The science of genetics has made huge progress with the Human Genome Project. This project was initiated in 1990.
These studies have started to reveal details about genes showing that mutations often cause dysfunction compared to the original function : for example, tortoise shell cats have a patterning gene that inhibits the production of black pigment. The gene is called agouti. When this inhibitor is switched off, the result is black cats which have no tortoise shell pattern. This occurs by a single mutation.
What I realized was that evolution at the genetic level involves loss of information in the genetic code. There is a move from function to dysfunction. But at the physical body level there is either modification or loss of parts.