Charles darwin, who is credited with the discovery of the principal of natural selection in 1838, was born in england in 1809. Darwin was part of an expedition to map the coast of south. America between 1831 and 1834-35 aboard the hms beagle. As the naturalist for the expedition, darwin was in charge of collecting and describing plant and animal specimens encountered on this expedition. During his long journey, after observing incredible plant and animal diversity, as well as fossils, he became interested in the question of how species come about. He was convinced that species came about by slow change. Just how species changed was still a mystery. In 1838, shortly after returning home from his journey, darwin read thomas malthus" essay titled an essay on the principal of population . In this essay malthus, among other things, presents the notion that populations can increase in size exponentially while food supplies remain relatively stable.