I realize that “DaveScot says something incredibly boneheaded” is about as newsworthy as “dog bites man”, “Pope is Catholic”, and “Hollywood remake not as good as original”, but this time I couldn’t resist.
Every time someone tries to demonstrate evolution by pointing to one of the numerous instances when new species have arisen through evolution, e.g., fruit flies speciating into two distinct species in the lab, you can bet that the creationists will say, “but they’re still fruit flies!” This raises the question of just how much change creationists will accept as microevolution.
DaveScot provides a partial answer at Chez Dembski. In a post criticizing an article demonstrating evolution from one type of photosynthesis to another in certain plants, he writes:
C3 photosynthesis is used by agronomically important grasses such as rice and wheat while C4 is used by agronomically important grasses such as corn. The difference is that C4 grasses can survive in a
more aridhotter environment. The similarity is they’re all still grasses. Where’s the macroevolution in that?
Now we know: a single species evolving into rice, wheat, and corn (maize) is still just microevolution. Since he calls them all “grasses”, perhaps we can add suburban lawns to the list.
In the meantime we concede that microevolution happens. We’re interested in how microevolution like this adds up to macroevolution of novel cell types, tissue types, organs, and body plans. I’m sure that how rice evolves into corn is an interesting bit of esoteric trivia for botanists but the debate – and there is most certainly a debate – is about how bacteria evolve into rice.
Rice and corn are both in the order Poales (which also contains pineapples). I realize it’s tricky to compare plant clades to animal ones, but humans are in the order Primates, which includes all apes, monkeys, and lemurs. If DaveScot accepts diversification into rice and corn as due to microevolution, then he should have no problem with diversification into gorillas, chimps, and humans as microevolution as well.
Bacteria and rice, to use his example, are in different kingdoms. Bacteria are prokaryotes, while rice is a eukaryote. So apparently by “macroevolution” DaveScot means “the kind of differences that take 1.6 billion years or more to accumulate”.