Quote:
Originally posted by DA Morgan:
Simply put ... if humans were "designed" then explain why human males have nipples?
A classic example. Gould wrote an article on this topic - and the related question of why females have clitorises - which he really wanted to title "Tits and Clits". His editors insisted that he change it, so he compromised with "Male Nipples and Clitoral Ripples".

An even better example: all terrestrial tetrapods are prone to choking. We have one hole (the pharynx) through which both food and air must pass before entering their separate tracts. It's vital that food must not enter the respiratory tract, and yet every time we swallow, we shove food right past the opening to it. That's a STUPID design. Yes, there is a flap of cartilage (the epiglottis) that closes the digestive tract off during those brief moments, but it doesn't work perfectly; people (and other terrestrial tetrapods) choke to death all the time. And anyway it wouldn't be necessary if only an intelligent design had been adopted from the outset. Insects have a much more intelligent design: numerous holes along the sides of their bodies (spiracles) for their respiratory system and a separate hole (the mouth) for their digestive system. There is no need for the two systems to intersect.
So why do we have this design flaw? Simply put, because our ancestors had it. We evolved from lancelet-like animals that used a "pharyngeal basket" for both digestion and respiration. We are stuck with a fundamental body plan that has the two systems in close proximity. Darwinian natural selection might get rid of this design if there were an alternative design to compete against it, but few such alternatives have happened to crop up.
Actually, there is one very instructive case where a group of mammals did happen upon an alternative body plan in which the digestive and respiratory systems have distinct, non-intersecting pathways. What's more, they have adopted a lifestyle that actually requires this separation, allowing them to catch food and eat it underwater without the danger of drowning. These are the cetaceans. Whales and dolphins can't breathe through their mouths because their mouth does not lead to their lungs. And, of course, they can't choke on food.
It's interesting to speculate about the relationship between the adaptation (blowholes separated from the digestive tract) and the aquatic lifestyle. Which encouraged which? Which came first? Even better is the fact that the early evolution of whales is exquisitely documented in the fossil record - one of the best, most complete, and most dramatic collections of transitional fossils we have.
A couple of excellent web sites:
http://www-personal.umich.edu/~gingeric/PDGwhales/Whales.htm
http://www.neoucom.edu/DEPTS/ANAT/Thewissen/whale_origins/index.html

Can you tell that I really get excited about this topic?
I simply love examples of stupid design in nature; they're so instructive. Even better is to find examples of stupid design where different groups of organisms use different adaptations to solve the same stupid problems imposed by their common evolutionary heritage.

Of course, the example I am most intimately familiar with, after recent back troubles: anybody who believes in intelligent design has obviously never endured the utterly pointless agony of lower back pain. Thanks a lot, great designer!