Introduction to Charles Darwin's Theory of Evolution

In 1859, when Charles Darwin published The Origin of Species, people didn’t know anything about the mechanisms of fertilization, genetics or paleontology. They didn’t have any human fossils to study the ancestry of man or a correct time-scale of evolution. After the scientists reviewed and accepted Darwin’s theory of evolution, The Origin of Species became one of the most important biology books. Sir Julian Huxley says that it is a “great book, one that after a century of scientific progress can still be read with profit by professional biologists.”

Darwin’s theory can be described in the following way. All organisms descended from a simpler common ancestor. Those organisms “descent by modification.” This expression means that living organisms acquired mutations or changes that allowed them to adapt and survive in different environments, temperatures or other kinds of selective pressure. In other words, natural selection that acts like a selective pressure favored organisms that developed mutations that allowed them to survive in harsh conditions. As a result, they reproduced and their offspring inherited the traits that helped them survive. Only organisms that inherited those specific traits were able to adapt to different environments.

“The survival of the fittest” is a powerful expression that Darwin used to explain how natural selection favors individuals that inherit different traits to survive and reproduce successfully. Darwin said that “it is not the strongest of the species that survive, nor the most intelligent, but the one most responsive to change"(Darwin). Darwin mentions that the heritable traits are the ones that allow organisms to survive different selective pressures.

Those traits are transferred from generation to generation and are favored by natural selection. In the next post, we will see how scientists started researching what were those heritable traits and how genetics developed from that point. Examples of research from the University of Maryland will be used to explain better technology and scientific research.

Picture source: Evolution