The theory of natural selection remains the key to our understanding of the natural world.自然选择的理论仍然是我们理解自然界的关键。Darwin formulated the theory of natural selection.达尔文创立了物竞天择的理论。The theory of natural selection was first propounded by Charles Darwin.物竞天择的理论最初是由查尔斯·达尔文提出的。