It seems to me that paleolithic humans probably spent a heck of a lot of time carrying heavy stuff around. The spoils of a good hunt would have to be trekked back to camp. Gathered food, fire wood, rocks for building tools, supplies for building shelter, etc. would have to be carried back to camp. Children would have to be carried around before they learned to walk. Paleolithic humans were likely seasonally nomadic and it seems reasonable to assume that they dragged along some precious possessions (tools, spearheads, etc.) with them. There are theories of bipedalism that go as far as suggesting that we started walking on two legs specifically in order to be able to carry stuff.
From this, it seems like walking while bearing added weight would be naturally Paleo but oddly, I can't recall ever reading any Paleo fitness suggestions that included weighted walking. Walking a lot, yes. Lifting heavy stuff, yes. Walking while carrying heavy stuff, no.
I did a quick search for some research on the matter and found this study that concludes "Using a weighted vest can increase the metabolic costs, relative exercise intensity, and loading of the skeletal system during walking." Some other studies on the subject looked at usage by the elderly and found significant bone density benefits. I imagine the loading of the skeletal system would stimulate improvements in bone density for everyone but couldn't find specific data to back that up.
I'm not talking about those hand, wrist, and ankle weights but a safer and heavier load such as a weighted vest or properly fitted backpack. I found some stuff related to Navy SEAL training that suggests that humans can reasonably carry a load up to 40% of bodyweight. You can find 10-40 lb weighted vests on Amazon that are relatively streamlined and would be easy to slip on for a walk.
So what are your thoughts on this? Have you practiced any weighted walking? Have any of the big names in the Paleo world talked about this before (pro or con) and I missed it? Good idea, bad idea, or just useless?