Evolution: Nature's Trial By Fire For Life
Find Us On Your Favorite Podcast Player Here
When you look at nature, there are so many life forms that seem to be almost perfectly adapted to their unique environments. Why is this? Were they just put there or is there some process that made them that way? This week, we are going to talk about the fascinating story and science behind the Theory of Evolution to give us insights into why we are the way we are.
Show Article Below!
The Story And Science Behind Evolution
Woodpeckers are amazing. Their talons dig into the bark on the side of trees perfectly so they can cling on. Their beaks are like jackhammers that blast their way through bark and then their eyes are sensitive enough to pick up any movement by insects.
When they find one, it’s game over for the bug. It gets snatched by the woodpeckers abnormally long tongue that wiggles its way into the cracks and crevasses of wood to leave no survivors. They are almost perfectly suited for their environment.
There are over 200 different species of woodpeckers, all slightly adapted to a different environment with a different skillset. While just watching them in the woods with all of your bird-watching friends is fun, what’s even more interesting is thinking about why the different species are different depending on their environment.
Today, we’re going to learn the story and science behind the theory of evolution, where many scientists kept observing different species and fossils to discover the process that makes every species uniquely adapted to its environment.
Early Thoughts About Evolution
The story of how evolution was discovered is a long one that goes much farther back than Darwin, who is commonly attributed the entire concept. Don’t get me wrong, Darwin was very instrumental in putting together a cohesive framework, but let’s get in the time machine and head back to ancient Greece.
Animals Transform From One To Another
The first two on record to have ideas related to evolution were philosophers named Anaximander and Empedocles. Anaximander wrote that animals could be transformed from one kind into another after enough time passed and interestingly that humanity came from some other animal.
Animals Are Made From Pre-Existing Parts
Then, Emedocles wrote on the possibility that animals were made up of variations of pre-existing parts. He thought that at the beginning of the Earth, there many monstrous looking creatures that were random assortments of all the body parts we see throughout animals.
He was the first to propose natural selection. The best combinations would survive, and the ones less suited to the Earth would die. I’m imagining a cow walking around with chicken feet and crocodiles with beaks instead of their snout filled with teeth. It’s hard to catch a water buffalo with a beak.
While there were a few other hypotheses like these tossed around, they never really gained much traction because they were greatly held back by the limited amount of knowledge surrounding biology.
Teleological Thinking Surrounds Science And Philosophy
Most of the studies revolving around animals, species, and biology as a whole was teleological. This means that philosophers and early scientists were more focused on explaining the natural world in terms of the purpose everything served rather than how everything arose. It was a completely different way of thinking, but before there was any background knowledge, it makes sense.
They were just trying to lay everything out and determine what it does and why it’s here. What is the woodpecker’s purpose on this Earth? What does it do and how does it fit into the world? They weren’t necessarily concerned with how the species got to its current form.
Aristotle’s Great Chain Of Being
For example, in the 4th century BC, Aristotle came out with his work called scala naturae, or the Great Chain of Being. In this, he ranked all living animals in a hierarchy with plants on the bottom, then lesser animals and all the way to humans being the supreme lifeform on top.
In line with this map Aristotle made, the philosopher Augustine started to incorporate religion into this model by saying God created all of the beings on Earth. Everything we see was created by God precisely how he wanted.
Religious Thought And The Dark Ages Slow The Theory of Evolution
In the Medieval ages, there really wasn’t much movement in the Theory of Evolution or the thoughts of those early philosophers. Religious ideas putting God as the ultimate creator slowed the progression of alternate ideas. It stopped people from looking at our reality differently.
There really wasn’t a whole lot of anything science related going on during the Medieval Ages. Of course some went on here or there, but during the Dark Ages, it was dark because it lacked enlightenment and progress. We will have to wait through these times until we get to some more developments.
The Theory of Evolution Finally Advances
Let’s hop into the time machine again and go all the way to the 17th century. A German philosopher named Gottfried Wilhelm Leibnitz started writing on the continuity of life. His idea was that, between all of the lifeforms on Earth, there is some sort of continuity between them.
