Douglas Harper's Etymology Dictionary
over-population
"over-populousness," 1807, from over- + population. Malthus (1798) had over-populousness.
Usage examples of "over-population".
After world war came the energy shortage, political leadership, terrorism, over-population, and pollution.
Over the whole extent of the South Seas, from one tropic to another, we find traces of a bygone state of over-population, when the resources of even a tropical soil were taxed, and even the improvident Polynesian trembled for the future.
Add to this the evidences of over-population and imminent famine already adduced, and I think we see some ground of indulgence for the island cannibal.