Final answer:
Charles Darwin came up with the concept of natural selection after observing the principles of artificial selection used by farmers. He theorized that nature similarly selects for advantageous traits, leading to the evolution of species over time.
Step-by-step explanation:
During his observations and interactions with farmers who practiced artificial selection, Charles Darwin developed the idea of natural selection. Artificial selection involved humans selecting and breeding animals and plants with desirable traits to enhance them for farming, leading to changes over time. Darwin applied this concept to nature, theorizing that in the wild, individuals with beneficial traits that improve their chances of survival and reproduction would pass these traits to their offspring, thus leading to the evolution of species. This understanding was pivotal to his theory of evolution by natural selection.
Natural selection, as opposed to artificial selection, is the mechanism by which individuals with advantageous traits are more likely to survive, reproduce, and pass on their traits to the next generation. Darwin coined the term fitness to describe an organism's ability to survive and reproduce, and the concept of 'survival of the fittest' to describe this natural process that leads to evolutionary change and the development of new species over time.