Well, I don't mean a literal body, of course, but maybe I do. I was wondering, since we're trying to replicate the way Grok lived day-to-day, if that form of primal exercise has ever been looked at... dragging heavy objects in the way he might have had to drag a moose or an elk long distances.
One way to accomplish it would be putting your kids, wife, friends (or any combination thereof) on a big tarp and rigging a harness to drag them around the back yard. It seems quite a few large muscle groups would come into play.
If you're holed up in your home gym over the winter, maybe accomplishing something more isometric with a rope and an innertube from a truck?