Charles Robert Darwin was born on February 12, 1809 in Shrewsbury, England. Darwin's theory of evolution and natural selection support the fact of why there is variation among animal species today. The survival or extinction of each organism is determined by that organism's ability to adapt to its environment. Different variables added to an organism's ecosystem can effect the survival of the organism as well. Whether there is much competition between food and shelter, there is more of a difficulty to survive. Natural selection comes into play when this happens. The females will mate with only the males she feels is the best equipped to survive for generations. She will reproduce with the male and his beneficial genes will be past onto their offspring who will eventually gain these beneficial traits and survive. However the ones without these better traits for living, they will not reproduce, and their genes will not be past down to offspring.