Cognitive demands of bipedal locomotion during human foraging.

Human foraging requires cognitive and physical demands that influence each other. These demands include challenges of staying upright while walking bipedally in complex environments, along with other cognitive tasks (e.g. navigation, executive functions). The combination of cognition and movement is known as cognitive-motor dual-tasks, which can result in declines in performance. However, the influence of cognitive-motor dual-tasks has not been observed in ecologically relevant settings. By using a laboratory-based experiment with 45 healthy participants, as well as observations from foraging bouts with the Hadza, a hunter-gatherer population living in northern Tanzania, we tested the hypothesis that walking over uneven terrain and cognitive challenges interfere with both locomotor and cognitive performance. In the laboratory-based experiment, walking over uneven terrain and walking with the cognitive-motor dual-task were associated with a reduction in stride frequency. Additionally, dual-task walking was associated with worse cognitive performance on both the flat surface and a further reduction on the uneven surface. In Hadza participants, engaging in verbal communication and walking over uneven terrain were negatively associated with stride frequency. Our findings highlight the interplay between cognition and locomotion in ecologically relevant foraging contexts, suggesting that cognitive demands may serve as a constraint on human mobility in complex environments.