He was inspired by the work of another 17th century philosopher named Descartes who explained nature as a mechanism. It was both alive, and lifeless. This makes sense to me, at least.
Nature Is a Mechanism of Life, Death, and Change
We see life all around us with various plants and animals roaming around, but at the same time, nature can also be looked at as a mechanism of creation, life and death. This cycle continues seemingly forever. The natural world also contains weather systems, the oceans, landscapes, seasons and much more that really do make it plausible to look at it mechanistically.
Anyways, Leibnitz stated that there is an order that follows one after another, but also said that this is led by God. The order of things isn’t known to us, and God put it in place, but there is a definite mechanism by which nature follows. In this, he stated that all lifeforms sort of flow into one another, rather than always being discrete categories.
While these ideas sort of lean towards there being some sort of evolution occurring in the natural world, they are still a bit off from what actually occurs and incorporate a lot of religious ideals rather than scientific. I’m not saying that incorporating religious ideals into the theory is necessarily wrong, but it isn’t at the level of modern science.
However, it wouldn’t be long before we see some landmarks in the history of evolution. In the 18th century, a German philosopher named Johann Herder was one of the first pioneers of modern evolution.
Life From Inorganic to Organic
He laid down a doctrine of the continuous development of life all the way from inorganic to inorganic, so earth to plants, plants to animals, and then animals culminating into human life. Everything is united in one continuous flow and develops based off of fixed laws set by nature.
This system of nature is trying to reach perfection, and humanity is just one point in its history. He wasn’t quite sure what the future would hold, other than it would always continue to push for more perfect lifeforms.
Where Did Life Come From?
Also in the 18th century, a famous philosopher named Emanuel Kant started teaching some of the ideas surrounding evolution in what was called the ‘theory of descent’. He noticed that there was some sort of common ground among most life and made the hypothesis that everything came from some sort of common descent.
He theorized that it would be possible for animals like the chimpanzee to develop the ability to walk over time, start using tools if it realized the value, and possibly even learn language. From these small improvements, maybe one day you would reach mankind.
Philosophers were now observing the world around them and trying to figure out what made life the way it was. Although there weren’t many experiments being done, constant observation and deep thinking led them to the idea that one life form might change over time and turn into something completely different many generations down the line.
These ideas were groundbreaking and his successors started to spread them and make their own revisions. There were some kind of ‘woo-woo’ ideas about evolution that I thought were pretty interesting.
One is that the point of evolution was so that nature could have a mind so that it would be conscious and able to reflect on itself. So, that’s what humans are. We as humans are nature’s consciousness. Now, I’m not sure if there is any science to support this claim and it’s sort of the cliché philosopher way of thinking, but hey, it’s cool.
Life Is Always In One Continuous Motion
The idea that life was in one, continuous motion towards new forms and that all life comes from something before it was getting spread and grown upon. The development of life in these hypotheses went from plants, to the animal kingdom, and then up to humans.
Still, many of these thoughts on evolution had traits from the teleological thinking we talked about earlier that was widespread throughout the ancient world. They were thinking of life based on purpose, and then how we get to the lifeform with the most purpose, which was presumed to be humanity. So, most models of the continuous change in nature were centered around the idea that the goal was to develop humans.
Life Must Change With Its Environment To Survive
We’re now barreling towards the 1800’s, where much of what we know to be evolution today was found. In 1809, Jean Lemark, a French zoological philosopher, made some progress in the area of how changes in lifeforms actually occur over time.
Jean postulated that when the environment changes, the form of the life must change as well to survive. On the subject, he wrote:
“If a new environment, which has become permanent for some race of animals, induces new habits in these animals, that is to say, leads them into new activities which become habitual, the result will be the use of some one part in preference to some other part, and in some cases the total disuse of some part no longer necessary.
