Meet the Guide Editor
Natural Selection Contributors

Evolution by Natural Selection

Darwin's finches: beak variations

In 1859, Charles Darwin published his most famous work, On the Origin of Species. In it, he introduced a theory to explain how evolution occurs: adaptation by natural selection. Since then, especially after additional advances of scientific understanding in the 1930s and 1940s, natural selection has gone on to become the centerpiece of modern evolutionary theory and the foundational basis of all modern biology.

So what is natural selection? To understand how it works, we must first understand evolution. The basic concept is very simple: evolution is any change in a population of living things over time. The small changes of microevolution are easy to see, for example northern England peppered moths which started out light-colored on trees with light bark, but became dark in areas of trees covered with soot. The larger changes of macroevolution, like speciation, simply extrapolate as very long series of small changes over much longer timeframes.

Natural selection explains how and why these changes occur. In any population in a particular environment at a given time, some individuals will be better adapted to the environment than others. According to natural selection, these individuals will be more successful at passing on their genes to the next generation. Other individuals tend to die out before reproducing. After a number of generations, most individuals will have the successful genes.

Of course, then the environment changes, which may cause the previously successful genes to stop being so successful - there is no absolute "best" in evolution because "best" depends on whatever the environment is at the time. Also, new variations continually arise in the population due to mutation - which in turn makes some individuals better adapted to the new environment than others. Which in turn leads to more natural selection.

Those are the barebones basics, anyway. For more details, read on through the articles below.

Latest Articles on Natural Selection
Animal Biochemical Behavior and Natural Selection

Natural selection and animal biochemical behavior shows how animals adapt to the stresses of their environment in ways which help them maximize their energy and resources. It is a classic...

Examples of Natural Selection

Natural selection is Charles Darwin's big idea, and the process by which organisms adapt to their environment. Over time the evidence has stacked up to support Darwin's work...

The Hardy-Weinberg Equilibrium Theorem

Assume an infinitely large population with two alleles, no natural selection and random mating. The Hardy-Weinberg equilibrium is what you end up with....

Genetics and Natural Selection

Genetics - the theory which explains how inherited characteristics are passed from one generation to the next, and natural selection, which allows fitter individuals to survive and...

Most Popular Articles on Natural Selection
  •  
    Genetics and Natural Selection

    Genetics - the theory which explains how inherited characteristics are passed from one generation to the next, and natural selection, which allows fitter individuals to survive and breed more often than...

  •  
    Examples of Natural Selection

    Natural selection is Charles Darwin's big idea, and the process by which organisms adapt to their environment. Over time the evidence has stacked up to support Darwin's work and there are now many...

  •  
    Animal Biochemical Behavior and Natural Selection

    Natural selection and animal biochemical behavior shows how animals adapt to the stresses of their environment in ways which help them maximize their energy and resources. It is a classic example of evolution...

  •  
    The Hardy-Weinberg Equilibrium Theorem

    Assume an infinitely large population with two alleles, no natural selection and random mating. The Hardy-Weinberg equilibrium is what you end up with....

  •  
    Four Common Misunderstandings About Evolution

    Evolution is a commonly accepted fact for many people, whether or not they are religious. There are also many people who do not accept the theory. But some arguments against evolution are actually based...

More About Natural Selection
Who Chooses What? How Does Evolution Occur?

The understanding of traits being retained or lost in populations in evolution is important, but what are the mechanisms that describe how traits stay or leave?...

The Difference Between Genotypes and Phenotypes

Many people are unfamiliar with genotypes and phenotypes, let alone the difference between genotypes and phenotypes. Learn about the major differences to better understand how they...