I suppose it's worthwhile to come up with evidence that supports what seems obvious, but evidence has been found that indicates hunter-gatherers engaged in animal trade/theft/capture with Neolithic settlements.First evidence that European hunter-gatherers owned pigs discoveredThe reason I say this is obvious is because it is; the article says the evidence dates to 6600 years ago - 4600 B.C. - when several permanent Neolithic settlements had already been in existence for thousands of years.  It only makes sense that as nomads came into contact with settlements, they would have relied on these settlements at least in part because of the advantage they provided over the nomadic way of life.  There's a reason why hunter-gathering died out after the ice receded from Europe; it's easier and more efficient to raise animals in pens and harvest crops near a constant supply of water than it is to move from place to place every so often.