Now that you know how the origin of life was a long, incremental, and random process, we can now begin to understand how evolution works. Evolution is the gradual appearance and disappearance of genes in whats referred to as a gene pool. A gene pool is the collection of all genes present in any and every individual of a single species. Lets use Darwin’s finches as our source of examples.
If you don’t know what Darwin’s finches are, it is a simple and observable example of how evolution acts on a species. A species of finch once exclusively inhabited the mainland and at some point migrated to several close islands off the coast. Each island had slightly different environments in terms of vegetation, animal life, and other factors. These birds, now in a completely different setting, had to “adapt” in order to survive on the island they now inhabit. The most obvious change was the birds’ beak shapes. On one island the main source of food was nuts and on another, small insects. Ill focus first on the nut eating birds. After many generations on this island the birds had developed larger, and tougher beaks in order to break through the hard shells of these nuts. What they don’t tell you in the biology books is that the birds whose beaks weren’t strong enough to break the shells starved and died. You cant pass on your genetic information to the next generation if you’re dead, so their genes were erased from the gene pool the moment they died. With the weak beak genes gone from collective pool, only hard beak genes remain. This repeated cycle is what causes change among species.
Cell division of the replication of genetic material which is used as the blueprints to create every cell in your body. However, though rare, mistakes in this replication do happen. These mistakes are called mutations. Mutations are random. One mutation might give a bird an extra toe, or an addition tail feather, or even a slightly bigger beak. For one of these finches on the nut island this mutation probably saved its life. If it hadn’t had this mutation for this abnormally large beak, it may not have been able to eat just like many others. Because his mutation allowed him to live, his genes for a larger beak remain in the pool and will be passed on to his offspring and so on and so on. DNA polymerase is the mistake checker during DNA replication and misses 1 mistake every 10 billion nucleotides. Evolution is these subtle changes in DNA sequence over thousands of years. The reason this is a theory of evolution and not fact is because the process is so slow we cannot measure it in real time, but finding remains of ancestral species from the past gives us a glimpse of what was and gives us a view of the progression of evolution.