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“…there’s just way too much goofy crud in our genome that can get screwed up at the drop of a hat…”

Natural selection favors the easily adaptable.

Call Tony Curtis.

Clearly an example of Intelligent Design at work.

there are things called teratomas, where a particular kind of cancer recapitulates a developmental program and builds tissues, things like skin with hair or teeth or chunks of muscle and bone and gland, but those aren’t this well organized. They tend not to produce complete organs, but partially differentiated sheets and lumps. Another possibility is fetus in fetu, where a fragment of the very early embryo is isolated and begins its own independent pattern of normal development, and then is engulfed by the larger and faster growing sibling embryo. Sometimes people late in life will be surprised to learn that there is a partially developed twin imbedded deep in their body. There is no question in any of these cases, however, that the tissue is not an autonomous individual. It is a piece of human-derived tissue that has executed part of the program of cell:cell interactions and induction that these kinds of cells are capable of doing.

Some years ago I read an absolutely wonderful book called MUTANTS by evolutionary biologist Armand LeRoi. A detailed and not too technical (but still in-depth) look at all the weird ways our genetic program can go “off kilter”. I highly recommend it if you really want to understand what’s going on here at more than a superficial level. I feel the book also essentially gives a great riposte (though I don’t think this was its intent) to folks who fatuously claim we’re perfectly designed beings – there’s just way too much goofy crud in our genome that can get screwed up at the drop of a hat for it all to have been put in there deliberately.