As I wrote in Part I, there is a large percentage of the American populace who doesn’t believe evolution exists, that God created man and presumably other species as we see them today. My goal is to try to reach that percentage of non-believers and help them understand the beauty of evolution. I am not a scientist but a lover of knowledge. Let us learn together.
When we last spoke on the subject, we discussed Natural Selection and how different variations of the same species, better suited for their environments, win the battle for limited resources, reproducing at will and ultimately, over time, dominating their habitat. Other variations of the species will no longer be found in that environment. Let’s take a look at how our finches are doing in our test habitat.
Many generations have passed since we last visited our friends and life in the test habitat is flourishing. The finches have done quite well, although the large population caused many to fly further from the test habitat in search of food and additional nesting areas. Flora growth has been pervasive and miles of heavy jungle distinctly separate the two groups of finches from each other. The environments they each live in have some distinct differences and again, variations in the finches that are best suited to their environments succeed in reproducing, passing on the heritable traits to their offspring. The variations not as well suited, do not reproduce as well in this new environment and again, over generations, begin to disappear.
A hurricane causes significant damage to our test habitat, cutting down much of the tall flora and bringing some of our two finch groups back together. Some of the finches of the two different groups mate, but fail to produce any fertile offspring. The variations of heritable traits passed down over multiple generations have created enough of a genetic difference in these two birds that they can no longer reproduce. A new species of finch now exists through Natural Selection!
This is a very basic explanation of one type of speciation. It’s not meant to be a biology lesson, but a conceptual lesson so the 40% of Americans who don’t believe in evolution can start to come to an understanding of how it works. There are many ways the isolation of species can occur, with geographical isolation being only one. Ultimately if a segment of the population gets separated from the rest for whatever reason, and the new environment presents different conditions, the traits that get passed on through the successfully reproducing variations, over many generations, may lead to enough genetic differences that speciation occurs, i.e. a new species develops.
You will often hear talk of common ancestors whenever evolution comes up. Speciation helps explain a common ancestry. In our finch example, the two species of finches ultimately have a common ancestry even though they have now diverged, or branched off into a separate genetic line.
I have attached a picture of Charles Darwin’s First Tree of Life. Darwin knew from his observations that the variations in the animals he saw ultimately led to speciation, although he didn’t know the exact mechanisms. Today, his theories have been expanded upon with the advent of genetics to continue telling the extraordinary tale of evolutionary life on Planet Earth.
As I mentioned at the end of Lesson I, there is a price for admission. I am asking you to share these lessons with friends and family who you know don’t believe in evolution. 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.