A year or so ago I did a powerpoint presentation for a nutrition lab on how past diets are generally reconstructed. I am by no means an expert on the topic (I focused much more on evolutionary genetics and biochemistry in my coursework than bio-archaeology) but here's a brief overview:
Primatology -
Archaeology -
Bones -
Primatology -
- Insectivores – frugivores – folivores – exudates – omnivores – seasonality of food – group dynamics
- 96% shared base pair sequences between humans/chimps
- Human brain 3x larger than chimpanzees – consumes about 25% of our calories -
- Terrestrial – bipedal – energy expenditure
- Kleiber's Law – Expensive Tissue Hypothesis
- Hindgut/Foregut Fermentation – larger colons, smaller intestines
- comparative anatomy
Archaeology -
- Weapon usage – different for different species – points toward hunting habits
- Cooking tools – conjectured usage from structure – granules of food particles left -
- Coprolites – fossilized feces – place in trisodium phosphate for 72 hrs – turns dark brown/black if it's human – point to extreme dietary diversity, high fiber diets – H. Erectus oldest found: shows charcoal, mollusk shell fragments, and sand grains.
- Paleontologists rectify climate, ecology and chemical techniques to reconstruct the potential diet of the individual species
- C3/C4 Plants – Plant evolution, rubisco, efficient in drier climates – C3 wild plants in temperate regions, C4 domesticated grains, sugar – carbon isotopes 12/13 reflected in bone collagen/apatites – bones show average, enamel shows at time of formation
- Nitrogen 15 – amount in bones reflects animal protein in diet – can skew past diets if individuals found were in differing societal hierarchies
- Sr:Ca ratio – high Sr = veg, low Sr =carn
- Otzi's Hair - last meal showed deer meat consumption and potentially cereal grains (fun fact: he had tattoos)
Bones -
- Electron microscope images of mammalian long bones – cuts made by stone tools incised above carnivorous teeth marks – evidence for scavaging - believed that food parts like scavenged marrow constituted large part of initial animal food consumption
- Markings/Scrapings/Burnings
- Diseases – Osteoarthritis, Osteoperosis, cribra orbitalia and porotic hyperostosis
- Harris Lines – growth stunts, mineralization continues
- Humans have two incisors, one canine, two premolars, 3 molars
- Generalized use – good for shearing, grinding, shewing – ability to chew leaves , seeds, meats, etc
- Less dimorphism
- Humans have thick enamel – tricky – thin enamel wears to make gradient for shearing with dentin
- Past dental wear/caries -food trapped within
- high crowns and high cusp relief with shearing crests are thereby well-suited for eating tough foods like leaves and stems
- Pet Peeve Alert: Though I don't believe vegetarianism is the 'ideal' human diet, pointing at canines and asking why we have them just makes you look dumb. Lots of largely vegetarian animals have canines - horses, hippos. Chimpanzees are have huge canines but are largely non-meat eaters besides the occasional colobus monkey. Canines are largely dimorphic and have more of a role in sexual competition.
- Light-microscope wear patterns
- Macrobotanical remains – large fragments of preserved vegetal material
- Microbotanical remains – phytol
- Phytoliths – silica bodies that form in the cellular system of plants that remain in dental caries, cooking pots – last meal effect, indicative of last meal eaten, not necessarily normal diet
- Pollen grains
- Protein, fatty acid, DNA residues
- Plant impression on fired clay, pot sherds, floor, etc
- Pyrolysis gas-chromatography-mass spectrometry of plant microfossils
- Electron Spin Resonance – tests highest temperature a material have been cooked at and duration of heating
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