It took British naturalist, biologist and geologist Charles Darwin nearly 20 years to publish his research which confirmed that organisms evolve through a process called natural selection and that the traits passed down generations are the ones which help them adapt to the environment. A result of his findings during the HMS Beagle expedition, the book, On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, published on November 24, 1859, laid the foundation for evolutionary biology. Over 160 years on, here's what you can delve into to learn more about the man and the theory that contributed towards most of our understanding of the life sciences.

Charles Darwin. Pic courtesy/Wikimedia Commons