Circumcised Men Are 5X As Likely To Become Impotent 570

Humans do have vestiges, and we do have features which are totally functionless. Note that these are not the same thing. Vestiges can be functionless, but they don't have to be. Charles Darwin himself stressed that vestigial structures can have function in On the Origin of Species:

"Rudimentary organs, on the other hand, are either quite useless, such as teeth which never cut through the gums, or *almost useless*, such as the wings of an ostrich, which serve merely as sails." (page 603, emphasis mine)

He also stressed that these structures can be co-opted for other functions:

"... an organ rendered, during changed habits of life, useless or injurious for one purpose, might easily be modified and used for another purpose." (page 603)

So an organ can be considered vestigial if it is homologous to an organ in an ancestral species, and its original function has been diminished to nothing (or almost nothing). Even if it serves a different function today, it can be considered vestigial if the *original* function is absent or diminished. The Encyclopedia of Evolution (2002) states:

"Vestigial organs and structures (also called vestigial, rudiments, or remnants) are reduced body parts or organs, often without visible function in the derived bearers, that were fully developed and functioning in earlier members of that phylogenetic lineage. These structures, sometimes described as atrophied or degenerate, are usually small in comparison with their relative size in ancestral generations or in closely related species. ... vestigial structures may have acquired new, less obvious functions that differ from the original ones. Hence, a vestigium should not generally be considered without function, or only with respect to its ancestral, adult roles."

So in this sense, foreskin can be both functional AND vestigial.

I don't really understand your "love linked" argument. Whether or not a feature is "love linked" really has nothing to do with whether or not that feature is vestigial. Male nipples are certainly an example of jury-rigged design, if not truly vestigial. Witch's milk is a great example of diminished function in that the original function of nipples is to deliver milk from the mammary glands, and in men this function is either diminished or completely absent. And actually, since most males do not produce milk at any stage of their life or development, Witch's Milk could be considered more of an atavism than a diminished function. In most males, nipples are entirely functionless.

The appendix is another great example of a vestige. It is obviously homologous to the tip of the caecum found in other mammals. In other mammals, it serves the function of digesting plant material. For humans, it is completely functionless in that regard. Scientists have been suggesting different possible functions for the appendix for decades upon decades. For instance, because the appendix contains healthy bacteria that aid in the digestion of food (the same bacteria that you find in the intestine), it was once thought that, by introducing the immune system to these bacteria during fetal development, the appendix serves an important gastrointestinal immune function. However, because these bacteria are the same bacteria that are found in the intestine, it turns out that the appendix is truly useless in this regard as well. This has been confirmed experimentally, as many people are known to have been born without an appendix at all, and their gastrointestinal and immune systems are just fine.