Here's a prime example: the vermiform appendix. There's no selective pressure for or against this vestigial process, yet we still have it. Perhaps if we weren't so medically advanced as a species, then there would be the selective pressure of ruptured appendices causing septicaemia and death in people before reproductive age; however appendicitis is hardly a selective pressure today. Things like this may eventually regress or entirely disappear, but until having an appendix negatively affects a person's genetic fitness, it's regression would simply be due to a serious of random mutations (though I don't think the human race is going to survive much longer, evolutionarily speaking
).
Cheers,
Ryan
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