Upon a prompting from my popular and pompous brother in law, I have decided to write a blog about evolution. Of course, writing about such a complex subject in a short blog post isn't easy. There are going to be things that I leave out, and if you catch them I encourage you to comment below. (And, as usual, if I don't like your comment, I won't publish it).
Let me start by saying, if your going to discuss a subject, you better define it. So, what is evolution? Think about that question for a second, what do you think it is? Is evolution a fish slowly turning into a monkey, then slowly turning into a human? Where did the fish come from - perhaps a plant? You've probably heard evolution referred to as "survival of the fittest". Maybe the "fittest" plant evolved into a fish, into a monkey, into a human?
So, where did you land in your thoughts - what is evolution? Well, quite frankly there are DOZENS of different definitions, but I think the most easily understandable one is that evolution is a process that results in heritable changes in a population over time. Now, as long as you understand what "heritable changes" means, evolution becomes self evident. A distinction about this definition, as you will see, is that it is not "survival of the fittest". Indeed, something doesn't have to be "better" to be said to have evolved.
Essentially, heritable changes within a populations means a change in allele frequencies within a population. Easy there fellow, al-eeeelle, the hell is that? Well, unfortunately this is the one paragraph where I'm going to require you to learn some biology. For the purposes of this blog, picture every human with their own individual candy necklace - unless they're identical twins - that makes up their DNA. A gene is a portion of side-by-side candies within the necklace that codes for a protein. Now, backing up a second, each individual persons candy necklace actually came from a mix of 2 original necklaces: their moms and their dads. So, imagine each individual with 2 candy necklaces around their neck, one from their mom, one from their dad. In imagining this, it's easier to understand that any gene must have a contribution from both your mom and your dad (in general). Basically, biologists call the separate contributions alleles, in that 2 alleles make up 1 gene. Sometimes, certain alleles are dominant over other alleles. For instance, brown eyes are dominant over blue eyes. If your eyes are brown, it means you have at least 1 brown eye allele. If you have blue eyes, that means both of your eye colour alleles code for blue. Interestingly, this means two brown eyed people can have a blue eyed child, but 2 blue eyed people cannot have a brown eyed child*. Now, for the process of evolution to occur, allele frequencies must change within a population. In our current example, conceptually, lets say blue and brown alleles existed in a population equally. Knowing that brown is dominant over blue, we would assume that there would be more brown eyed people, but the alleles would still be 50% blue, 50% brown. However, if there were a catastrophic event in Sweden, and a bunch of blue eyed individuals got killed, that would mean the frequency of blue eyes in the global population would decrease. Eventually (and it will eventually occur on Earth without such an event) everyone will have brown eyes, and you could say the population has evolved. What is important here, is that a change in eye color - as far as I know - isn't a benefit to the human species (though perhaps their is some sexual preferences). This is where the misconception that evolution is "survival of the fittest" is refuted. Indeed, a brown eye doesn't perform better than a blue eye, yet the population will eventually be taken over by brown eyes. This is not to say that survival of the fittest isn't something that exists. Indeed, it does exist. If an allele benefits an organism so that it can out compete fellow organisms amongst it's population, that allele will increase in frequency amongst a population. (A great example is the antibiotic resistance allele, which gives bacteria resistance to antibiotics, and is increasing in frequency world wide as bacteria without the allele are killed off from antibiotics). However, regardless of whether an allele is beneficial or not, it's frequency changing within a population is what evolution is.
BROWN ALLELE x BLUE ALLELE = BROWN GENE = BROWN PROTEIN = BROWN EYESBROWN ALLELE X BROWN ALLELE = BROWN GENE = BROWN PROTEIN = BROWN EYESBLUE ALLELE X BLUE ALLELE = BLUE GENE = BLUE PROTEIN = BLUE EYES
Simply to hammer home what evolution is, lets examine what evolution is not. Firstly, evolution is not something that occurs to an individual. As noted in the definition, it must occur to a population. If I grow wings tomorrow, that is not evolution, it is a mutation. If I subsequently have children with wings, and they have children with wings, then wings become prominent in a population, that is evolution. Secondly, evolution is not a monkey turning into a human. Evolution is a process by which monkeys and humans shared a common ancestor, and each species went their own separate way from that ancestor. It's the equivalent to saying a Mac is different from a PC, but both of them started from a calculator. Neither turned into the other. They followed the same process, from the same start, and became two different systems. Finally, and culturally most importantly, evolution is a process that determines how single celled life has transitioned into the complex forms of life we see on Earth today. It is not an explanation for how life began. Instead, it explains the mechanism by which life has changed over the past 3 billion years.
Clearly, I've opened a can of worms with my rhetoric blogosphere. Not only is this a subject that is important scientifically - for instance in the understanding of bacterial behaviour to antibiotics - but this is also an important subject culturally. If you accept the evidence that exists for evolution - none of which has been presented in this blog, but in my personal opinion is overwhelmingly suggestive that evolution has and continues to occur - there are a ton of social ramifications.
I think my favorite consequence of evolution as a fact is that it scientifically disproves the ideals in society that have for hundreds of years caused nothing but heart ache for humanity. Importantly, data for evolution shows that all human kind originated in Africa from the same small population. Knowing this, how could you say that one race is superior to another if we share a great (x10^100) grandmother? How does the fact that we all come from Africa change the rights of natives? How does our common lineage change intercultural tensions worldwide?
And the ramifications of evolution aren't limited to human rights. Frankly, you can't view humans to be superior to any other species which arrived on this planet by a parallel process. They are our equals. Additionally, evolution provides scientific evidence for how we have become what we are. Obviously, this is of great cultural significance. For the first time in history, we are using logic and reason to explain our existence. We know why our ears, noses, and eyes work the way they do, and we no longer need scriptures to provide other explanations.
Evolution is not a religion, nor is it an alternative to religion. It is a fact. It doesn't tell us there is no afterlife. It doesn't tell us how to behave, or what morals you should live your life by. Instead, it shines light on the incredible unlikelihood that we are even existing here by explaining how it happened. By understanding evolution, you may find yourself enjoying life a little more - knowing how lucky you are, just to be here.
*I like the eye colour example because it illustrates how 2 different alleles influence a gene. But, if you think about it, it also shows how a population can have a bunch of different alleles (green eye alleles, albino alleles, etc) and it is the change in frequency of all these alleles together - not just blue and brown - that is the process of evolution.
