What I can't understand are the assumptions about "fat" and "oil" with respect to primitive hunter-gatherers.
True, Atkins and others advocate more fat ("eating fat does not produce fat, it burns fat") but that is not the same conversation.
There is also the excellent chapter in "The Zone" called something like "The Hormonal Effects of Food" which is well worth reading.
But, the fact is, until the advent of agriculture a couple of hundred generations ago, and, more dramatically, the explosion of processed foods and refined carbohydrates in the last 3 generations, "food" was generally something natural and raw. Has the evolution of the human digestive system kept up with these changes? Evidence suggests not, at least for a significant portion of the population.
But, back to fat: first off, the vast bulk of ancient diets was plant material. The romantic notion of hearty he-men dragging home loads of meat every day is probably little more than a myth. And even when someone was lucky enough to make a kill, very few animals in the wild are carrying much body fat at all, with the exception of mammals in late summer or autumn in the harsher climates.
And "oils" were pretty much unknown until agriculture had been in full swing for quite a while.
Last, while ancient life expectancy was low, for a myriad of reasons, studies of prehistoric bodies generally reveal much better muscle and bone structure than most of us have today. There is growing evidence that "natural" blood tends toward alkalinity, while modern humans' blood seems to be trending ever more acidic.
