Being lactose intolerant, you’re like the majority of mankind. That is, one of the normal ones.
B) No. The lactose tolerant fifth of humanity are mutants.
Damn Celestials - worst superpower ever. Except for maybe Hector Rendoza’s.
By way of comparison we share around 98.7% of our DNA with bonobos. All modern humans are homo sapiens sapiens, which emerged about 200,000 years ago, give or take. If, by cavemen, you mean those chaps in Europe who lived in caves and had the idea of art, which stuck around, was about 40,000 years ago - they’re us, no question.
If by caveman you mean our extinct cousins the Neanderthals, commonly but inaccurately depicted as brutish cavemen, the answer is (preliminarily) about 99.7%. Definitely enough to conceivably interbreed, although whether we did or not is debated.
We who sit at computer terminals all day (and/or all night) on the Straight Dope Message Board are, all of us, on our way to becoming atavisms.
Thanks for the cites.
I now see that we have to make room for that Denisova female and her people, which the Homo sapiens and Neanderthals apparently had to also as they all slept around in a particularly lively cave.