Boxes are stocks - where a quantity is accumulated
Valves coming out, or going into, boxes are out- and in-flows.
Circles are auxiliary quantities or actions.
Area = The total area of the continent
M25 = The number of animal units per unit area
Regen K & Rate K = control of the carrying capacity for herbivores
K limit = Herbivore carrying capacity
B rate H = Birth rate of herbivores
Regen H = Regeneration rate of herbivores
Herb AU = Herbivores in animal units
Out H = Out flow of herbivores from the population
M1295 = The number of Homo sapiens per unit area
Regen HsL & Rate HsL = Control of the carrying capacity for Homo sapiens
Hs Limit = Homo sapiens carrying capacity
B rate Hs = Birth rate of Homo sapiens
Migration Pulse Hs = start time of Homo sapiens migration
Regen Hs = Regeneration rate of Homo sapiens
H. sapiens = Homo sapiens population level in individuals
H kill rate and Kill = the number of animals killed per unit of H. sapiens.
Diagram 1 - Using the values and relationships as specified by Whittington and Dyke (1989)
Each of the diagrams is the same save for the addition of an outflow from the Hs Limit box and its controller in Diagram 2. This represents the relationship between the death of herbivores, Out H, and the state of the carrying capacity of Homo sapiens, Hs Limit. In both diagrams the level of the Hs Limit box impacts the regeneration rate of Homo sapiens.