A History of Evolutionary Theory

It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change.
~Charles Darwin

Well, here we go. Evolution. What is it and how did we get to the evolutionary theory we have today.  Is it  a theory? Or just a fact of nature? So let’s try to answer those and take a small look at the history of evolutionary theory.

A Brief History of “Pre – Darwin” Evolutionary Theory

Theory and study on evolution existed long before Darwin’s groundbreaking work, dating all the way back to ancient Greece. The first great philosopher we know to have proposed an evolutionary theory similar to the one we have today was Anaximander(610 – 546 B.C.)  of the island state, Ionia. Scientists and philosophers operated differently in Ionia than in mainland Greece. This is where modern science was born. Ionians placed a great emphasis on study, experimentation, and basically created the forerunner to the scientific method.  So,  Anaximander took  a different approach than most to evolution. He was the first to propose life originating in the water. Though it gets a little crazy after that. His emphasis for this theory was the fragile, extended state of human infancy. He felt humans could not survive the primeval world in our current state. We had to come from something else.

His something else was a fish or fish like animal. He believed we existed inside this fish until we were ready to survive the environment. Then we “burst forth” from the fish ready to face the world. Eventually, over time, we lost our scales and adapted to procreate on land. Yes, it’s crazy. But it was very much a “theory of evolution”. He was not alone. There was a growing consensus in some circles that humans had to have come from something else. Been something else before they were fully human. Most often centered around some sort of trek from water to land.  The thought that life began in the ocean and moved on land is very much a part of evolutionary theory today. Following Anaximander was the great Greek philosopher, Plato. Plato put forth the theory of Essentialism.  This theory would guide thoughts on evolution for centuries to come. Plato believed that all species we see on Earth come from a small group of predetermined sources or “essences”. He believed that all animals appeared first just as they are today and never change. All species share similair traits and processes that never change or leave the group. Basically, everything was made this way and it does not change on its own.

This was really the beginning of “intelligent design”. The thought that a creator put everything here just the way it is. Plato’s most famous student, Aristotle brought Plato’s works closer to the science we know today. Even though his work is full of the myth that dominated Greek thought, he made surprisingly accurate assumptions in his work. He described natural progression as a “ladder” or “chain” with weaker and stronger animals. The stronger, more fit animals  assuming higher positions. He was close but he just didn’t have the knowledge we have today. At the end of the day,  he still valued essentialism and the products of the gods.

In China, around the same time, evolutionary theory was also being pondered. Zhuangzi of Meng was also deep in thought on where everything comes from. Zhuangzi was a devout Taoist and used much of this philosophy in his studies. Though he didn’t provide much science to back it up, he proposed that living things “adapt” to their surroundings over time. They transform to meet the new conditions put around them. He believed this applied to human beings as well since we are a part of nature. This is  a basic tenant of Taoism, that nature is in a constant state of transformation. No matter the thought process he used to arrive at his decision, he was closer to the truth than anyone had yet come. Some in the Western world would mirror his work.  In ancient Rome, a similar theory of  a “transformational” aspect to nature began taking hold. St. Augustine of Hippo , a Christian firebrand and “founding father” of modern Christianity, also put forth a version of evolution a few centuries later. He believed GOD created all things, but not to stay as they are. He very much mirrored the thoughts of Zhuangzi on the “ascension” of  species.

When Rome fell,  the Middle East took up their scientific pursuits. Muslim biologist and philosopher, Al-Jāḥith contributed ideas to evolutionary thought that would influence many researchers who followed him. He was one of the first people to speculate in detail on the influence the environment has on  an animal’s growth and chances for survival. He was also one of the first to describe and lay out a complex “food chain” structure in nature. It was distinct from Aristotle’s earlier work in that it promoted a more natural means to the “transformation” of life, and  a natural process in determining his food chain.   The Arab world was  a bridge to ancient Greek thought and philosophy  for the Western world. While Europe toiled in the “Dark Ages”, the Middle East became a scientific “mecca”, if you’ll pardon the pun. No? O.K., I’ll punish myself. Moving on. Eventually these philosophies were introduced to the huddled masses in the West, and Christian thought on the subject of nature.

Most Christian philosophers immediately connected to Plato’s ideas of “essentialism”, that all has existed as it was. Working with these ideals, they developed a “great chain of being”.

From Wikipedia:

The chain starts from God and progresses downward to angels, demons (fallen/renegade angels), stars, moon, kings, princes, nobles, men, wild animals, domesticated animals, trees, other plants, precious stones, precious metals, and other minerals.

