Theory of Evolution: Charles Darwin and Natural Selection

Theory of Evolution

Evolution includes two major mechanisms:

  • Natural selection
  • Random mutations

Natural selection is the idea that the “most adapted” species survives in an environment.

Then, mutations refer to changes in an organism’s genetic code which could be harmful, neutral or beneficial.

One takeaway to keep in mind is that evolution takes time. You won’t evolve over the span of your life. But it takes millions of years for species to evolve.

Natural selection and survival of the fittest

Human Evolution

The first mechanism that drives evolution is natural selection. There’s a common misconception that natural selection is the survival of the fittest.

It doesn’t necessarily mean that the strongest organism always survives. Instead natural selection is the idea that the “most adapted” species survives in an environment.

For example, flies are small, fast and durable for their size. Also, they reproduce in large numbers and find food nearly anywhere. Because of these traits, they are able to survive and reproduce.

And make no exception that human evolution hasn’t stopped. In flesh and blood, we have been genetically fine-tuned as a product of natural selection. For example, we pass on a wide variety of favorable traits for our offspring.

Changing the genetic code by random mutations


Mutations refer to changes in an organism’s genetic code. In nature, mutations are random. Without mutation, there wouldn’t be any variations to pass to offspring.

Genetic mutations can be beneficial for species. For example, a giraffe that mutates a longer neck can reach more leaves for food. Over time, long-neck giraffes survive to pass on its genes. But shorter giraffes don’t.

On the other hand, genetic mutations can be harmful such as in the case of being exposed to chemicals. Environmental factors like overexposure to UV light or carcinogens can shape mutation rates as well.

Ideally, nature would select only beneficial mutations. But mutations don’t necessarily supply what an organism needs to survive. Overall, the key takeaway is that mutations are random and they operate at a genetic level.

Tropical rainforests are the most diverse ecosystems on the planet

Island Water Rocks Palm Trees Landscape

Without evolution, there would be no biodiversity hotspots like tropical rainforests. This is because life evolved in some of the toughest conditions.

For example, rainforests have an overabundance of water and nutrient deficient soils. Living organisms have adapted to these hostile conditions with evolution doing the work.

Over time, these plants, animals and fungi have developed immunity to harmful bacteria and viruses. This is because whatever doesn’t work just doesn’t survive in such harsh environments.

This is why we find the most resistant chemicals for medicine in tropical rainforests. For example, approximately 1/4 of all prescription medicines are derived from rainforest plants.

Human Evolution Timeline

How did we evolve?

Human Evolution

Leave a Comment