As the body of human knowledge has increased, creationists advocating a literal interpretation of the Bible are required to devise ever more complex defenses. Like many debate subjects, it is easy to get caught up in complex details and miss the many simple and devastating debating points immediately available to anyone. For example, the Noah story involves the idea of a worldwide deluge that wiped out all life except the animals (representatives of literally all of the world's land dwelling "kinds") on one boat with its small crew of eight humans. Here are some obvious problems with the Noah story (with thanks to Robert J. Schadewald in Creation/Evolution and Mark Isaac in Talk Origins for many of these insights).

• There are literally thousands of freshwater species of fish for whom exposure to salt water would be fatal. A worldwide deluge would have wiped out freshwater environments by blending it with ocean water.
• Gen 8:11 says, "And the dove came in to him in the evening; and, lo, in her mouth was an olive leaf pluckt off..." Given that the world was covered for a very long time by raging waters, terrestrial vegetation would not have survived. There could be no living olive trees, and certainly none with leaves attached for the plucking.
• Predators don't exist in a one-to-one relationship with their prey.  For each predator, many individual prey animals have to exist in order to maintain a stable balance.  With only two of their prey species alive, how did these predators survive?
• Many species of germs are species-specific ("conspecific"). They can live only if they can find a host of just one species. They survive by hopping from host to host as each host specimen either dies or develops resistance. If only two of each "kind" were on the ark, then either the disease or the host species itself would have become extinct (since as one of the two animals died or became immune, it would have jumped to its mate, which would also have died or become immune). Yet, these species and their associated diseases are here today. This disease problem is especially applicable to humans: infectious life forms that can exist only in humans include measles, leprosy, typhus, typhoid fever, pneumococcal pneumonia, small pox, poliomyelitis, syphilis and gonorrhea. All of these would have to have been present in some or all of the handful of people on the ark and without killing them or being wiped out by their immune response.

Not only is this last point a problem for the literal interpretation of the Ark story, but it raises a question about the Creation story itself. Creationists seem committed to the idea that there was just one act of Creation. But if this is true, then diseases like small pox, poliomyelitis, syphilis and gonorrhea must have been created with Adam and Eve, before the Fall. If they were created as a result of the Fall, then there was a second act of Creation; if not, then these deadly diseases must have existed in the Garden Eden before Original Sin.  Even if the Creationist wants to argue that God fundamentally redesigned some earlier, friendly microorganism into these new organisms that can live only by feeding on humans, it stills leaves us with the creation of a new kind, regardless of whether it was created from nothing or from an earlier kind.  You either have an instance of a second creation act, or an instance of speciation occurring after the first creation act.