Charles Darwin (1809–1882) English naturalist, geologist and biologist published his work in 1859. It is considered to be the foundation of evolutionary biology. He introduced the theory that populations evolve over the course of generations through a process of natural selection. Darwin included evidence that he had collected during an expedition, his subsequent findings from research, correspondence, and experimentation. His ideas conflicted with the beliefs that species were unchanging parts of a designed hierarchy and that humans were unique, unrelated to other animals.
The summary of Darwin’s theory is that every species is fertile enough that if all offspring survived to reproduce, the population would grow. Despite periodic fluctuations, populations remain roughly the same size. Resources such as food are limited and are relatively stable over time. A struggle for survival ensues. Individuals in a population vary significantly from one another. Much of this variation is heritable. Individuals less suited to the environment are less likely to survive and less likely to reproduce; individuals more suited to the environment are more likely to survive and more likely to reproduce and leave their heritable traits to future generations, which produces the process of natural selection. This process results in populations changing to adapt to their environments, and ultimately, these variations accumulate over time to form new species.
Image photo: Charles Darwin by unknown artist.
