I was curious recently about use of bones as food in the paleolithic. One interesting paper I found was Gazelle bone fat processing in the Levantine Epipalaeolithic. Epipalaeolithic is a term for an era confined to a particular geographical space of the Levant in the Eastern Mediterrean about the same time as the mesolithic era in Western Europe (21-11.5 thousand years ago). Hunter-gatherers in this era had more advanced tools than in previous eras. One thing they apparently used these tools for was to extract greater nutrition from animal bones. The major important products from bones were marrow and grease. Humans might not have the jaws of hyenas, who also consume bones, but we have the smarts to devise tools to get these nutritionally valuable products. The amount of time spent processing bones speaks to their nutritonal importance and also leaves good evidence.
While bone marrow is hard to extract, it was worth it for these hunter-gatherers considering how nutritious it was. There is evidence for marrow processing as early as 5 million years ago. Grease is also present in bones within the spongy microstructure, but it requires more technology to extract than marrow. The epipalaeolithic represented a bridge between foraging and sedentism, so at this point food was being stored. Grease could be stored in solid cakes, skin bags, or mixed with meat as pemmican. Extracting grease required pounding or breaking the bones and boiling them. The grease can then be skimmed from the surface. Back then most containers used were made of organic matter, which means there isn't a lot of good evidence for their exact nature. I remember some time ago seeing an argument on a paleo message board about containers, but this paper references evidence of organic containers that were probably heated with hot rocks from a fire, a method still used in some saunas I have attended.
How much and what kind of grease and marrow varied by animal species, age, season, weight, and physical condition. The species found in the Levant sites studied included fallow deer, tortoises, hare, and partridge.
This paper interested me because I've been thinking a lot about cooking methods and adopting those that are gentler than frying. The evidence is quite clear that boiling has been in use for a long time and also represents an excellent way to extract further nutrition from animals. The point that bones need to be broken to get the most of them is something to remember. Ask your butcher to cut your bones open so you can enjoy the marrow and make more nutritious and delicious stock. A cookbook that has some great info about what cuts to ask for is Bones by Jennifer McLagen.