Nothing of all this can be considered as hypothesis or private opinion; on the contrary, they are truths which, in order to be made clear, only require attention and the observation of facts.”
Ideas of Possible Examples of Evolution
He then went on to explain how snakes got rid of their legs so that they could be more elongated, hide in the grass, and pass through narrow spaces. The snakes would have used their legs less and less, rendering them useless and actually a hinderance. Since the snakes didn’t need these parts, they eventually went away.
On the other side of the coin, parts that get used more actually grow into more useful forms. Frequent use of a body part or organ makes it stronger and enlarges it.
Jean gives an example of giraffes, which live in places in Africa where the soil is arid and barren. He writes: “the soil is nearly always arid and barren, so that it is obliged to browse on the leaves of trees and to make constant efforts to reach them. From this habit long maintained in all its race, it has resulted that the animal's fore-legs have become longer than its hind legs, and that its neck is lengthened to such a degree that the giraffe, without standing up on its hind legs, attains a height of six metres (nearly twenty feet).”
This was one of the first concrete theories explaining why evolution of lifeforms goes from one to another. Although not completely correct, he did have some good ideas. The idea of environmental pressure rendering some body parts more useful than others is a cornerstone of the theory of evolution.
Observing Nature and Collecting Data to Support Evolution
So, at this point, there is actually a pretty solid groundwork containing ideas around life being in a constant state of evolution, continuously changing from one form to another. It was a mechanism of nature that was trying to perfect life.
However, there isn’t much actual science going on here involving experiments, data, and examples of how the change takes place. Also, everything is sort of in bits and pieces. There hadn’t been one coherent theory put in place stating how one thing led into another.
Before we get to a major breakthrough in the evolution story, I also want to say that there was evidence coming from different parts of science that would go on to be used.
Archaeological and Biological Evidence
One was that fossils of animals no longer alive were being found, leading to the idea that there used to be species on Earth that no long exist. This led to the idea that life may have possibly been around for a very long time and also that there was some force that drove the species to be extinct.
The next was done by early biologists and embryologists that were studying animals and humans being born. They noticed that some of them would have mutations and variations in the way they looked. This all might seem a bit mysterious right now, but it will all make sense soon.
Charles Darwin & Alfred Wallace Change Evolution Forever
In come two scientists named Charles Darwin and Alfred Wallace. They both found inspiration in an unusual place: a book on economics. A 1797 book called Essay on the Principle of Population warned about the policies being put on the poor because this would lead to extra population growth.
An uncontrolled growth in population would mean there would be less food and resources available, bringing down the quality of life for everyone. Regardless of your views on this idea, Darwin and Wallace both thought about the idea that animals also experience population pressure, or in other words, fewer resources available as populations grow.
Limited Resources Means Some Members of a Species Won’t Survive
The world should be covered in layers of bugs, bacteria, rabbits, and anything else that reproduces quickly, but, it isn’t. The reason species don’t overrun the planet is because there is only a limited amount of resources available to each species. As a species increases in population, some won’t make it.
They then went on to reason why some make it and some do. This struggle isn’t due to pure chance. It isn’t that some members of a species happen to stumble upon enough resources to stay alive. No, the real reason is that there are some members of the species who have traits that make them more able to survive their environment.
Some Traits Allow Life To Survive Longer
Darwin and Wallace both independently realized that if animals had some trait to allow them to survive the natural world and then breed more successfully, it would lead to that specific organism having more offspring. Then, that trait would become more commons as the generations kept reproducing.
Darwin spent a lot of time with pigeon breeders and examined their methods of selection and found that to be a good analogy for evolution. The breeders selected for pigeons that had a larger neck ruffle. Generation after generation, they would only let the birds with the largest neck ruffle reproduce to make the next generation all have bigger ruffles.
Natural Selection Is All About The Ability of a Species to Breed
Using ideas such as this, Darwin and Wallace both thought that this too could happen in nature, except instead of something being at the head controlling it, instead the environment the animal was placed in would only allow individuals with certain traits to breed. So, when the environment changed, there would be new challenges forcing the organisms to change with it in order to survive.