A place for everything, and everything in it’s place. Each section of the “chain” is also divided into smaller subsections, detailing their position in the “natural order”. Again, another theory for intelligent design and similar to models put forth by Ancient Greek philosophers.  This didn’t keep some Christian philosophers from thinking “outside the chain”….. No? Nothing? *sigh* Thomas Aquinas, a highly influential philosopher and theologian, felt there was a more natural process behind the development of life n Earth. He saw no reason why the universe couldn’t have “evolved” over time after being created. Many early Greek philosophers  had similar ideas, but thought it showed there was no governing presence over the universe. Thomas referred to it as “divine art”, wipe his hands clean, and declared “case closed”. Up to this point we have seen some examples of theories mirroring aspects of present day evolutionary science. Still, almost all theories were anchored in some way to essentialism, and a spiritual nature to the creation of life.

Then the Renaissance hit, and launched one of the greatest scientific revolutions in human history. It is in the 17th century that the term evolution first appears in the English lexicon. It refers to an orderly series of changes or sequence of events. But also in the sense that the outcome was “predetermined”, or the eventual outcome of the process was already known. It all lends to the machine like way many Renaissance thinkers viewed the universe. Processes that are undertaken for  a reason already known to the “machine”. Theories on the makeup of atoms described tiny pieces inside called “monads” , which constantly move and change, guiding everything we see forward. Most theory still had a root in a spiritual aspect but had moved further into the realm of natural processes.

As the Renaissance turned into the Enlightenment in the 18th century, the science of evolution really began to resemble the science we know today. German philosopher Arthur Schopenhauer contributed ground breaking work on hereditary traits, and  John Mitchell, a colonial American doctor and botanist, published a study on racial structures entitled,  An Essay upon the Causes of the Different Colours of People in Different Climates. He theorized that the first of mankind were “dark” in complexion like Native Americans, and the varying races formed as mankind spread to different climates. A theory that should sound familiar to people today.

French naturalist G.L.L. Buffon was one of the first to dispute whether every animal we see is a distinct species or just variations of a common species. He theorized that lions, tigers, leopards, and even house cats all shared a common ancestor somewhere in the past. He speculated that of the 200 known species of mammals at the time, there may be as few as 38 “original forms”. Buffon’s science was still incomplete and, when dealing with the origins of life, he subscribed to the theory of spontaneous generation. A theory that animate matter simply springs up from inanimate matter all the time as opposed to some sort of biological reproduction. The theory was first proposed in Ancient Greece and lasted on into the 19th century before being completely tossed aside. In the late 18th century James Burnett(Lord Monboddo), published a series of highly influential writings including a theory involving man descending from primates, and species “evolving” over time to meet changing environments. Burnett was also a deist though and, though he believed man came from apes, he couldn’t get from ape to man without some sort of divine influence. The Enlightenment set the ground work for the transformation of evolution into a real science. Though many great Enlightenment thinkers still held spiritual beliefs tied to evolution, many struggled to hold onto them in the face of coming scientific revelations. By the dawn of the 19th century, essentialism, spontaneous generation, and all other theories involving an unnatural process were slowly fading away.

In 1796 Charles Darwin’s grandfather, Erasmus Darwin(awesome name), published Zoönomia. In it he proposes that all life began as simple organisms in the mud and gradually changed into all the life we see today. This was another key contribution to evolutionary thought. The Force was strong in the Darwin family. Later that same year French naturalist Georges Cuvier published a paper concerning the long running argument on extinction. He was able to determine that mammoths and mastodons  were distinct species, separate from modern day elephants. This proved once and for all that the extinction of species was possible and basically nailed the coffin lid shut on several prominent evolutionary theories dealing with spontaneous generation and essentialism. Study of fossil records took off in the early 19th century and contributed greatly to new theories of evolution. Dozens of articles published by prominent geologists throughout the early and mid 19th century brought about a greater understanding of the natural processes that have shaped our Earth, and continue to shape it to this day.  Cataloged differences in stratum from various time periods, and noted differences in fossil records in each period, proved there were long term processes at work in the Earth. This line of thought influenced evolutionary theorists. In particular, Charles Darwin.

