1660Nicholas Steno proposed that fossils once belonged to living creatures. He also claimed that fossils are the key evidence for how life evolved on Earth over the past four billion years^[4]

1758 Carolus Linnaeus (Carl von Linne) introduced the idea of identifying, naming, describing and classifying organisms (species). His hierarchical classification is based on the fact that species was the smallest unit, and each species (taxon) is under a higher category^[4].

In the late 18th century, scientists George Leclerc and Comte de Buffon proposed that species could change. This idea was a major break since it challenged the earlier belief that species could not change because they were already perfect, as a perfect creator created them. Buffon provided some evidence of the said changes and modifications. He also stated that various factors, including migration, geographical isolation, influences of the environment, overpopulation, and struggle for existence, could influence that change. Unfortunately, Buffon later claimed that he believed in special creation and debunked his idea of the modifications of species.

1790s Two scientists named Abraham Werner and George Cuvier proposed the theory of Catastrophism. This theory states that the planet Earth and the geological events formed rapidly and suddenly due to a great catastrophe. This idea became widely accepted because it relates to biblical events like Noah’s flood. However, James Hutton challenged the theory of Catastrophism. He argued that gradual and slow changes transformed the Earth. These changes may be tiny, but with enough time, they could produce great changes^[5].

1798 Thomas Malthus stated that human populations could double every 25 years. After that, the population would gradually exceed the food supply, leading to starvation and war. Eventually, such events will reduce the population^[5].

In the early 19th century Erasmus Darwin (Charles Darwin’s grandfather) suggested the possibility of a common ancestor based on the changes undergone by organisms during development and the presence of vestigial structures. While he proposed that species do change over time, he did not provide any mechanism to explain his idea.

Lamarck’s fame rose when he introduced the idea of the inheritance of acquired characteristics to explain the length of the giraffe’s neck. According to that view, the long necks of giraffes were acquired from their ancestors (who previously had shorter necks), who continually stretched their necks to reach food in high trees. This continuous use of stretching the necks resulted in their development of longer necks, which was somehow passed on to their offspring^[4].

• [1] – All kinds of organisms adapt to their environment.
• [2] – All organisms have variable traits.
• [3] – Organisms tend to over-reproduce (this idea was based on Thomas Malthus’s study of how populations tended to grow geometrically until there was a limit in their population).
• [4] – The idea of natural selection, which is more commonly referred to as “survival of the fittest”.

The idea of natural selection states that some organisms will survive and reproduce better than others. However, natural selection only deals with the reproductive success of the organisms, not only their relative strength or speed.

Charles Darwin made collaboration with Alfred Russel Wallace, who previously was the first to define the role of natural selection in species formation. Charles Darwin eventually published his renowned and highly recognized book On the Origin of Species using Natural Selection^[4].

To be correct, it is important to note that Darwin and Wallace developed the theory of natural selection.

Although Charles Darwin and Alfred Russel Wallace’s theory of natural selection displaced Lamarck’s previous theory, some efforts were still made to revive it and continued^[4].