Darwin started his work in the 1830s and had a huge pile of data supporting his hypothesis. One of his supports was his famous work with Finches in the Galapagos Islands. He noticed that finches on the islands were significantly different than finches on the mainland.
They were so different, in fact, that some of the specimens he collected were mistaken for different birds until a bird specialist colleague of Darwin’s was like, “uhh those are finches man”. Their beaks were different, their size was different, and they were colored much differently. There were even differences between the birds on islands neighboring each other.
Some Species Have Come From a Common Place
He surmised that all of these finches must have come from a common place since they were still all of the same bird type.
Darwin wrote, “Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends."
Finches Have Beaks That Are Specific To Their Environment
So, in the example of the finches, Darwin noticed that the shapes of the beaks exhibited by the birds was specific to their food source on the island. Islands with harder nuts had birds with short, stout beaks that were optimized for cracking the heard shells.
Islands with smaller seeds had birds with smaller, elongated beaks that worked well for picking up the small seeds. In the end, he found 13 different species when there were there were only a couple known to the close mainland of South America.
He also realized that within any species, there is actually quite a bit of variation. In the case of the beaks, the logical conclusion was that some beak shapes were more suitable to the specific environment the animal was in. If a finch with a long, less powerful beak had to use it to crack very hard shells, it just wouldn’t get as much food as another finch with a shorter beak.
Nature Pushes Evolution Through a Fight For Resources
What these two scientists discovered was the process of natural selection. It’s the way nature pushes evolution. It does this when an environment puts pressure on the organisms fighting for resources. When there are too few resources for everyone to survive, certain traits favorable to the environment they are in will yield more resources leading to better survival and allow the organism to breed more.
Then, the next generations will have more of that trait and pass it on if it benefits them, and it grows into more and more usable forms that are always allowing them to reproduce more. This could go on to make two groups of the same species into something completely different.
The Origin of Species Is Published
Darwin finally came out with his seminal work in 1859 called “The Origin of Species” and it completely changed science forever. It went on to become a best seller and was widely distributed. Wallace came out with what was more of a paper on the subject a year earlier, but his name didn’t catch as much traction.
I think that reason Darwin is attributed with the idea was that he had enough information and data to write a comprehensive book that became widely distributed. So, everyone knew Darwin’s theory of evolution and not Wallace’s.
After all we’ve learned so far, we know that Darwin clearly didn’t engineer the idea of evolution, natural selection, or really most of what was contained in The Origin of Species, but what he did do was carry out necessary research to back up his hypothesis and then make a conclusive document that fully encompassed the idea.
Darwin Is Responsible For Spreading the Theory of Evolution
He was ultimately responsible for spreading the ideas of evolution through the 19th century and moving forward those ideas. This was not easy though, as the theory was met with widespread skepticism from other scientists holding onto their dogmatic views of the way the world and nature worked along with strong opposition from the church.
If all species are in a current state of change solely depending on their environment, where does that leave room for God and religion? What role does it play? Were humans created in our current form or do we have along history of change that brought us to this point. Darwin was simply stating facts and observations from the natural world.
Interestingly, Darwin believed the Biblical creation story the stated God created everything in 7 days and set the Earth off in its current form until 1837 when he made his trip to the Galapagos Islands.
Criticism of The Origin Of Species
Some of his 19th century critics said that the data Darwin found was misinterpreted. The real cause for the variation was that God had put each of the birds in their unique environments and engineered them to be successful. At the time, it was actually hard to come up with an argument against that though.
This has always been the problem with the intersection of religion and science as they are two completely different ways of looking at the world. Religion uses personal beliefs to allow someone to come to conclusions about the world around them.
Science, on the other hand, relies on data, experiments, and observation to come to conclusions about the world. The issue is that when a claim such as God created everything perfectly and with a specific purpose, it’s hard to do experiments to refute that because God cannot be the center of a research experiment. It can’t be tested.