The Voyage of the HMS Beagle

Charles Darwin was not born to change the world. He was born to be a doctor. Or at least that is what his father had envisioned for him. But Charles was not much of a studier in school. A trait found in many brilliant people through out history. He had no interest in becoming a physician. When his studies slipped, his father sent him off to a fine Christian college to become a priest. He showed even less interest in that. Apparently more  content to spend his days riding and shooting. It was during this time that he first ventured into the field that would dominate the rest of his life. A friend of Darwin got him interested in beetle collecting and the wider world of entomology , the study of insects. He spent the next few years at Cambridge studying any book  on natural philosophy, geology, and natural science he could find. At this point Darwin decided he wanted to become a dedicated naturalist. Or, at the very least, a geologist who kinda gives  a shit.

Eventually his studies got him  noticed and won him a seat on a boat, the HMS Beagle captained by Robert FitzRoy, embarking on a major study of plant and animal life  on the coastline of South America. Darwin’s father, of course, was completely against the planned 2 year expedition. With convincing  from family, Darwin’s father finally consented to his participation in the voyage. The journey that would change not just Darwin’s life, but the entire scientific world, was about to begin. On December 27, 1831  the Beagle left port from Plymouth Sound in southern England, bound for the east coast of South America. This would be the Beagle’s second trip to the continent. The first ended abruptly when the original captain had committed suicide. FitzRoy wanted very much to return and finish the original survey with a prominent naturalist. He was very impressed by Darwin’s early works and asked him to come along.

Darwin was ready but he was still very much a student. He spent much of the trip making various notes on geological conditions. He had developed a great interest in geology during his last years at university and felt it was the one thing he was most prepared for. It would be a very educational voyage. Accompanying them on the trip was ship surgeon  Robert McCormick,  a glory hound. McCormick had plans to become  a great explorer and was going to use this trip as his launch pad to international fame and fortune. Most “ship surgeons” acted as the on board naturalist as well. Btu with Darwin along for the trip, McCormick was pretty much ignored by FitzRoy. Something he wold not let either Fitzroy or Darwin forget. Darwin would later say of his traveling companion, “My friend [McCormick] is an ass, but we jog on very amicably”.

The first stop of their voyage was the island of Santiago, part of the Cape Verde island chain off the west coast of Northern Africa. Here Darwin made notes on a line of volcanic rock high above the sea containing seashells, reinforcing current geological theory of the earth rising and falling over countless millenia. The results greatly pleased FitzRoy and Darwin began to develop a great appreciation for the seemingly mundane task of fossil research.Darwin also noted and took samples of strange breeds of octopus who seem to change their color whenever the need arose. A fact already known by many naturalists but further study was greatly appreciated.   For 23 days the group stayed and explored the islands. On one particular day FitzRoy and Darwin took a small boat to an island to observe bird behavior. One note they made said they found the birds had absolutely no fear of humans. You could get close enough to grab one. McCormick was left to circle the island and wait for their return. He was not pleased.

From Cape Verde the Beagle sailed straight for Brazil. Darwin absolutely fell in love with the place. Never before has he seen such beauty and diversity in animal species. He hardly ever returned to the boat, only showing up at agreed upon times to head to a harbor and mail away their findings. He spent many days walking through the lush tropical forests not even taking notes, just enjoying the splendor all around him. But Darwin’s image of paradise was soon tainted by an ages old evil; slavery. Darwin found it hard to work with locals using slaves, often times refusing to even be a part of any expedition using them. At one point Fitzroy brings Darwin to a slaveowner to try and defend the practice of slavery. he tells the slaveowner to ask this slaves if they would rather be free. They all say no. Darwin, of course, could not accept that answer. They had a figurative gun to their head. What answer did they expect?

FitzRoy began to grow annoyed with Darwin’s constant complaints about the use of slave labor and, in a rage, banned Darwin from his company. However, once tempers cooled, FitzRoy returned apologetically to Darwin and the two resumed their partnership. For they were now very much partners. MCormick had become an afterthought by now. Darwin, as a guest of the captain, received the same level of hospitality and service the captain received and this further angered McCormick. But the guy was  a dick and a fame whore so who cares, right? It was now April in the year 1832. day by day McCormick saw his chances of becoming super famous dwindling. With no prospects in the immediate future, and Fitzroy once again fawning all over Darwin, McCormick quit the expedition and returned to England. Years later he would achieve some fame with expeditions of his own but not the immortality he was looking for. That belonged to Darwin.

