Dogs and pigs are cheaper than monkeys and apes, and do not have quite as
strong support from the animal rights movement. Rats and mice are cheaper
still and have even less of a following. They also have shorter generation
times (especially important in studying genetics), take up less space, and
are easier to care for. All of these are eutherian mammals, sharing a
common ancestor as recently as the Cretaceous. All are much better models
for humans than reptiles, birds, amphibians, fish, or invertebrates.
The suggestion that the kinds were created by God at once, using similar
patterns, does not satisfy me because it does not account for the
transitions in the fossil record nor the consistent pattern of
non-functional similarity. Even though they all do the same thing, the 18S
genes of oysters are more similar to each other than any is to scallop 18S
genes, but those are more similar than snail 18S genes, which are more
similar than brachiopod 18S genes, which are more similar than flatworm 18S
genes.... Likewise, non-functioning features of the DNA are more similar
in closer relatives, such as pseudogenes or gene rearrangements.