Through the 1860’s, Darwin further refined his hypothesis around evolution and started to realize that this process was ‘the survival of the fittest’. In other words, natural selection will cause the most fit members of a species to survive, and then the least fit will die.
The English Moth Example Of Evolution
Another example of evolution that was discovered in the 19th century was the change of moths in industrial English cities. In many moth species, there were variations in wing size and color observed. However, the industrial revolution caused a huge spike in coal burning that turned many of the trees in certain areas to be dark in color.
When a brightly colored moth would land on these trees darkened by coal soot, it would be much easier for birds and other predators to spot, and it would get eaten. This was a sad time for moths everywhere. The soot covered trees were causing a slaughter brought about by the birds.
The Moths Adapt To Darker Trees
There is a silver lining though. The color variation led to some moths being darker than others. This meant that when they landed on a soot covered tree, they blended in much better and therefore survived longer, and following this they were able to breed more. The environment started to favor dark colored moths.
This happened generation after generation and quickly led to changes in how the moths appeared. By 1895, 98% of moths living in industrial cities were very dark in color.
Interestingly, in the 1950s and beyond, English cities made great strides towards increasing air quality and decreasing the amount of soot leaving factories. The result was that the trees began to grow normally again and there brighter color was restored.
The Moths Re-Adapt To Lighter Trees
Now, the moths that had the grit to survive on the darker trees and their following generations that turned very dark were again at a disadvantage. The bright trees meant that their dark color would make them easier to spot than lighter moths and they were savagely eaten by the murderous birds. They couldn’t seem to catch a break.
The moths were resilient though and faced the tough task ahead of them courageously. Natural selection began to favor light colored moths and because of this, the entire moth population started to change back to their original color. This trend in the moths was well documented at the University of Liverpool.
What Is Meant By ‘Survival of the Fittest’?
Before we go, I want to talk about the phrase ‘survival of the fittest’. At first glance, it seems like Darwin is saying that the biggest and strongest or even that the smartest will survive. However, while in some cases this is true, it isn’t what Darwin meant by the phrase.
From an evolutionary perspective, fittest just means that the individuals best suited to their environment will be the most likely to survive to breeding age, making their offspring contain the traits that made the parents successful.
Dark colored moths were more fit than light colored moths because their dark wings allowed them to reproduce more often and then have more offspring that looked like them. It really had nothing to do with their intelligence, strength or size. Then in the 1950’s, the environment changed to make light colored moths more fit.
In the two decades following the initial publication, Darwin went on to publish an additional 15 scientific books expanding on the subject. Darwin also seemed to insist that Alfred Wallace get some of the credit and that it was a draft Wallace’s paper that inspired Darwin to put all of his research and theories into a book.
Missing Pieces From The 19th Century Theory of Evolution
One huge piece that was missing from the models of Wallace and Darwin was genetics. If natural selection were always selecting for the most fit individuals, over time we should arrive at one homogenous organism where they all look the same and are all the most fit. This, however, is not the case.
It turns out that every following generation has variation, and there was no good explanation of this without knowledge of how heredity or genetics work. However, a monk in central Europe named Gregor Mendel discovered the laws of heredity which gave a lot of answers to these question.
Mendel’s Law of Inheritance
In a previous podcast, we took an in-depth look at what Mendel found and how he did it, so if you’re interested go take a peek at the episode I did on plant breeding. While you’re at it, go check out the episode we did on DNA as well. Both of those really illuminate some of the background on how evolution works.
Anyways, in short Mendel found through plant experiments that offspring contain a combination of traits from the mother and father. With this knowledge of genetic recombination, it explains why there is still so much variation in offspring and also explains some other aspects of evolution as well.
It is this random combination of DNA from the parents shown in the offspring that will either make it more or less fit. Each child organism is sort of like an experiment, testing its fitness in the environment it was born in. Some combinations are complete failures, making the offspring unfit and leading it to die. However, some are success and make them even more fit than their parents were.
