Adam Sedgwick, British geologist, Anglican priest and doctoral advisor to Charles Darwin (born 1785)

Adam Sedgwick FRS was a British geologist and Anglican priest, one of the founders of modern geology. He proposed the Cambrian and Devonian period of the geological timescale. Based on work which he did on Welsh rock strata, he proposed the Cambrian period in 1835, in a joint publication in which Roderick Murchison also proposed the Silurian period. Later in 1840, to resolve what later became known as the Great Devonian Controversy about rocks near the boundary between the Silurian and Carboniferous periods, he and Murchison proposed the Devonian period.

Charles Robert Darwin was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended from a common ancestor is now generally accepted and considered a fundamental scientific concept. In a joint presentation with Alfred Russel Wallace, he introduced his scientific theory that this branching pattern of evolution resulted from a process he called natural selection, in which the struggle for existence has a similar effect to the artificial selection involved in selective breeding. Darwin has been described as one of the most influential figures in human history and was honoured by burial in Westminster Abbey.

January 27 is the 27th day of the year in the Gregorian calendar; 338 days remain until the end of the year.