Figure 3. Life history traits as functions of per capita energy use.

(a) The lifespan and its major divisions for industrial populations (nations). (b) Reproductive delay (age at menarche - age at first reproduction) varies similarly with per capita energy use among nonhuman primates and industrial human populations. The dashed line is a linear fit to the combined datasets, nonhuman primates and industrial nations. (c) The net reproductive rate for industrial populations. Horizontal dotted line drawn at log(R₀) = 0. Growing populations are above the line and declining populations are below it (not accounting for migration or other dynamics). (d) Probability of survival to age five for industrial populations. Median value of energy use indicated with the dashed line.