Knowledge of Genetics and Genetic Mutation
Another aspect that they missed due to lacking information was another driver of evolution through random genetic mutation. Since there wasn’t knowledge of genetics or how it works, there was no way that they could have figured this out.
What happens in all of us and all life is that as DNA is passed from parents to offspring and then replicated in the offspring to make all of their cells, sometimes the process of making copies of DNA goes haywire and there are mistakes made.
Random Mutations Can Change Fitness
These random mutations change the organism and how it functions. Sometimes, the mutation isn’t noticed, many times, the mutation is fatal, but in rare cases, the mutation may actually be helpful. I know this is sort of vague, but there is a lot of genetics in the background and we could go on for hours about how this works.
In a nutshell, lets go back to the moth example. Imagine that instead of there being both dark and light moths, instead they are all light. When the soot covered trees come about, there would really be no good way to cope and maintain their fitness.
Now imagine that when two moths come together to reproduce, something goes wrong and there is a mutation in the offspring’s genes that codes for color. This mutation causes the wings and body to be slightly darker. Now, that random mutation is actually favored in the environment the moth lives on, increasing its fitness.
When that mutated moth reproduces, its offspring will have the mutation and some of them will be darker. This is a short term example that is heavily influenced by humans, but what happens in nature is much more drawn out.
This process would naturally happen over thousands or millions of years with countless numbers of offspring. Like I said, each offspring is sort of like a miniature experiment testing a new lifeform in the environment it is born.
Most Mutations Are Failures, But Some Actually Help
Like I said, many mutations are failures and often fatal. In an alternate universe, the moth could have had a failed mutation in its gene coding for wing size and could have been born with deformed wings. If this happened, it would be very unfit for its environment and natural selection would snuff it out pretty quickly.
However, the mutation could have made its wings perform better, and therefore it could have been more fit. Like I said, the sad reality of life is that most mutations are failures, but the story of the evolution of life is like one big experiment with many tests going on simultaneously, so just by luck, some will be successful.
Evolution Has Become Widely Accepted
Throughout the years following Darwin and Wallace and all of the hypotheses of scientists and philosphers before them, we have learned vast amounts of information supporting their theory. Now it’s widely accepted that life as we see it today has evolved from common ancestors to fit individual environments.
It’s hard to wrap our minds around because we really have no perception of how long this has been happening. What does one or two billion years mean to us when we have only lived for a few decades?
Putting Time Into Perspective
Here is a good thought experiment that helps me with our problem of putting time into perspective. Imagine the earth was formed at midnight and that the present moment is 24 hours later. If the timeline of Earth’s history were condensed to a 24 hour period, modern humans have only been around in two minutes.
If midnight the next day is present time, humans have existed since 11:58:43 PM. That is nothing compared to the long history of the Earth. Then, digging a little deeper, let’s do the same thought experiment on humans.
The species of homo sapiens comes about at midnight. We would have to wait all the way until about 11:46PM the next night to get to year 0 on modern calendars. So, 2000 years ago is only 14 minutes away from present if the timeline of homo sapien existence were condensed to 24 hours. Then, homo sapien existence comprises just over a minute on a 24 hour timespan of the existence of the Earth.
I want to say that the timelines we have now are very rough and always subject to change when new evidence arises, but it keeps getting refined further and further. I think in the future an entire episode will be devoted to the specific evolution of humanity, so stay on the lookout for that. This episode would get way too long if I dove into that rabbit hole.
We Now Have Insight Into Where We Came From
The theory of evolution turned the science and religious worlds upside down. We now have a reason for how life is the way we see it other than ‘it was just created this way’ by some divine power. The theory of evolution is almost unanimously accepted throughout the scientific community as a whole and offers deep scientific insights into where life came from.
While there are still a lot of questions to be answered, because of the dedication and risks of scientists up to Darwin and beyond, we now have insights as to where we came from. I can’t wait to see what the future of science will continue to tell us about how we were shaped as individuals by evolution.