What is the theory of evolution by natural selection?

The theory of evolution by natural selection is a scientific explanation for how species evolve over time through genetic changes.

The theory of evolution by natural selection, often associated with Charles Darwin, is a fundamental concept in biology. It proposes that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce.

The process begins with genetic variation. Individuals within a species have slight differences in their genetic makeup, which are often the result of mutations. These genetic differences can lead to variations in traits, such as size, colour, or resistance to certain diseases.

Natural selection comes into play when these traits affect an individual's survival or reproductive success. For example, if a particular trait helps an individual survive longer or reproduce more, that trait is more likely to be passed on to the next generation. Over time, these advantageous traits become more common within the population, leading to evolutionary change.

This process is not guided or planned, but rather, it is the result of individual survival and reproduction in a particular environment. It's important to note that natural selection does not lead to 'perfect' organisms, but rather to organisms that are 'fit' for their specific environment.

The theory of evolution by natural selection is supported by a wide range of evidence, from the fossil record to genetic studies. It helps us understand the diversity of life on Earth, the relationships between different species, and how organisms adapt to their environments.