Just wondering. From The Smithsonian:
The 19th-century biologist Louis Dollo taught that evolution is irreversible; once a structure is lost, that pathway is closed forever. It’s a principle now known as Dollo’s law. But in analyzing the development of the ulnare, Vargas showed that it is, in fact, the re-emergence of the pisiform. “While the physical expression of a gene may be suppressed, it doesn’t mean the possibility of generating that structure has disappeared,” says Luis Chiappe, director of the Dinosaur Institute at the Natural History Museum of Los Angeles County. “The gene is still there, it’s just dormant.”
This isn’t the first time Dollo’s law has been challenged. Some mites have returned to their free-roaming ways after countless millennia living on animal hosts. And a tree frog from South America lost its lower teeth only to re-evolve them after 200 million years. Within the human embryo, there is similar potential. Perhaps the very bone you are sitting on, your coccyx, is ready to re-evolve a tail at some future moment when humans might need it again to hang from trees.
Dollo’s “law” is nonsense. But here’s the main problem: Assuming that all this is correct (and it isn’t my purpose to cast doubt on it), unless we have a complete, detailed history of every facet of evolution, how would we know that any evolution occurred?
That is, we cannot then use patterns based on laws, because they apparently don’t exist. So to be sure that any evolution occurred, we would need the same sort of documentary historical evidence that we would need for a historic battle. Thoughts? – O’Leary for News