For almost 3 years the Beagle sailed up and down the coast of South America, stopping wherever they felt they could make suitable finds. Darwin began charting and cataloging some of the most detailed fossil studies of the time.  Darwin was looking to challenge the existing theory that there were no shared ancestors between species and that life mysteriously appears in certain areas, and then dies off when the environment changes. Everything Darwin had seen during his “forest walks” in Brazil challenged that notion. He was beginning to believe species didn’t just die out when circumstances changed. he believed certain, “industrious species” changed with the environment. Adapted to meet the new demands placed on them. And if they didn’t, then they died. Many researchers back in England were pulling the same idea out of the works he had mailed home.

The fossil records were showing some uniformity between extinct species and those existing today. The same work that would lead later paleontologists to link dinosaurs and birds. Darwin and FitzRoy were both amazed at the amount of fossils they were finding which matched recovered fossils in Europe. The first theory of a “super continent”, a time when all the great landmasses were pushed together, was still decades away but the proof was beginning to pile up. Even without the later revelations on the Galapagos Islands, Darwin’s fossil studies were putting together a very compelling case for the evolutionary theory he would later propose. One man in particular would help Darwin immeasurably.

Alfred Russel Wallace was a true naturalist. Unlike Darwin he already approached  his studies with the idea that species evolve or “transmutate’ over time. Like Darwin he explored the rich diversity of life in South America and the surrounding islands. Wallace’s chief contribution was his study of the geographical spacing of “like species”. It was long the belief that species do not change. They appear in certain areas and die there. In the same are we find the “like species” that “replace” them. Wallace’s work would greatly challenge that theory and help complete Darwin’s masterwork. In the jungles of Brazil Wallace found similar species of monkey separated by immense tracks of land. Most often divided by the Amazon river. And so he wondered just how much  study on species separation deals with  differences over such vast distances. Turned out, not much.

We will return to Wallace and his ground breaking work  but, for now, back to Darwin.  September 0f 1835, the Beagle reaches the Galapagos Islands. Here is where Darwin will make some of his greatest revelations and hit on the epiphany that leads to the Origin of Species. For much of the trip Darwin had been mostly making fossil and geological notes and records. Not that he didn’t like it. Part of his excitement for reaching Galapagos was the possibility of seeing active volcanoes. His hopes where quickly dashed when he realized geological activity was minimal. At this point Darwin began to make real comparative studies of species. His first revelation, relatively early on, came when he noticed a mockingbird perched on a nearby bush. He first noticed how incredibly similar it was to other species he had encountered on  previous islands. He was beginning to see the formula that had intrigued Alfred Wallace.

While studying the majestic tortoises of Galapagos  he was told by a local that each turtle could be identified by it’s shell. Each island had a different shell design. This too fascinated him. These tortoises were obviously the same species yet each area showcased a new variety. Darwin, however, showed a very unscientific indifference to the various forms of mockingbird he found. He didn’t even  bother to label what island he had found them on. Later on he would discover that these “mockingbirds” were rare breeds of finches only found on the islands. This revelation would weigh heavily on his evolutionary theory. At the moment Darwin believed the wide variety on the islands was detrimental to the long term survival of those species. He was still blinded by long held beliefs in transmutation and felt that the species were too spread out to invoke any change they may need.

After Galapagos the Beagle headed for Australia. Her Darwin saw things he never thought he would ever see.  When he encountered his first marsupial, with their front pouches and  odd bone structures, he felt there were 2 “creators” at work on this one species. Which he surely must have believed when he saw his first platypus. His first noticed how soft their bill was compared to the preserved species he had see in museums. Europeans scoffed at the idea that a mammal laid eggs but Darwin saw the proof with is own eyes. It was around this time that Darwin turned from geology and began focusing more on biology. After Australia, Darwin longed to return home. Their 2 year expedition had extended to 5 years and Darwin was tired. After one last stop in Brazil, the Beagle headed for England.

In October of 1836  Darwin set foot on English soil again. He was already a huge celebrity back home. The notes he had routinely mailed back home captivated the scientific community. Everyone was interested to read his eventual publication of what he had learned. After selling off his diary and related notes for publication he began work on the tome that would define his whole life.

