In the 1800s, Charles Darwin went on an expedition around the world. He observed and collected a large number of different plants, animals and fossils. He also studied the geology of the lands he visited. Once Darwin returned, he continued to develop his ideas and discussed his findings with other scientists.
In 1859, Darwin published his theory of evolution by natural selection in a book called On the Origin of the Species.
Darwin’s theory states that:
During the era in which Darwin lived, Christian teachings dominated, leading many to reject his ideas. In this era, many people strongly believed that God created all the animals and plants on Earth. However, some ideas were accepted as ground-breaking in explaining the development of species over time.
Evolution through natural selection is based on the principle that all living things have developed from simpler life forms over a long period. The Earth is approximately 4.5 billion years old, and scientific evidence suggests that life began on Earth over three billion years ago.
As Darwin shared his ideas and collaborated with scientists such as Alfred Russel Wallace, who independently developed a similar theory, the concept of evolution through natural selection became more widely accepted.
The impact of the findings has motivated scientists to find more information to support the theory. But still, many people were reluctant to accept Darwin’s theory of evolution.
Aside from Darwin, other scientists put forward their own theories on how species changed over time.
For example, Jean-Baptiste Lamarck was a French scientist who devised a different theory of evolution in the early 19th century (before Darwinism). Lamarck suggested that when a characteristic is regularly used, it becomes more developed. He also suggested that changes that occur in an organism during its lifespan can be passed down across generations.
However, there is a big problem with Lamarck’s theory. We now know that most changes that occur in an organism’s lifetime are not passed on to its offspring. For example, a bodybuilder will not pass on their added muscle to their offspring.
Today, scientists widely accept Darwin’s theory of evolution by natural selection as the primary explanation for why species change over time.