Evolutionary Theory Timeline By Terika Sep 30, 1795 Hutton proposes his theory of gradualism. Sep 30, 1798 Malthus publishes "Essay on the Principle of Population" Sep 30, 1809 Lamarck publishes his theory of evolution Sep 30, 1830 Lyell publishes Priciples of Geology Sep 30, 1831 Darwin travels around the world on the HMS Beagle Sep 30, 1832 Darwin travels around the world on the HMS Beagle Sep 30, 1833 Darwin travels around the world on the HMS Beagle Sep 30, 1834 Darwin travels around the world on the HMS Beagle Sep 30, 1835 Darwin travels around the world on the HMS Beagle Sep 30, 1836 Darwin travels around the world on the HMS Beagle Sep 30, 1837 Darwin begins his notebooks on the origin of species Sep 30, 1844 Darwin writes his essay on the origin of species Sep 30, 1858 Wallace sends his theory to Darwin Sep 30, 1859 The Origin of Species is published Sep 30, 1865 Mendel publishes inheritance papers