Clearances, interpreted from pollen records during the Mesolithic and Neolithic of Europe, are generally ascribed to purposive deforestation which is compatible with the transition model, whereby early Neolithic economic strategies are a development of late Mesolithic intensification of wild plant food husbandry. This paper considers the role of natural processes in creating clearings and the role of inadvertent impact of human activity on forest processes, including woodland regeneration. The role of climate, wind-throw and lightning strikes in creating clearings and forest instability is emphasised and the evidence discussed from sites which may be interpreted as resulting from opportunistic human use of natural clearings. Unfortunately, regional pollen diagrams lack sufficient spatial resolution to detect the size of isolated clearings or establish the spatial variation in forest composition that was intimately related both to forest ecology and the effects of subtle human impacts. This may be the major reason for an apparent contradiction between pollen evidence of Neolithic impact and the archaeological record. Moreover, early Neolithic agricultural activity may have been concentrated in valley bottoms, which is undetectable in regional pollen diagrams. Alternative models need to be considered, which include culturally specific exploitation of the local environment, along with the inadvertent ecological repercussions of pre-agricultural and early-agricultural human activities in naturally dynamic woodlands.