The types of bird beaks, the colors of moths, leg sizes, etc. Each type and length of beak a finch can have is already in the gene pool and adaptive mechanisms of finches.
Creationists have always agreed that there is variation within species.
A human generation takes about 20 years from birth to parenthood.
They say it took tens of thousands of generations to form man from a common ancestor with the ape, from populations of only hundreds or thousands. A new generation of bacteria grows in as short as 12 minutes or up to 24 hours or more, depending on the type of bacteria and the environment, but typically 20 minutes to a few hours.
The top problems with evolution explained using scientific evidence against evolution.
In the creation evolution controversy, it is clear not only that the theory of evolution is wrong, the theory of evolution is false, but that the theory of evolution is a the real part.
They wrote that "forward experimental evolution can often be completely reversed with these populations". Mutations that result in a gain of novel information have not been observed.
Thus all the right mutations (and none of the destructive ones) must happen at the same time by pure chance. To illustrate just how hopeless it is, imagine this: on the ground are all the materials needed to build a house (nails, boards, shingles, windows, etc.).
Fruit flies are much more complex than already complex single-cell bacteria.
Scientists like to study them because a generation (from egg to adult) takes only 9 days. Here is how the imaginary part is supposed to happen: On rare occasions a mutation in DNA improves a creature's ability to survive, so it is more likely to reproduce (natural selection).
Only mutations in the reproductive (germ) cells of an animal or plant would be passed on.
Mutations in the eye or skin of an animal would not matter.