Few things in science cause as much public confusion as the Theory of Evolution. While a number of great resources have already effectively elucidated the concept, including a video I’ve embedded in this article, I think it is valuable to repeat and expand upon these resources in a public fashion, lest The Theory fall out of common knowledge.
It is a credit to evolution’s founder, Charles Darwin, that he was correct about so many of the basic tenants in his original publication, The Origin of Species. These principles can be generally summarized into four statements:
- Variation, which arises through mutation, exists within and between populations for every trait.
- More individuals are born into a population than can survive (usually because of the scarcity of resources).
- Traits are passed down from parents to their offspring.
- Individuals most fit to survive in their environment generally do (Natural Selection).
Something many people fail to realize about evolution is that the entire theory pretty much boils down into the aforementioned points. Much of the controversy that has been held up by various anti-evolution groups centers around points not affecting the theory at all. In fact, if the concepts of evolution were suddenly found to be false, our understanding of the nature of species would be a very poor one. Let’s attempt to identify just what evolution DOES specify and leave be the things not covered by the theory.
First of all, it is helpful to think about individuals of a certain species as free-floating molecules. In fact, this is pretty much how microbiologists have to view microorganisms, proteins, and other microscopic components of the biological world. Imagine that these individuals are constantly moving about and encountering food, predators, good environments, and bad environments. If you zoomed in on any one individual and followed its life, it would represent one possible jagged line. That individual would also have a specific set of qualities or traits that are the results of its parentage.
Now, zoom out and look at all the individuals in the population. They all have their own jagged lines that make up their physical movement and interactions as well as their own unique sets of traits. Many of the individuals will be similar to one another and many may have similar “lives,” but when added all together there is an enormous amount of chaos going on in a single population of any sufficient size. This is NOT evolution, but instead the conditions required for the evolutionary process to occur.
From these conditions it is very easy to visualize the process of natural selection. Individuals essentially need to survive long enough to reproduce. Reproduction might only require mitotic division (as in microbes) or mating might need to occur (as in animals). In any event these are the first constraints. Then individuals face dangers from predators and dangerous situations (a fish trapped in a draining tide pool or a stag falling off a cliff). Lastly, individuals will compete with themselves and with other species for scarce resources such as food, water, and possibly space (a major concern of plants). The competition resulting from these conditions rapidly selects a smaller group of individuals who will create the next generation.
This process can be termed “natural selection” because conditions chaotically (not randomly), “select for” or “select against” a given individual. Note that nowhere in here is “survival of the fittest” a stated fact. Often the fittest do survive because their traits make it more likely, but if a chasm opens up in the earth and only a few individuals survive, then it becomes “survival of the lucky.” However it works, those who survive pass their traits on for another round and the cycle continues.
It is easy to see that over time, perhaps one year or thousands of years, that a such a chaotic population will not become uniform, but will collectively shift toward certain traits. If the shift is dramatic enough, new species emerge. Essentially a species is a group of individuals that are related enough to mate. When a population branches (which can happen for several reason), two groups can diverge and eventually lose the ability to mate. This is the basis for all speciation.
Regardless of what you have heard, this is really ALL there is to evolution. I have not spent much time refuting the claims of those who oppose evolution (despite the enormous amount of evidence in its favor), but the following video does an admirable job, so I will let it:
Why is evolution so important? Well, if you use evolution as a viewpoint and a tool when examining the world, some things fall into place and others don’t. When things make sense with evolution, it’s a good chance that we can figure out an organism’s history (especially with the rise of genomics). When things DON’T fit, then we need to reexamine the evidence and look for better solutions. Sometimes knowing the missing pieces of a puzzle are important if we are to understand the bigger picture.
Before we finish, I would like to give myself a tiny bit of credibility as a science writer. As of Saturday, I now hold a B.S. in Biology (conc. in Microbiology) from George Mason University. While my experience in the field is still limited, much of the theory is still fresh in my head and easy to put down in writing. Hopefully graduate school at the University of Maryland will help bolster that knowledge. Then I can pass it on to you, the reader.
Feel free to leave a comment or a question (I try to answer any reasonable ones) or hit me up on Twitter!