Nomads and Human Migration- I mean ancient.

You know what, I think I might just regret I ever thought history would be boring. Ah, typical stereotyping.

This lesson we learnt about ancient human migration and watched more spooky skeletal movies. Just kidding- but we still watched lots about how archaeologists uncover these ancient artifacts to prove that their theories are correct. Still, it may be proved wrong one day. Can it?
Nomads are people who "think with their stomachs", that's how Mr. Smeed put it. That is, they would travel no matter how far, as long as they have food. So back then, guess the only purpose for the natives was to hunt and work mainly for food.
Unless I wasn't paying attention, which I (think I) was, I now have a question about why people bothered to move at all. I mean, if people managed to live even staying in Africa (which there WERE some people who did), why did they even bother to travel anywhere else? Sure, they follow the food, but if there was food in Africa, why take the hard way to get it? Is it because they wanted excitement? Possibly they wanted the particular game that moved in that particular route? Then if everyone had, would that mean we'd all be Negroids today? (A note: Negroids are native, or native-related people to Africa, Caucasoid are the same to Europe and Middle East, Mongoloids to Asia, Australoid for Australasia. It only applies if you're of that blood, however distant as long as you're "Aboriginal")
Guess they wouldn't be Nomadic anymore if they don't move, though.
Then we started talking about "ice land bridges". This means the connection, the portal between the Old World and the New World. In simpler terms (starting to sound like math), that would be the Bering Strait, Beringia. People would only be able to cross when it was all frozen, which complicated things by a mile in the least. This is called a legendary Ice Age, when for some or no apparent reason, everything in the Northern Hemisphere freezes up into glaciers. During our last one, it blanketed North America nice and warm (or would it be cold?). Only over Northern Hemisphere, though. Why would that be? Would it be a scientific reason, a philosophical one; a metaphysical one; a religious one?
Anyway, Ice Ages rival global warming (go for it, Ice Age), and it decreases the sea level because most of the water just gets stored in the ice. This very Ice Age 17,000 years ago caused the ocean to drop, uncovering new land that connected Siberia to Alaska. This was 18,000 years ago. As time progressed, though, the Ice Age slowly began to end, the water slowly filling back Beringia. By 10,000-9,000 years ago or so, the land bridge disappeared. People had to have come before that time, if the theory is correct, because otherwise how would they have come to the New World?
A lot of people seem to wonder how the land just disappeared. Poof! It makes me confused, because I thought it "disappeared" because the ocean rose back to its original elevation. I mean, before the Ice Age, wasn't the land bridge invisible, covered by the sea like it is now? (Guess people will have to keep making more theories to answer all this.)
Here's my bet, if we just dried up the Pacific Ocean, we would find the ocean floor beneath (after a LOT of drying up), right? That might just as well be a "land bridge" too. So what I'm trying to say, is that may have applied just as easily to Beringia. Unless, of course, some person finds proof that Beringia Land Bridge has ALWAYS been there even before the Ice Age.

I'm sorry if my post seems a bit disorganized (which it is).