The following is a pretty great description of what "Paleo" is all about. The below quote is entirely from my friend Trina, at www.paleonewbie.com. She sums it up much better than i could. The graphic, at the end, is entirely my poor attempt at putting the many faces of Paleo together in one place. I hope it helps.
"Paleo is shorthand for Paleolithic. The whole idea behind the Paleo lifestyle is that our bodies (specifically our genes) are programmed to function best when we eat only those foods that were available through the Paleolithic Era, which ended about 10,000 years ago. Any new foods that popped up after that on the Neolithic menu and later, are pretty much taboo on the Paleo plan today.
The 10,000-year cut-off is significant because that’s about when those early hunter-gatherers began turning into farmers and started planting and harvesting crops. Before that, eating grass seeds (grains) would have probably been a foreign concept to them. Likewise milking anything. And chances are legumes (beans) wouldn’t have been served at the dinner table because those need to be soaked and cooked to dilute the naturally occurring toxins. And most modern-day Paleo devotees believe the ancient ones didn’t go around digging up tubers either (like potatoes and yams – although there’s some heated debate about this one). Of course, the Paleo plan rules out anything processed, from margarine to Big Macs.
On the Paleo diet, you’re encouraged to eat meats, fish, vegetables, fruits, nuts, and eggs…basically whatever our distant relatives would have been able to scrounge up in the wilds to survive.
There’s some pretty good forensic evidence to back up the Paleo lifestyle based on the remains and artifacts of our predecessors. Compared to us modern humans today, paleontologists say our predecessors were taller, healthier, had larger brains, experienced less chronic disease, and had almost no tooth decay. Back in the day, the biggest threat to your life was cave lions or aggressive bands of humans rather than heart disease.
Along with the diet, most Paleo followers recommend exercising the whole body (mainly the short-burst kind of activity similar to what you’d get running around spearing a woolly mammoth) instead of spending endless hours on a treadmill.
Most Paleo practitioners also advocate getting regular sun exposure for the vitamin D, and a good 8 hours of shuteye each night."