my hardwood floors are original to the house. the original owners of the house are the people we bought it from. (well the kids of the original owners) so its probably more than 50 years old.
the individual boards are not cracked. there are cracks between the boards. as far as scratches go its hard to do. the dogs don't leave marks with their claws. BUT this floor has not been refinished in 20 or more years and there is next to nothing left of the finish