In artificial selection, natures provides the variation, and humans select those variations that they find useful. Although, humans chose which crop to breed, this is based on natural variations, such as producing more peas in a pod (if the crop were peas).

The process of evolution by natural selection acts upon the **traits** and **characteristics** exhibited by organisms. Those that exhibit traits that increase their chances of survival and reproductive success are “naturally selected” over those that do not.

In the context of their environment, naturally selected organisms are those that have beneficial traits known as *adaptations*. These traits increase the “fitness” or the overall suitability of an organism in its environment.

Organisms that do not exhibit adaptations would therefore be “selected against” by nature, which may cause them to die out. This is because they have less fitness, which means that they are not well-suited to their local environment.

Some of the evidence used by Darwin to support his theory of evolution or change over time are the **fossil record** and the presence of **homologous structures** among related organisms.

The fossil record provided information on organisms that lived in the past. Darwin explained that some of these organisms exhibit similar traits and characteristics. One example of such a similarity is the presence of homologous structures.

Homologous structures are structures that are found in different but related organisms that was derived from a shared common ancestor. The presence of these structures provided evidence that an ancestor had “changed over time” into modern organisms.

Another evidence that Darwin used to support the theory of evolution is the **embryology** of organisms. He explained that some organisms have similar developmental patterns, which may suggest that they have descended from a common ancestor.

Some evidence of evolution can be found in the fossil record; researchers have found many transitional fossils. These show the stages in the evolution of modern species. The geographical distribution of living species also proves this. For example, the species of finches Darwin collected from the Galapagos Islands were all similar, but had certain different features. The finches from different islands were all different from each other and from fiches in mainland South America. This shows that the finches evolved based on their environment. Homologous body structures in certain animals show that four-limbed vertebrates have descended with modifications from common ancestors. For example, dolphins have lungs rather than gills although they live in a water habitat. They are also warm-blooded. Most underwater creatures have gills and are not warm blooded. This shows that dolphins have descended from land animals; only land animals have these characteristics. During early stages of development, embryos grow in similar ways, with common cells and tissues the produce homologous structures. Using this evidence, we can support and prove Darwin’s theory of evolution.