Charles Darwin was a young, British naturalist when he came forth with the renowned theory of biological evolution through natural selection. He defined evolution as a process where species change over time, and they produce new species who all share the same ancestor.
The mechanism that Charles Darwin proposed happens during evolution was natural selection. This basically meant that since resources are limited in nature, creatures with heritable characteristics that favor reproduction and survival always tend to leave behind more offspring compared to their counterparts, causing the trait to increase in occurrence throughout generations.
Let us take a closer look at his theory of evolution. The basic idea behind Darwin’s biological evolution is that species of organisms and populations will change over time.
As I mentioned in the preceding section, Darwin wrote and published a controversial and influential book in the 1850s. This book was titled “On the Origin of Species.” In the book, Darwin proposed that organisms and species evolve (or as he stated it, “they undergo ancestry with modification”) and that all living creatures can trace their ancestry to the same ancestor.
Darwin also proposed a specific mechanism that aids in evolution, i.e. natural selection.
In this section of the content, we will take a closer look at how Darwin’s visit to Galapagos aided in these ideas. Let us start with his voyage of the Beagle.
Through his seminal book, Darwin set forward his ideas regarding natural selection and evolution. He largely based these ideas on his direct observations through his travels around the world.
From the year 1831 to 1836, he was a member of a survey expedition crew on board the ship HMS Beagle. This ship’s stops included the southern tip of Africa, Australia, and South America. During each expedition stop, Darwin had the chance to catalog and study the local animals and plants.
Throughout the course of his voyage, Darwin started to see an intriguing pattern in the features and distribution of living organisms. He notes that one of the most imperative patterns he noticed in regards to organism distribution was through studying his observations at the Galapagos Island situated off the coast of Ecuador.
Darwin realized that neighboring islands in the Galapagos featured similar, yet non-identical types of finches. In addition to that, he noted that every finch species was best suited for its role and environment.
For example, he realized that bird species that fed on large seeds boasted big, sturdy beaks, whereas those that fed on small insects had thin, piercing beaks. Furthermore, he noted that finches and other creatures living on the Galapagos Islands boasted similar characteristics, but they were completely different from those found elsewhere in the world.
The Galapagos Islands were all recently formed and volcanic in nature, Darwin thought. Which meant that the species dwelling on the island must
have migrated there from some other place. Those closest that resembled the animals on Galapagos Island were ones living on the mainland. But still, they were not similar in traits. Why? This was the single question that plagued Darwin the most.
Darwin did not figure out all this during his first trip. As a matter of fact, he did not even comprehend that all finches were related until he presented his specimens to another skilled bird biologist 8 years later. This new colleague and friend was Sir Joseph Hooker.
Progressively, however, Darwin came up with the idea that he could explain the pattern of correlated, yet different finches.
According to Darwin’s theory, the pattern would only make sense if the islands were populated by birds from Ecuador’s mainland long ago. He stated that on each island, the finches may have slowly adapted to the local environmental conditions. But this must have happened over lots of generations and a long period of time. This selection process may have led to the creation of one or all the distinct species on the island.
During his HMS Beagle voyage and years after, Charles Darwin refined and developed a set of ideas that can explain all the patterns he witnessed during his voyage. In his book “On the Origin of Species”, he outlines his two key ideas; natural selection and evolution.