Interaction between the first farmers and the pre-existing population of Europe has always been thought to be unlikely. Farmers tended to set down roots and claim parcels of territory for themselves. Perhaps we are coloured by the history of N America where droves of farmers ploughed up the High Plains and disrupted the native lifestyle. However, the conflict there was mostly about broken promises and treaties that were a bit of a con trick. At www.eurekalert.org/pub_releases/2013-08/du-eho082713.php … evidence of domesticated pigs has been found, aquired by Mesolithic hunter gatherer communities as early as 4600BC. This is when the early farmers were spreading through central Europe. Was it a matter of cultural exchange? Were the natives really unwilling to learn new tricks? Conversely, could it be evidence of early farmers going native – as a result of climatic changes, catastrophic events such as bolides exploding in the atmosphere, or simply because some people thought it was a good way of life (combining some of their own traditions with those of the native lifestyle).
Evidence from Star Carr suggests Mesolithic people were not nomadic but had semi permanent settlements – and adopting a domesticated pig in favour of a beligerent local wild boar makes sense. This could even be regarded as a first step in the adoption of herding livestock (domestic cattle and sheep in preference to wild herds of red deer). The same applies to cereal cultivation, or legumes. If you were living in a semi permanent, perhaps seasonal, location, why not grow your own food. It may be that there was some kind of catalyst to encourage them to do this – a shortage of wild animals. Here is where landscape fires associated with atmospheric meteor events may have lent a helping hand. This was of course suggested in SIS pages years ago – back in the late 1970s.