The crux of evolution is passing a template to the next generation.

Time is more of a requirement in seeing the results. Given enough time and you get more then enough variety. Each generation can have a change, seeing those results withou DNA testing can take many generations to see.

The age of the Earth is a geological and/or astronomical area of endeavour. Mind you the various fields of science can be used to calibrate and test the other fields. That the age of the Earth is ample enough for Evolution from inanimate to cell to multicellullar life is apparent within the fossil record. That age of sediments can be approximately dated by matching the fossils within them with other such fossil sites around the world.

Scientists get a perverse joy in tearing down theories, even their own if they can find a more elegant solution that fits the data.