One of the most underappreciated holidays in the United States has finally arrived – Darwin Day. On February 12, 1809, Charles Robert Darwin was born in Shrewsbury, England, and was the fifth of six children. While at first he carried after his father by pursuing medical science, he eventually shifted his focus to natural history when joining a student-led group during his second year at University. It was here that Darwin’s entire world was challenged when he was presented with a more materialistic view of the universe that seemed to challenge his religious understanding of science.
Throughout his time at University, Darwin was confronted on several occasions with early ideas of biological evolution, but these ideas lacked the rigorous experimentation needed to form a solid scientific theory. Charles took these ideas and ran with them during his famous trip to the Galapagos Islands in 1831 where he realized each separate island had similar animal life, yet each species was perfectly adapted to the environment in which it lived. It wasn’t until 1859 that Darwin brought all of his research together into his famous book, “On the Origin of Species”. He had done what no other scientist had – proposed a natural theory to explain the origin of biological diversity.
The work of Charles Darwin drastically impacted the scientific world and has opened a window into the universe that continues to astonish to this day. But while the scientific community has been busy further developing the theory with unprecedented accuracy for over a century, many are still unsure of the validity of his theory – and I don’t blame them. The idea of biological evolution takes place on such a large and incomprehensible scale that truly understanding it is often a challenge. Without an accurate understanding of gene mutation, niches, or even the age of our planet it is easy to understand how the idea of humans sharing an ancestor with modern bacteria seems absurd.
However, science often deals with the absurd, and that is what makes it so wonderful. Where as personal subjective beliefs seem to always make sense in our minds, the objective revelations discovered through science often challenge what we see as possible. It is only when we set aside our ego and look at the facts that we can begin to understand the true history of how our species became the planet shaping beings that we are today. So regardless of your current beliefs on the topic, take some time to at least try to understand why this theory has had such a large impact on modern society.
How Does Biological Evolution Work?
The idea itself is relatively simple. It’s only when you allow it to play out for billions of years that it becomes complex.
Imagine a modern bird that attracts it’s mate with the bright colors of it’s feathers. This particular animal has the most vibrant feathers of any of the birds in it’s patch of jungle, so it quickly finds a female to reproduce with. When these two animals mate, 50% of the males DNA and 50% of the females DNA will combine in the egg to form a new individual who will share similar features to both parents. However, as this process is taking place there are often mutations that can cause drastic changes in the resulting children. In this scenario, let’s say they give birth to three children. The first of the children has a mutation that causes it’s feathers to be more dull than that of it’s father. The second child also has more dim feathers, but is also a much better flyer. The third child has even brighter feathers than it’s father, but is also a much worse flyer.
In the lives of each of these birds they face many challenges. Bird #1 tries securing a mate, but it’s feathers are too dull and the ladies are not interested, so it is unable to reproduce and pass on it’s genes for dim feathers. Bird #2 also has dim feathers, but because it is such an excellent flyer it is able to escape the predators that typically keep members of it’s species from traveling out of their normal habitat. It finds a new place to live with fast flying females that are more interested in speed than color, and mates – therefore passing on it’s dim feather and fast flying genes. Bird #3 has brilliant feathers, but can’t fly very well. So instead of showing off it’s color in the tree tops like the rest of it’s species, it tries to attract a mate on the ground and happens to find a female that is interested.
Each of these birds has created a change within the ecosystem. Bird #1 does not pass on it’s genes, so dim feathered birds do not continue to reproduce – at least not as members of this particular lineage. However bird #2 was able to reproduce, and since women in it’s new community don’t care about feather color as much as flying capacities, it passes on it’s genes and creates a future colony of fast flying dull colored birds. Bird #3 reproduces as well, but has changed the way the game works by giving birth to birds that will search for mates along the jungle floor instead of the canopies.
As each of these birds continues to reproduce within their separated communities, the mutations that make them unique may become emphasized. Dull birds become more and more dull. Fast birds become more and more fast. Given enough time, the genes of each of these separate groups will become so different from one another that they are no longer able to reproduce with each other. Therefore, new species of birds are created. This is a very slow process that deals more in gradual changes than big leaps. If these birds can become separate species within just a few generations, imagine what billions of years could do.
How do we know life evolves this way?
When life was still composed of single cells, something amazing happened. A cell absorbed another that had a drastically different function and instead of destroying it, it decided to give it a home inside of it’s own body. The smaller cell was an early mitochondria that was not destroyed because of it’s ability to produce energy for it’s host. When the host reproduced through mitosis, it not only made a clone of itself – it made a clone of the mitochondria within it’s own body. Because of this event, all life today actually has two separate sets of DNA within each cell. Nuclear DNA (located inside the nucleus of each cell), and mitochondrial DNA (located inside the mitochondria of each cell). By studying mitochondrial DNA, scientists are able to roll back the clock on human evolution and find the single ancestor that all humans have descended from. But this isn’t the only way scientists study evolution.
In addition they also look at fossils within rock layers all over the planet, and the evidence is some of the strongest of any scientific theory. No matter where you look on earth, the layers always match up. Fossils from the Jurassic period on one side of the planet will always have similar life forms to fossils found during the same period on the other side of the planet. If even one fossil was found that seems to cross geological eras in unpredictable ways, the entire theory of evolution would be challenged. Yet, after over a century of scientific research, not one issue has been found.
Scientists also study homologies to determine common decent. This is often used when comparing the bone structures of modern animals to those of the past. Using this method it is possible to follow the fossil history within a specific region of the earth to see exactly how and why certain mutations were beneficial.
But perhaps the most powerful evidence for biological evolution is the fact that it is happening all around you right now! With the increase of elephant poaching in Africa, some elephants have begun giving birth to children without tusks, thereby giving poachers no reason to poach. Elephants with the “no tusk” gene are much more capable of surviving within their current habitat, so the gene will be passed on. Given a few thousand years, we could eventually have a whole new species of elephant that looks drastically different than those alive today.
New species are discovered every year not because we simply haven’t found preexisting ones, but because new species are being made. Life is perhaps the most beautiful and diverse thing that our universe has created, and when you truly understand how massive and significant evolution is you can’t help but be fascinated by it. What you have read today is a very simple explanation of evolutionary biology, but thankfully there are plenty of places that you can read more into the subject.