Mutation and natural selection.
Easy to say but impossible to prove.
Directly observed. Can't do much better than that. Would you like to learn about some examples?
How did "mutation and natural selection" allow mammals to (allegedly) descend from fish, for example?
Sure. Some sorts of fish, including those still surviving, have the same bones as mammalian limb bones. Lungs actually evolved in fish before bladders, and in Rhipidestian fish, were used to breath air. There is an extensive fossil record, showing the transition from lobed fin fish to fish with limbs for walking on the bottom of shallow water, to fish that were capable of walking on land, to land-based tetrapods. It's one of the sequences that YEC Dr. Kurt Wise admits is "very good evidence for macroevolutionary theory."
One, and the surviving members of that group of fish are genetically closer to us than they are to other fish.
Lungfish (Dipnoi) are widely recognized as the closest living relatives of tetrapods (four-limbed vertebrates). This relationship is supported by both fossil evidence and molecular data. While coelacanths were previously considered strong contenders, recent studies increasingly favor lungfish as the sister group to tetrapods.
How about that? I'd be pleased to see your evidence that any step in the evolution of humans from fish could not have happened by mutation and natural selection. What do you have?
The truth is, you can't even demonstrate that such a transition was the result of a natural process,
As Dr. Wise admits, the fossil record is very good evidence for it. And of course, DNA analysis shows that mutation and natural selection were indeed behind it, as does observed evolution we see today.