Does it matter whether the larvae of one fruit fly species have hairy backs while those of another are smooth? Well, for scientists who believe both species descended from the same ancestor population, it could perhaps be taken as an example of evolution in action. The genetic causes for these particular differences, however, clearly show that no Darwinian processes were involved.

More than 80 varieties of fish, amphibian, and reptile mothers are able to lay eggs that have not been fertilized and yet produce offspring. In a process called "parthenogenesis," these eggs hatch little clones of the mother, which in turn lay clone eggs themselves. Could this remarkable mode of unisexual reproduction have evolved?

What if there were not a fast or effective way to get rid of sewage waste? The world would be a pretty disgusting place.

If Charles Darwin could see today's best examples of evolution, would he be elated or depressed?

An animal wouldn't grow larger than an insect without specialized equipment designed to transport oxygen to and carbon dioxide from cells deep inside its body. Fortunately, thousands of different animal kinds have been outfitted with tiny machines called hemoglobins that directly and specifically interact with individual oxygen molecules, making larger body sizes possible.