Interpreting the archaeological record for early hominid diet
Beginning 2.6 million years ago at sites in East Africa , we begin to find evidence of stone cobbles that have been deliberately flaked into pieces, and then dropped in clusters on the ancient landscape, sometimes associated with broken animal bones. These concentrations are called archaeological sites, and they preserve the debris left behind from the activities of our ancestors.... their "garbage" (e.g. stone tools, food remains, etc). FLK-Zinj, the site discovered and excavated by Mary Leakey at Olduvai Gorge, is an example of an early archaeological site like this (although it is a bit younger... around 1.8 million years old). Glynn Isaac referred to these sites as "stone age visiting cards" because they mark the locations where early hominids LIVED, not just where they died.
He identified different types of sites:
- sites containing only artifacts
- sites with animal bones and artifacts
- single carcass + artifacts (simple butchery sites?)
- multiple carcass parts + artifacts (more complex site or camp?)
- sites with bones damaged by artifacts, but missing the artifacts themselves (Bouri, the site where Australopithecus garhi was found, is a 2.5 mya site with this type of evidence pattern)
The artifacts are simply flaked stones (flakes and cores) and hammerstones... called Oldowan technology (named after Olduvai Gorge). Most are made on rocks that occur locally in the area... within a mile of the sites where they have been flaked, but a few artifacts at the Zinj site, for example, have been imported from a longer distance (further than chimpanzees are known to carry things, for example). No one is absolutely sure what they were used for, but experiments by Nick Toth (article in readings) and others show that they could have been effective tools for a wide range of simple tasks, such as pounding, chopping and slicing. (You got the opportunity to play with stone flakes and cores yourself in class on Thursday. ) Were they, in fact, used? Did they help early hominids acquire foods? The edges of a few artifacts at several early sites have been microscopically dulled and "polished" through use on hard and soft plant material, and perhaps meat, but few artifacts from these early times have been examined for use wear.
Similarly, some of the animal bones found in association with early artifacts show evidence of having been processed with stone tools.... percussion marks show evidence of smashing bones open for marrow, and cutmarks left by stone flakes suggest that early tool makers sliced meat off of some of the bones at early sites. Some of you discovered in class on Thursday that cracking a large bone open for marrow is not necessarily an easy task!
Note that even more bones at many of these sites show evidence of having been chewed by carnivores too! The issue becomes... who got to the bones FIRST? Was it hominids or carnivores? How can we tell? Damage patterns can only tell us part of the story.
Blumenschine's studies of scavenging in East Africa today have revealed interesting patterns of animals feeding on skeletal parts that can help diagnose what happened at archaeological sites. The key issues are:
- if you can kill an animal yourself, you have access to the entire carcass
- if you get there late in a scavenging sequence, your choices are much more limited... often all the flesh has been eaten away already, leaving only marrow bones... or, very late in the sequence, sometimes the hindlimb or upper limb bones have already been consumed, leaving only the meat-poor lower limb bones for the poor scavenger.
- Are you willing to carry all or part of a carcass away from the kill site, to eat it with less competition from other carnivores? Maybe you should leave the bones with the least food, or the heavy bones behind? Which parts should you take with you?
Thus, one of the issues zooarchaeologists look at is which BODY PARTS occur at a site, and which parts have different types of DAMAGE PATTERNS on them. The Olduvai CD-ROM shows examples of some of the results of experiments done that reveal different patterns of toothmarks and stone tool damage that you can compare to the actual damage patterns preserved on bones at the site to interpret how hominids got access to animal remains at FLK-ZINJ
We will talk a bit about how archaeologists count bones at a site... sometimes just comparing the raw number of bones for each animal at a site misrepresents the number of carcasses (or carcass parts) that were originally at the site. This is why NISP and MNI are important concepts to think about when analyzing the bone patterns at Olduvai.
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Last updated: November 3, 1999
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