Perturbations and fluctuations can range widely and include long-term climatic
shifts and oscillations, medium-term changes associated with El Niño–Southern
Oscillation events, seasonal variability, and minor everyday disturbances. Broader
political dynamics, such as wars (de Jong et al. 2007) and slave raiding in the
historical period (Endicott 1983) that dispersed and displaced populations, as well
as contemporary state policies of resettlement and assimilation (Benjamin and Chou
2002; Nicholas 2000; Scott 2009), also, of course, have implications for resource
availability