in a buried context, which can, under favorable conditions, preserve them for long periods of time.
The artifact can be buried by colluvial(gravity driven), or alluvial(water driven) deposition before they have a chance to decay. For more information you can consult a geomorphologist, which I am not.
Intact human bodies thousands of years old have been found in Irish bogs - cold, anoxic, acidic. Apparently in this case cold and anoxic were part of it, and also pine resin in the wood acting as a perservative.
In the peat bogs on Skye where I grew up and where people still cut peat for fuel, you often see the remains of silver birch trees that must have grown a couple of thousand years ago.
They're often so well-preserved that not only can you clearly see the markings on the bark but you can sometimes make out the rings in the wood.
I remember my dad pulling out a piece that was so well preserved you could see where deer had gnawed it.
