It is a two pronged critique. Part of the argument is just based on numbers. It goes something like this:
- By most estimates, Noah’s ark could have carried at most 30,000 pairs of land animals.
- At least 5 million species are alive today, and an additional 2 million existed after the flood, but have since become extinct. (The fossil record indicates a total of about 500 million species have existed throughout the history of the planet.)
- Exacerbating the problem, we are told that shortly after the flood certain species that were on the ark became extinct, such as the dinosaurs.
- Taken all together, we see that somewhere around ten thousand species that survived on Noah’s ark, and the extinction shortly thereafter, would have to evolve into millions of species in the span of a couple thousand years, a rate that makes the mind reel.
Of course, God could have just created the new species, but there is no mention of that in the Bible. As far as scripture reveals, all God’s creation of new kinds ended at the end of day 6, which obviously was well before the flood.
Another problem that Ross and Archer (and others) point out is that of carnivores. The usual argument is that there was no death of any kind, not even animal death, (Hey there Mr. Elephant, don’t step on that ant!) prior to the fall (which, again, means after God had rested from his acts of creation, inasmuch as they are revealed). No animal death means no carnivores. Carnivores are designed by God to hunt, kill, and eat. If God put Polar Bears on earth but had them eating plants, they would have to be very different from Polar Bears as we know them today—their metabolism and body type render them incapable of surviving by grazing. In effect, all the carnivores would have had to evolve rapidly (in the timescale of hundreds of years) after the fall.
So Ross makes, in my opinion, a good point. The young-earthers (among which I count almost all of my friends, except the other pointed-headed scientists like myself) need a more efficient evolutionary process than the naturalists would dare to hope for. Go figure.