Quote from Gabfly1:
In his book that I mentioned earlier, Dawkins also talks about "unintelligent design," as he refers to it. Specifically, there are numerous design inefficiencies in various species that are clearly the result of incremental tweaking that stem from plodding natural selection over time rather than a divine grand design. Whereas the "marginal cost," so to speak of the minute incremental changes over time do not otherwise affect survival, they can become peculiar in the fullness of time. However, natural selection (survival) would not tolerate major-overhaul-type back-to-the-drawing-board redesigns. And so, there they are. Although these inefficiencies may not affect survival, such imperfections do not suggest a divine creator, but rather the result of bottom-up tweaking that is characteristic of natural selection. Examples include the oddly "designed" laryngeal nerve, the vas deferens, the eye, and so on. Also, by way of example, whales, which had initially crossed over to land in a prior form and then reverted back to water, have tiny bones buried deep inside them which are remnants of the pelvic girdle and hind legs of their long-gone walking ancestors. Again, bottom-up tweaking over time consistent with natural selection, rather than top-down grand (and divine) design.