Evolution.

You don't know that for a fact, because it's not true. The footprint you've seen isn't a human foot. It doesn't even look like a footprint!You're misinformed, I hate to tell you. There are no instances of human and dinosaur co-habitation because dinosaurs died out 65 million years before the dawn of man.

There's a number of Neanderthal skeletons, and the only one with arthritis are the ones that were old when they died. How could arthritis result in a massivly larger brain than Homo sapiens? When was the last time you saw arthritis make someone's brain larger? Apes, because we're still apes. We evolved from the ancestor of apes, which was an ape.Apes aren't monkeys. Monkeys have tails, for instance. The extra chromosomes. It's the same reason you can't mate with a gorilla. Can they mate with people of other races? There's your answer, then. If they can mate with humans, they're humans. If Asian people stopped being able to mate with anybody but Asians, they'd be a new species.We gave you the definition of species. Is there are reason you refuse to apply it?

If they wanted to do that, they wouldn't be creationists.You're talking to a group of people who believe that ignoring what's laid out plain in front of them is a valid, Scripturally-supported methodology.The best you can do is beat them over the head with it. Sad but true. If you don't want to repeat the same thing over and over and over, you're in the wrong kind of argument. Take up Mock Trial.

I think I speak for the field of evolution when I say that currently there are a number of speculations about the origin of life, and that a bacteria is significatly more complex and evolved than the first lifeform likely was. (If you have an idea that bacteria represent the simplest form of life, that's just not true. Like everything else alive today they're the succesful product of a billion years of evolution.)There's not much known about the first life. Researchers are working hard on trying to duplicate the events that they believe first led to life, but even if they do, that's not proof that it happened that way. the problem is that there are is no fossil record about the first living thing, because it was too small and too fragile to fossilize.But there's a vast weight of evidence that all living things decended from a common ancestor. We make inferences and speculation about what that common ancestor was like, but we believe nothing about it because we don't have any fossils of it. Make sense?The origin of life is a contentious issue, but luckily it's not one that pertains to the rest of the question of evolution. Evolution works whether the first living thing came to be by accident, or by design, or by magic.