Because animals had yet to be domesticated, Stone Age hunters could only eat wild animals whose body fat naturally waxes and wanes with the seasons.
....in wild animals such as caribou. Note that for 7 months out of the year total body fat averages less than 5.0 %. Only in the fall and early winter are significant body fat stores.
There is absolutely no doubt that hunter-gatherers favored the fattiest part of the animals they hunted and killed. Not surprisingly, these organs are all relatively high in fat, but more importantly analyses from our laboratories showed the types of fats in tongue, brain, and marrow are healthful, unlike the high concentrations of saturated fats found in fatty domestic meats.