It was reported today that 40% of Americans believe that God created humans, exactly as we see them today, approximately 10,000 years ago. That’s a startlingly large number who don’t believe in evolution through Natural Selection. Interestingly, 38% do believe that humans have evolved from less complex organisms, but that God had a hand in the process. I say this is interesting because the natural world seems to be battling the supernatural one, and while the supernatural one is leading, the balance appears to be tilting. One has to consider if the 38% of respondents who today believe God helped evolution along once believed in direct creation by God. Their change in beliefs could be called an evolution in their thought process if I were prone to the use of puns.
I am not a scientist, nor have I ever played one on TV or in an off-Broadway production. I think that makes me the perfect candidate to explain the beauty, simplicity and logic of Natural Selection to the non-scientists who like to read blogs. I’ll bet that if you’re currently in the 40% of non-believers in evolution through Natural Selection, I can bring you around. I won’t do this all in one post, in order to keep them brief and digestible, so let’s start with the basics.
1. Variation. If you look around at any animal or plant, including the human animal, you’ll find lots of variation. A key to understanding Natural Selection and how it works in nature is to understand the difference between a species and a variation. Species are defined as organisms that can breed with a similar organism and produce a fertile offspring. A variation is just a descriptor for the differences between the organisms of the same species.
Let’s take a bird like a finch for example. There are lots of variations in their beaks, the size and shape of their wings, the shape of their heads or length of their tail feathers, etc. A male and female finch can produce fertilized eggs, which will ultimately hatch baby finches that can grow into adult finches and keep on producing finches. A finch can’t do that with a pigeon. So finches and pigeons are different species.
2. Heredity. We know that physical traits are passed along from parents to their offspring. One of the first things you’ll often hear from someone who is seeing a friend’s baby for the first time is that he or she has his mother’s eyes or his father’s nose. So we intuitively understand heredity. There are certain traits that are positively passed along from parent to offspring.
3. Limitations in the ability to reproduce. This is an important one to understand. Let’s consider our finch friends again and put them somewhere in nature, not in a cage in someone’s grandmother’s house. There will be limits to the amount of space available for nesting, materials for nesting, food for their young, etc. There will be environmental factors like temperature changes and of course, humans may encroach on their natural habitat by tearing some of it down for a housing development and a Super Wal*Mart. Some of these finches will not reproduce before the end of their life span. Whether from disease or lack of food, these finches die before being able to reproduce.
In any situation where the above three conditions exist, it is inevitable that we will get evolution, i.e. changes in living organisms over generations as they adapt to their environment and pass along heritable traits. The variations of finches that are able to reproduce will pass along those heritable traits we talked about, while the variations that weren’t able to reproduce won’t be represented in the next generation.
Think about how simple, elegant and perfectly natural this process is! If we check in on our finch friends after a few generations, we may find that the finches with the longer beaks seem to be everywhere, while the short-beaked finches with the slightly shorter wingspans aren’t around anymore. At least they’re not around anymore in this specific geographical environment where we left them. We can logically deduce that the longer beaks and longer wingspans gave these finches an edge in fighting for limited nest space and food. They reproduced at will, passing along those heritable traits to their young. We have evolution through Natural Selection my friends. The finches in our test environment, faced with natural conditions that favored some variations over others, are now represented almost exclusively by the variation that survived and thrived. As time passes, the other variations will disappear completely from our test environment.
You can now apply those same rules to all living organisms in our test environment; worms, sunflowers, pine trees, lizards, rabbits, etc. They will all face the same pressures to survive and thrive and the variations best suited for this particular environment will mate, feed their young and pass on the physical traits that allowed them to flourish. Imagine a few centuries go by and we are able to check in again on all of the species we were keeping on eye on. We may be stunned to find the changes in each one. The light-colored rabbits may be all gone, eaten by predators, while the darker colored rabbits are everywhere. Their coats gave them better camouflage from their enemies and they were able to reproduce, well, like rabbits.
So there’s our first lesson ladies and gentlemen. This is very basic yet should open the door to continued discussion of evolution through Natural Selection as we move to Part II. There is a price for admission though. I will ask you to share this first lesson with friends and family, especially if you know some of them don’t believe in evolution, because my hypothesis is they don’t know enough about it, which is why they don’t believe in it. Once they understand it, not believing won’t be an option because it’s impossible to not see the truth once you’ve seen it.