Darwin and Wallace were both strongly influenced by the book "An Essay on the Principle of Population" written by

Both Charles Darwin and Alfred Russel Wallace were significantly inspired by Thomas Robert Malthus's book, "An Essay on the Principle of Population." Malthus argued that human populations grow geometrically while food production increases arithmetically, leading to a struggle for survival due to limited resources. This concept provided the foundational groundwork for the theory of natural selection.