The human selection of food plants cannot always have been aimed exclusively at isolating the traits typical of domesticated species today. Each phase of global change must have obliged plants and humans to cope with and develop innovative adaptive strategies. Hundreds of thousands of wild cereal seeds from the Holocene 'green Sahara' tell a story of cultural trajectories and environmental instability revealing that a complex suite of weediness traits were preferred by both hunter-gatherers and pastoralists. The archaeobotanical record of the Takarkori rockshelter in southwest Libya covering four millennia of human occupation in the central Sahara gives us a unique insight into long-term plant manipulation and cultivation without domestication. The success of a number of millets was rooted in their invasive-opportunistic behaviour, rewarded during their coexistence with people in Africa. These wild plants were selected for features that were precious in the past but pernicious for agriculture today. Reconnecting past practices with modern farming strategies can help us to seek out the best resources for the future.