The Origin of Species

Darwin immediately retreated to his home to begin experimentation. He kept his notes close to this side and actively sought to prove or disprove everything written within. The work to prepare publication of his theory consumed most of his time. It was the discoveries he made back home, with the tools to properly experiment, that really shaped Darwin’s attitude going into the writing of  On The Origin of Species. Instrumental to his work was his correspondence with our old friend Alfred Wallace. Wallace was already knee deep in theory of what he called “natural selection“. While Darwin was in the middle of writing his historic tome, he received several papers written and published by Wallace on this new theory.  He saw the “missing link” to his own theory of evolution.
Darwin encouraged Wallace’s theorizing and felt they were onto something. Something huge. It wasn’t transmutation or some sort of random process that drove evolution. It was the ordered, beautiful process of natural selection that was creating the diversity Darwin and Wallace had witnessed in South America. It was the only answer for why Darwin was finding similar yet different species so far apart. When the species encountered a new environment it HAD to adapt or die. Once and for all they had the absolute proof that environment and hereditary  genes play the dominant role in evolution. This line of thought would expand in later years to mutations and the “corruption” of gene sequences. Adaptation is  a mutation. It is these mutations that have propelled life forward  for millions of years.

Darwin noted that one particular finch he found on Galapagos looked almost exactly like one he had caught in Brazil except this one had a very different beak, made to dig deep into the bark of the trees on the islands for grubs and nuts. And the curious case of the platypus. An obvious water mammal that had adapted to lay eggs to possibly ensure a greater number of offspring or it could be a leftover evolutionary function from it’s past generations. Study on the platypus is actually still very much ongoing. A strange but fascinating animal. Darwin and Wallace knew they had the evidence necessary to go forward with some of the most groundbreaking work ever published. Not since Galileo turned his telescope to the sky had the scientific world seen such revolutionary change.

On November 24, 1859  one of the greatest pieces of scientific literature ever written was published for the masses. And the masses ate it up. But not everyone as satisfied. Many, including Wallace, were expecting  a deeper discussion of human evolution. Darwin only casually touched on the subject in the first publication.  Many of Darwin’s peers were initially skeptical of the book but, in time, came around. Darwin’s painstaking record keeping and absolute commitment to the scientific process left little room for people who wished to question his theories. Natural selection quickly became the new scientific buzzword, followed later by the term Darwinism.

Many researchers, with Darwin’s book in hand, took to the field to test the ins and outs of Darwin and Wallace’s new theory. Now knowing what to look for and how to look for it,  new discoveries backing up Darwin’s work were found every other month. Suck as flowers that evolved to attract particular breeds of moth to ensure cross pollination. Darwin still worked to tweak his theory and make it more whole all the way up to his death in 1882. For decades Darwin’s theory faced criticism. And not just from religious groups. When later researchers began diving deep into the evolutionary history of man, the thought they we “descended from monkeys” put off more than a few legitimate naturalists. But, as with Darwin’s early theories, the evidence just kept piling up. But one of the greatest boosts to Darwin’s theory came from the process of “artificial selection”. Artificial selection is all around us.

Your pets are a product of artificial selection. The dairy cows you see today did not exist thousands of years ago.  The large utters they carry have grown in size over time under human guidance. Most of the vegetables you eat have been cross pollinated and cross bred so many times that they literally cannot reproduce on their own without human help. And we made all of this.  Humans. In only the last few thousand years. Looking at this, it is not hard to imagine the grand changes nature can produce over the millenia. As Carl Sagan said, “Evolution is not theory, it is solid fact.” You only need visit a farm to see it for yourself.

The advancement of gene study has further cemented Darwin’s legacy as we see exactly the predictions he and Wallace made concerning hereditary traits and the changes made in a species. The traits that matter most are carried further generation after generation and it is environmental influences and mutations that eventually produce a new breed adapted to survive the situation it is in. Many times the change doesn’t take or the species merely lacks the capacity to make the proper adaptations. In these cases, extinction most often occurs. And change can be subtle. many water animals such as sharks have undergone very little change since prehistoric times. Becoming smaller and faster to adapt to changing food supplies. Once the dinosaurs and other great lizards died out there was no more need for immense size. this you have the modern shark. Look at crocodiles. as they became more water based lizards their eyes moved to the top of their head. Another adaptation to meet new needs.

The traits that work the best are passed on most often and soon become the norm, spreading all across the gene line. Darwin and Wallace’s work was brilliant for it’s time and only became more so as time moved on. Very few of Darwin’ s predictions were wrong, and the main crux of his theory is no longer questioned in educated circles. Evolution is just fact. There is no denying it. Darwin’s work has been expanded on and proven time and time again. Wallace’s  theory of natural selection is the main linchpin of evolutionary thought. I would call them great men but that’s a huge understatement. They changed the world.

Well, hope you enjoyed this brief history of evolution.  And I do mean brief. I encourage anyone wanting a better understanding to follow up on the ground work I laid out.  There is much to tell. You’ll notice I didn’t get too much into the biology of it all because I hate biology.