The existence of low-level food producers, neither wholly hunter-gatherers nor wholly agriculturalists, is predicted but hard to prove. Here the authors use lithics, the one ubiquitous common indicator, to show how the detection of missing flakes can indicate degrees of mobility, while mobility in turn shows how people coped with the unpredictable appearance of food resources. In Australia, they were opportunists, armed with a ready cutting edge. In the Fayum, they had less far to go, but still roamed ; http://www.ioa.ucla.edu/news-events/files/Holdaway_etal_2010.pdf