Charles Darwin’s findings in South America and the Galapagos islands promted him to think of what has been called the “Greastest Idea of all time”; The theory of evolution. In South America, Darwin found the fossils of a giant sloth, which he was able to trace back to modern, smaller size sloths that were still alive. This was the evidence that put his train of thought in motion. Later, he travelled to the Galapagos islands and made many observations there, as well as collecting samples of different animals, most notably the Galapagos finches. However, Darwin did not fully complete his theory until he returned home. There, he studied his findings and was intruiged by the finches. He noted all the similarities and differences between the finches, such as their different sizes and beaks. Darwin arrived at his theory after studying embryos of different species and noted that they all started out very similar, and that the developmental process was where they began to slowly differentiate. This sparked an idea of a common ancestor. For example, a single species of finch could have journeyed to the Galapagos and, over time, have evolved into many different species. Darwin’s theory was absolutely correct, however, he had no idea how it happened.
What Darwin never knew about was DNA. A species gradually changes over time through random genetic mutations, which can give different characteristics to a member of a species. Should this mutation be beneficial to said member, chances are that they will live long enough to reproduce, and thus pass on the mutation to their offspring. Keeping a specific group of a species isolated long enough, (isolating the gene pool), will broaden the chances of a new species forming, since the two seperated groups will keep different mutations contained within their individual offspring. Given enough time, the single species could easily become two. This is how a single common ancestor could’ve, over many years, become the millions of species that we have on our planet today. In conclusion, DNA was the missing link to Darwin’s theory of evolution, the key to all life on earth.