The original question was: I heard on Discovery channel that the dewclaws that some dogs have are vestigial. I did research but can’t find a clear answer to why this is not so. Can you explain this, because especially dogs sometimes have dewclaws on their hind legs which serve no purpose because they don’t hit the ground?
A dewclaw is a claw on the inner side of the leg, above the main part of the foot, so it does not rest on the ground or take any weight when the dog is standing or walking. In many dog breeds it is attached to the leg bones by muscle and tendons, and is therefore a functional structure. When the dog runs it can make contact with the ground, and the dog uses it when making quick turns. Even if the claw does not make contact with the ground, or take any weight, the dog can use it to scratch itself to remove irritants from around eyes, ears and in its fur. In some dogs it is robust enough to be used to help manipulate objects, such as bones and sticks.
Some dog breeds have dewclaws on their rear legs as well as the front legs. Some large breeds e.g. Rottweiler, German Shepherd, can have two or three “toes/nails” on the rear dewclaw, and are these are usually unattached by bone. These dewclaws can be used for grooming, scratching and clasping, and even in play or hunting.
Not all dog breeds have dewclaws. Our domestic breeds are often quite removed and different from wild dogs due to selective breeding.
In some breeds the dewclaw is present but lacks the muscle and tendons needed to make it useful, and in these cases it could be called “vestigial”. However, this is not evidence for evolution. It just means that a functional claw has become degenerate and lost part of its structure, and is no longer useful. In other words, it is a reminder that, like all living things, dogs are going downhill, not evolving upwards.
For more on vestigial organs see the Creation Research article Vestigial Organs. PDF here