Zooarchaeology: What Animal Bones Tell Us About the Past
Zooarchaeology — the analysis of animal remains from archaeological sites — is one of the most informative subdisciplines in the field. Animal bones are among the most durable and abundant materials in most archaeological deposits, and the information they contain goes far beyond simple questions of what people ate. Age at death profiles document herding and pastoral strategies; cut-mark patterns and bone fragmentation record butchery practices and cooking methods; body part representation reveals trade and redistribution; stable isotope analysis indicates where individual animals were raised; ancient DNA from bones identifies domesticated species' origins and documents breeding history. Zooarchaeology addresses questions of economy, ecology, seasonality, ritual, and human-animal relationships that no other evidence type can answer with comparable precision.
What Survives and What Doesn't
The starting point is taphonomy — the study of what happens to biological material between death and the archaeologist's trowel. Bone survives differentially: dense cortical bone (the outer shell of long bones, teeth, and cranial fragments) lasts longer than trabecular bone (the spongy internal structure of vertebrae, ribs, and epiphyses). Acid soils dissolve bone rapidly; alkaline or waterlogged conditions preserve it. The assemblage a zooarchaeologist receives is therefore a filtered sample, and the filtering processes must be understood before the original population can be reconstructed.
Animal agents further modify assemblages: carnivores gnaw bones, creating characteristic tooth-mark patterns and concentrating bone at den sites; rodents gnaw bone for minerals, leaving distinctive incisor grooves; birds of prey swallow small vertebrates and regurgitate pellets of bone at roost sites. Human butchery leaves cut marks from stone, bone, or metal tools that are distinguishable from carnivore tooth marks under the microscope. Distinguishing all of these agents from each other, and from post-depositional processes, is the first task of zooarchaeological analysis.
Age and Sex Determination
Determining the age at death of individual animals — from tooth eruption sequences, tooth wear, and bone fusion stages — reveals the management strategy behind the assemblage. A herd of sheep managed primarily for wool will show predominantly adults; a dairy-managed cattle herd will show a high proportion of young males slaughtered as calves. A hunting assemblage dominated by prime adult males reflects selective hunting of trophies or meat; a predator kill site shows more old and young animals (the most vulnerable). Age-at-death profiles are among the most direct lines of evidence for domestication and pastoral practice.
Sex determination from bone morphology or ancient DNA reveals the sex ratio in the assemblage. A concentration of female cattle with calves but few adult males suggests a dairy herd managed for milk production. A surplus of male cattle skulls in an urban Roman deposit indicates the centralised slaughter of male livestock bred in the countryside and transported to the city.
Butchery and Cuisine
The pattern of cut marks on bone surfaces documents butchery practice: where the meat was removed, whether the carcass was processed in the field or at the settlement, and how the bones were subsequently processed for marrow or grease. Experiments with different tool types on animal carcasses have established the characteristic mark morphologies produced by stone flakes, bronze knives, and iron cleavers, allowing the identification of tool type from marks alone in many cases.
Burning patterns document cooking: bones roasted in the fire show characteristic spiral fracture patterns and colour gradients; bones processed for bone grease are smashed to extract marrow and may be boiled in pots (leaving pot-polishing marks and chemical signatures in the bone surface). The zooarchaeological evidence for cooking methods at many sites is more detailed and reliable than the artefactual evidence.
Domestication and Livestock Origins
Ancient DNA from archaeological bone has transformed understanding of where, when, and how many times domestic animals were domesticated. Cattle (Bos taurus) were domesticated from wild aurochs (Bos primigenius) at least twice, once in the Near East around 10,000 years ago and independently in South Asia; a possible third domestication event in Africa is debated. Sheep (Ovis aries) were domesticated once in the Near East; goats (Capra hircus) similarly once. Horses were domesticated in the Eurasian steppe around 3500 BCE; pigs (Sus domesticus) were domesticated independently in at least two regions (Near East and East Asia). The morphological changes associated with domestication — reduced body size, changed horn form, changes in skeletal robusticity — are visible in the bone record and allow the transition from wild to domestic to be tracked in the zooarchaeological sequence at specific sites.
Fish and Marine Mammals
Fish bones are a major source of dietary information at coastal and riverine sites, but their small size means they are easily missed in hand collection. Fine-mesh sieving (0.5–2 mm mesh sizes) of archaeological deposits recovers fish bone, small mammal bone, and other microfauna that coarser excavation methods miss entirely. The introduction of systematic sieving in the 1970s and 1980s transformed understanding of the role of fishing and marine resource exploitation in prehistoric diet: many sites that appeared, from hand-collected bone, to have subsisted primarily on large game were revealed by sieved samples to have had a substantial fish and shellfish component.
Stable isotope analysis of human skeletal collagen (carbon and nitrogen isotope ratios) corroborates the dietary evidence from zooarchaeology at the individual level: the ratios of C13/C12 and N15/N14 in bone collagen reflect the long-term diet of the individual across their lifetime. High marine protein diets produce distinctive isotope signatures; individuals with marine isotope signatures found in inland graves document the transport of dried or salted fish over considerable distances.
Ritual and Symbolic Use
Not all animal deposits in archaeological sites represent food refuse. Deliberately placed animal burials — dogs interred in the same manner as humans, horse burials associated with high-status individuals, cattle skulls embedded in Neolithic house walls at Catalhoyuk — document the ritual and symbolic dimensions of human-animal relationships. At Avebury in Wiltshire, zooarchaeological analysis of the deposits associated with the construction of the stone avenue found that pig mandibles had been deposited in a specific and non-random pattern suggesting deliberate selection and placement. The Hallstatt Iron Age deposits at the salt mine workings contain cattle sacrifices that document the ritual opening and closing of mining seasons.