(W) In 1798, Thomas Robert Malthus published an essay, "An Essay on the Principle of Population." Malthus proposed that the current rate of population growth would deplete current resources.
(X) 1809 marked the publication of the first theory of evolution. Jean Baptiste Lamarck proposed that evolution occurred through the inheritance of acquired characters.
(Z) In 2003, Wayne State University School of Medicine's Dr. Morris Goodman conducted studies that revealed a 99.4% genetic similarity between human and chimpanzees. This sparked a debate in the scientific community whether to include chimpanzees in the genus, Homo.
* If Y is part of the choices, it comes after (X).
