One of the big groups trying to keep people scared of evolution is known as the "intelligent design" movement. People like "biochemist" (in quotes because he brings shame to his field) Michael Behe claim that because the small features (such as a flagella or cilia) of microorganisms are actually quite complex and because the parts of those features don't "do" anything by themselves they could not have evolved by natural selection.
But the thing is sometimes things just mutate. And sometimes the function of a structure is lost over time. Evolution is not a straight line. It meanders and wobbles and every now and then a form evolves that happens to be better suited to a particular niche.
And sometimes in nature you find a species or a structure that really...just seems dumb. I may have written about this before but take the human lower back. People have bad backs because we evolved upright walking out of four-limbed locomotion. The vast majority of human anatomy didn't change and so pressure is applied in all kinds of weird and awkward ways on our lower back muscles. Doesn't seem so intelligent.
So earlier this week I read about another great example. As you may have noticed ants have really tiny waists. As a result they need to subsist on liquids. Most ant species get this liquid nutrient from the predigested food of their larvae. This is already a weird situation. They need their babies to chew up their food for them. It doesn't seem particularly intelligent to design an animal that can't eat by itself.
Now even weirder and probably dumber is the Dracula ant. This particular species diverged from other ants about 100 million years ago and does not feed in the same way. Instead they feed on blood. But not, like you might expect, the blood of other animals. It feeds on the blood of...wait for it...the larvae. The adult ants actually have to slice into the larval ants and drink their blood. How is this a good idea? It's not. But it's an example of natural selection at work. A problem needed to be solved and the genes involved mutated so that these particular animals would feed in this bizarre and, frankly, somewhat dumb manner. Now if adults feeding on the blood of babies isn't a great argument against intelligent design, I'm not sure what is.
Thanks to Myrmecos and Ugly Overload for the info: