Young earthers face an unsavory decision: either God continued supernatural creation of new species after He rested on the seventh day (which scripture does not close as it does the first six) or an accelerated evolution occurred following the flood.
The problem is that there are about 100 times more land dwelling species in existence than could have possibly fit on the ark (even by young-earther estimates.)
Furthermore, the fossil record, despite its apparent age, is said to reflect animals that died as result of the flood (but two of which were preserved on the ark). Thus many species (such as dinosaurs) existed at the time of the flood, were presumably preserved on the ark, but have become totally extinct since the flood, requiring even more species to appear since the flood in order to explain today’s vast biodiversity.
Either God continued to create species at a impressive rate after the flood (with no mention in scripture) or evolution works much better that Stephen Gould's wildest fantasy—with new species evolving faster than one per day—even faster considering that it had to cease with widespread human migration, since there are no reports of new (to be contrasted with undiscovered—which itself is rare) species popping up on a daily basis.
On the other hand, old-earthers have a view that takes scripture literally and, instead of proposing a form of super-evolution, actually explains what evolution cannot.
Old-earther’s (at least those with the day-age view) take scripture literally by reading the Hebrew word yôm as age. While today we have a rich vocabulary with choices such as day, era, age, epoch, period, etc., biblical Hebrew had an extremely constrained vocabulary—some estimate only around five thousand words, and the word yôm was heavily overloaded as the only word that existed for day, era, age, epoch etc.
So the old-earthers (day-agers) can take Genesis literally and put it to the scientific test.
At the highest level, the scientific prediction based on the bible is that:
- Life should appear in the order that the Genesis account gives (it does—vegetation and then in the oceans, birds, and finally mammals)
- New speciation should cease after God's final creation: man. Then God rested, ending the supernatural creation of species. This is what the fossil record indicates: no new species have appeared since man. On the contrary, and opposite to what evolution would teach, the only change in the number of species is a reduction due to those that are becoming extinct.
There are many great stresses on evolution. First, it is now known to have to have far less time than once thought explain the appearance of increasingly complex "simple" life (e.g., bacteria) from random eddies in the primordial ooze. The second stress is to explain the rapid introduction of new species during the Cambrian "explosion"—about one new species per year (~570 million years ago). The third is to explain reintroduction of species after they became extinct (such as horses). The fourth is to explain irreducible complexity (a component of an organism containing multiple parts that only functions when all parts are present—so the question is how did they all evolve at once). The fifth is to account for convergence, where the same design pattern is present in two or more species, even though they "evolved" in different environments and faced different environmental pressures. The sixth is the reversal of the evolutionary tree. Starting from a single node at the top, it should gradually branch and rebranch downward as new species are evolved, at most plateau-ing as resources are maxed out—but even then new species should appear. Instead the fossil record indicated and extremely rapid advance from nothing to huge biodiversity, then relatively little speciation for a long period, and now a shrinking of the width of the tree due to gradual extinction.
The day-age explanation: God created great numbers of species during the first six day-ages, sometimes recreating those that became extinct—all to groom the planet for human habitation. He reused effective design patterns. He "invented" irreducibly complex components. Then He created man and rested, ending the introduction of new species. Without a supernatural infusion of new species, the tree is shrinking as species, as they are prone to do, especially the complex ones, gradually become extinct.