the theory of natural selection (survival of the fittest) states that

In the beginning of the last century, scientists began to understand genetics and how offspring inherited traits from their parents. Over time, the characteristics of the population as a whole can change, sometimes even resulting in the formation of a new species. These adaptations become more common in the population because of this higher reproductive success. Under natural selection, some individuals in a population have adaptations that allow them to survive and reproduce more than other individuals. These modifications were the key to the evolution of new species, and Darwin proposed natural selection or 'survival of the fittest' as the mechanism by which that change occurs. Over time, these populations accumulated modifications, or adaptations, that allowed them and their offspring to survive better in their new environments. As populations of species moved into new habitats and new parts of the world, they faced different environmental conditions.

He postulated that all species have a common ancestor from which they are descended. In this book, Darwin laid out a strong argument for evolution, or 'descent with modification' as he called it. Evolution was first explored in its modern form in Charles Darwin 's 1859 book, On the Origin of Species by Means of Natural Selection.

Theories in Evolution & Population GeneticsĮvolution, the science of how populations of living organisms change over time in response to their environment, is the central unifying theme in biology today. Monarch Watch : Biology : Theories in Evolution & Population Genetics

The theory of natural selection (survival of the fittest) states that