After years of exploration, collection, and observations topped with several decades of critical thinking, Darwin crafted his grand theory of evolution. His theory of the transmutation of life over time became the cornerstone of modern evolutionary synthesis. What did Darwin base his theory of evolution on and what does his theory propose?
A Voyage of Exploration, Collection, and Observation
“After having been driven back twice by heavy southwestern gales, Her Majesty’s ship Beagle, a ten-gun brig, under the command of Captain Robert Fitzroy, R.N., sailed from Devonport on the 27th of December, 1831.”
(From an account by Charles Darwin)
So began a five-year round the world voyage of survey, exploration and collection that while modest in scope, produced repercussions whose importance reverberates to this day.
Aboard the Beagle as the ship’s naturalist was young Charles Darwin. When he sailed away, Darwin was a young university graduate filled with a life-long passion for plants, animals and all things natural and an immense interest in all the sciences, especially geology.
By the time he returned, Darwin was an established naturalist, known for the remarkable specimens he had sent ahead, and he had grown from a mere observer into a probing theorist. By any measure Darwin’s labors were hugely successful but more importantly, the trip gave him a lifetime of experiences to ponder and planted the seeds of a theory he would work on for the rest of his life.
Darwin Begins to Formulate His Theory of Evolution
Darwin was barely off the ship before his next great journey – a journey of the mind – began. For the next several decades Darwin would ponder and question the biological wonders he had seen. He quietly gathered evidence from every possible source and sought out new ideas to support a notion regarding the transmutation of species that was gaining form and clarity in his thinking.
In November 1859, On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life was published. It took but one day for all 1,250 first-printing copies to sell out and the publisher quickly rushed 3,000 more copies to print. As Darwin suspected and feared, the book created instant controversy and misunderstandings that continue to this day.
Theories Within a Theory
Darwin believed that creatures arose from a common ancestor and that species were transmuted over time (or "descent with modification" as it is sometimes known). It has been suggested that Darwin’s theory of evolution is not a single theory but rather a melding of several different but mutually compatible theories. In order for evolutionists to fathom the total process of evolution, they must first understand the workings of each Darwinian subtheory.
- Perpetual change. This is the core on which the other theories rest. It states that the living world is constantly changing and as it does so, organisms undergo transformation across generations throughout time.
- Common descent. The second subtheory states that all forms of life descended from a common ancestor through a branching of lineages. Studies of organismal anatomy, cell structure, and macromolecular structures confirm the idea that life’s history has all the components of a branching evolutionary tree.
- Multiplication of species. The third subtheory states evolutionary processes produce new species by splitting and transforming older ones. While evolutionists generally agree with this idea, there is still much controversy concerning the details of the process.
- Gradualism. The fourth subtheory states that the large differences in anatomical traits that characterize different species originate through the accumulation of many small incremental changes over long periods of time. Evolutionists today concede that while gradual evolution is known to occur, it may not explain the origin and development of all the structural differences between species.
- Natural Selection. The fifth subtheory, Darwin’s most famous, holds that all members of a species vary slightly from each other and thus have different structural, behavioral, and/or physiological traits. Those organisms with variation in traits that permit them to best exploit their environment will preferentially survive and pass these beneficial traits on to future generations. Over long periods of time, the accumulation of such favorable variations produces new organismal characteristics and eventually new species. This proposition has been popularly termed “survival of the fittest” but might be more accurately described as “survival of the best adapted and most reproductively fit.”
Charles Darwin died on April 19, 1882 and is buried in Westminster Abbey. Darwin’s ideas and theories stand among the greatest intellectual achievements of all time. They continue to influence scientific, religious, and social thought with ramifications that extend to the daily existence of each one of us.
"Doing what little one can to increase the general stock of knowlege is as respectable an object of life as one can in any likelihood pursue."
(Charles Darwin)
Dennis Holley - Looking back, it's clear that I have been a science nerd my entire life. A simple, almost toy-quality microscope my poor parents scraped ...
