Humans live in equilibrium with other species in a finite world. In such a world, there is never really a Steady State. Instead, there is a constant ebb and flow.  For a while, one species may be dominant in an area, and then another. If populations are closely matched in “ability,” then the ups and downs aren’t too severe. If a predator depends on a particular type of prey for its dinner, it can’t eat all of the prey, or it will go hungry.

When the populations of various species are graphed, they rise and fall.  We usually think of a close match, such as depicted in this graph:

Figure 1. Volterra_Lotka equations used to illustrate situation where population of predators and prey do not vary over too wide a range.Source: Wikipedia.

In fact, the variability of the many species over time tends to be greater than this, as illustrated by the following model that started with 80 baboons and 40 cheetahs:

Figure 2. Lotka-Volterra equations used to illustrate situation that begins with 80 baboons and 40 cheetahs. Source: Wikipedia

If species evolve together, a natural balance tends to remain in place. Continue reading →