Adaptive Responses to Adversity Drive Innovation in Human Evolutionary History

Thinking is costly. Nonetheless, humans develop novel solutions to problems and share that knowledge prosocially. We propose that adversity, not prosperity, created a dependence on innovation in our ancestors who were forced through fitness valleys to develop new behaviors, which shaped our life history characteristics and a new evolutionary trajectory. Driven by competitive exclusion into novel habitats, and unable to reduce costs associated with finding appropriate food sources once there, our Pliocene ancestors adopted a diet different from our forest-dwelling great ape cousins. In a reimagining of classic foraging models we outline how those individuals, pushed into an ecotone with lower fitness, climbed out of the fitness valley by shifting to a diet dependent on extractive foraging. By reducing handling costs through gregarious foraging and emergent technology, our ancestors would have been able to find new optima on the fitness landscape, decreasing mortality by reducing risk and increasing returns, leading to extended life cycles and social reliance.