"If you tried to teach a highly intelligent 19th Century adult how to use a laptop, it would be like teaching a dog to dance . . . ."

To the contrary, I suspect that Charles Babbage or Pascal would take to the modern computer like a duck to water. I also suspect that intellectuals of almost any century (at least postdating written language and invention of the zero) could and would learn to use a laptop just as easily as any intelligent modern person.

How Boasian to think that our capacity to learn is a function of our "familiarity", i.e. environment.

Even "primitive" peoples have been shown to adopt modern technology quite readily.