Image from https://singularityhub.com/2016/09/09/is-evolution-over-synthetic-biology-anticipates-natures-next-steps/#sm.00000r0oxa07d7efiur2gmzbwcv12
Charles Darwin explored the Galapagos Islands in the early 19th century. There he studied the different animals that lived on the islands which inspired the theory of evolution. The theory of evolution explains how complex creatures are descended from more simple organisms, and how all creatures on Earth are related. This theory is often described as “survival of the fittest”, although this is slightly misleading, a more accurate description is “evolution by natural selection”. This theory suggests that random mutations in organisms and natural selection cause organisms to differentiate and eventually become separate species. The organisms best adapted to their environments (who do not meet their end by accident, starvation, or predator) are the ones who live and pass on their genes to their offspring—although genes and DNA had not been discovered in Darwin’s time.
The Galapagos tortoises were inspiration for Darwin's theory of evolution. Image from http://www.bbc.com/earth/story/20150803-how-do-we-know-evolution-is-real
Read more about Darwin and his theory of evolution at the Smithsonian website : https://www.smithsonianmag.com/science-nature/the-evolution-of-charles-darwin-110234034/