Who invented chewing gum and why?

Ron, a friend of mine, threw this question at me as kind of a sidelong joke in an e-mail he sent me. But it was a question I didn't know the answer to so I did a bit of research and wah-lah, here's a website on the invention of chewing gum. (gods, I love the internet!)

It turns out that who the original inventors are is actually a toss up between the Greeks and the Mayans. I'm tempted to give it to the Mayans since the Greeks claim so much already, but I do dig the Greeks... No matter. The true originator may have been Ung, the greatest masticator of the cave-people. She began with tree bark, but it didn't have the great appeal other massive masticators had with their inventions.

But as to the why.... On my darling web, there are numerous sites explaining why chewing gum is banned from schools, why chewing gum is bad or good for your health, why people chew gum in airplanes, but nothing on why chewing gum was originally invented. So, without further ado, here is the completely made-up but totally true Hyena explanation as to why chewing gum was invented...

Chewing gum was invented as jaw calisthenics. That's right folks. Ung, the original inventor of chewing gum, noticed how members of her tribe kept being afflicted with "huuuuuuuoooo!" which translates almost literally to, "broken jaw due to extremely tough meat of saber tooth tiger." Later, she discovered that most of the broken jaws had to do more with the fact that her fellow tribe mates were trying to eat the meat before the beast had actually been captured. And that's when she invented the spear.