h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Did you know that guinea pigs were first domesticated in the Andes 4500 years ago?
This has always confused me. What were the people up to? How bad at hunter-gathering do you have to be before chasing small balls of fur with a top speed of 1.5 mph becomes so difficult you have to domesticate them in order to eat them? I'd have thought, as wild animals go, the guinea pig came pretty much pre-domesticated.
Perhaps the guinea pigs of 3000 BC were very different from the ones of today. Huge, six-foot carnivorous beasts. Sabre-toothed.
Perhaps they looked like this:


Oh no, that's a fish. Damn. How long before we get little pictures of guinea pigs on this thing?

Was there nothing that was what we now consider to be normal-sized in ancient times? There are cave drawings of blokes chasing armadilloes the size of cars and bones of sloths as tall as a bus. Maybe there were once some really huge people, as tall as trees. That would be nice. Anyone know where I can mock up a skeleton or two?

Or maybe the people drawing the pictures either had no sense of scale, or were really really small.

Maybe there was an element of "you should have seen the one that got away" to it when the hunters of ancient times returned to their hungry tribe dragging tiny little carcasses of distinctly non-fierce creatures. Perhaps the recent research indicating that the mastodon's bite was relatively weak will eventually reveal that all the skulls found so far are mock-ups by dejected palaeolithic huntsmen more into sculpture than painting.