The theory of evolution asserts that all living organisms are related, they descended from common ancestor(s), and the variations are explained by natural processes such as natural selection and genetic mutations. Scientists cite several evidences for evolution such as:
- Comparative anatomy: the study of differences and similarities between living things
- Embryology and development: how creatures develop before being born or hatching from an egg
- Fossil record
- DNA similarities: the molecules that carry the codes with the characteristics of living things
For example, if we compare hippos with whales, we find the above four pieces of evidence. First, the anatomy of a whale and a hippo shows that both have smooth skin, lungs, internal testicles, etc. Second, the development stages of both embryos look similar. Third, there are fossils indicating transitional animals that are similar to whales, yet with legs as hippos. Fourth, the DNAs of both hippos and whales are closely similar. All this evidence points to a common ancestor between whales and hippos.
While all of the above is true, the evidence can also support common design and intelligent design as much as common ancestry and evolution.
Take for instance cars. If we apply the same evidence for a BMW and a Toyota, we would reach the conclusion that both brands descend from a common ancestor car, but they obviously don’t!
When considering comparative anatomy, both BMWs and Toyotas have 4 wheels, an engine, doors, windshield and a trunk.
When considering development, the production of both a BMW and a Toyota is similar.
When considering the scrap metal of both a BMW and a Toyota, they look the same, as we can find scrap wheels, engines, and steering wheels.
Finally, when considering structural similarities, both cars are built from the same components.
There are two objections to this analogy by evolution supporters though:
We have seen cars being designed before, so when we see a car on the street, we can draw an inference of design based on prior observation. But that doesn’t apply to living organisms because we haven’t seen anyone create them.
Answer to Objection 1:
Well, recognizing design doesn’t really necessitate that you have seen the designer in action or have a preceding observation of the production process. Scientists like Newton and Kepler have recognized design in the way planets are orbiting without having seen the designer. When you see writing on the sand along the seashore, it is reasonable to assume that someone has written it, not ocean waves, even if you haven’t any person writing on sand before.
The car analogy is false, because cars don’t have mechanisms to evolve like living organisms do. Living organisms have mechanisms to evolve, which are mutations and natural selection. These mechanisms explain the vast variation in living things that we have today.
Answer to Objection 2:
Both natural selection and mutations are not sufficient to explain biodiversity. Natural selection is a process where the fit-enough for the surrounding natural conditions survives. Therefore, the characteristics that nature selects already exist in the gene pool. Natural selection cannot add any new characteristic to the gene pool. It just selects from existing characteristics, i.e., it’s a process of subtraction. Mutations are mostly harmful or neutral. They are also as random as ocean waves. If you find it hard to believe that trillions of ocean waves can eventually produce an essay on the sand of the seashore, then you might as well doubt that mutations can lead to DNA or biodiversity.