Atengah wantah panglalah saking An Essay on the Principle of Population (1798) olih Thomas Robert Malthus, Darwin nyatet indik  populasi sayan nicap pacang ngawinang "mautsaha mangda setata langgeng" raris variasi sané becik pacang langgeng raris sané tiosan pacang padem.
Partly influenced by An Essay on the Principle of Population (1798) by Thomas Robert Malthus, Darwin noted that population growth would lead to a "struggle for existence" in which favourable variations prevailed as others perished.