Incidentally, science is very similar to a crossword puzzle. When first filling out a crossword puzzle, you start tentatively, with a hypothesis, and see where it takes you. The spaces that you know help to unravel the answers to the blank spaces, in much the same way that theories in geology, like that of continental drift, helped explain how ancient species with a common ancestor could be found in distant places like Africa and South America. (The answer? The two continents were once joined!) In a sense, then, geology can inform biology, and cosmology can inform biology, and vice versa.
The questions and the size of the boxes, of course, represent the evidence. We will know how many letters and the meaning of the word in question in order to best figure out what fills the spaces, just as in science we know that evolution predicts that life would evolve in a manner so that bacteria preceded fish and fish preceded mammals. (And just as we know that the word “Evolution” is the best fit in the crossword depicted above at 4 down because it has the right number of letters and answers the clue in the best way.)
Creationism and Intelligent Design, on the other hand, don’t play by the rules. They bend and distort facts to make them fit religious dogma, ignoring the evidence, clues, and size of the boxes to fit their preconceived notions into a framework that may resemble science but which is actually quite the opposite. Where they do make testable claims, the creationists and Intelligent Design proponents find themselves thoroughly refuted. (When Behe, for instance, proposes the bacterial flagellum as irreducibly complex when research totally contradicts him. Or when creationists argue that the flood was caused by a canopy of water suspended in the atmosphere–which would have made the temperature of Earth intensely hot and unsuitable for human life.) For the most part, though, the creationists don’t even write in the boxes of the crossword puzzle, instead opting to write out “God” on the margins–a proposal that is hardly testable, not warranted by any of the clues listed or any evidence, and which is incapable of being supported by all of our other knowledge as it is entirely removed from the empirical, scientific realm.
For more on science as a kind of complex, ever-changing crossword puzzle, I highly recommend reading the works of Susan Haack, particularly her books Defending Science and Evidence and Inquiry.