Traditional religious literature promotes the theory of special creation, which suggests that all living organisms were created in their current forms and that Earth is around 4,000 years old.

Charles Darwin challenged these ideas in the 19th century. He embarked on a voyage on H.M.S. Beagle and observed that existing life forms share similarities with those that existed millions of years ago. Many extinct life forms have left their mark on the living ones.

Darwin proposed the theory of gradual evolution, where variations in characteristics naturally occur within populations. Those with advantageous traits for surviving in their environment have a higher chance of reproducing.

Fitness, according to Darwin, primarily relates to reproductive success. Individuals better adapted to their environment leave more offspring, resulting in their traits being passed on.

Natural selection, as coined by Darwin, acts as the mechanism of evolution. It leads to the survival of individuals with beneficial traits.

Alfred Wallace (who worked in the Malay Archipelago), a naturalist, independently reached similar conclusions about evolution.

Over time, new types of organisms have emerged, yet they share common ancestors at different points in Earth’s history (epochs, periods, and eras).

Earth’s geological history aligns with its biological history, and it is now understood to be billions of years old rather than just thousands of years.