Zooarchaeology and Taphonomy

Zooarchaeology as a discipline pretends to establish the relationships which exist between human groups and animals, establishing the character and the meaning of the skeletal pieces which appear in sites.

Hominids, like other predators, accumulate remains of their prey in temporal refuges or in referential places (campsites or dens). The study of these accumulations, their formation, nature and composition, constitutes a fundamental base in order to understand and comprehend human behavior in the past. Nevertheless, many problems with difficult solution persist due to the difficulty of the formation and conservation processes of the samples, which to a methodological level, their interpretation is studied by the science of Taphonomy.  The search of alternatives has taken us to establish links with different disciplines like Taphonomy Paleontology, Paleoecology, Etnoarchaeology, Zoology and Ethology, within others.

From a zooarchaeological point of view, it is possible to deduce, parting from the faunal record, the subsistence strategies of the human groups which lived in Bolomor Cave. In order to carry out an approximation, it is necessary to focus the attention in various elements:

1) Anatomical representation of the identified taxa

2) The age of death of these animal

3) The type and localization of the processing marks in the body, both if they have an anthropic origin, (cut marks and  diagnostic elements of anthropic fracturing) or produced by carnivores (bites and fractures).

4) Overlapped marks

The principal remarkable characteristic of the faunal assemblage of Bolomor is the anatomical representation which is biased by the animals depending on their weight. Only the animals with small weights (less than 20kg) show a generalized integrity of their skeletal elements. On the contrary, the animals with superior weights are represented fundamentally by the appendicular skeleton and by the cranial skeleton (skull and mandible). However, the elements that compose the axial skeleton (vertebrae and ribs) are practically absent. This phenomenon responds to a differential movement of the skeletons by hominids and is known by the name “Schleep effect”. As it has been evidenced, hominids of Bolomor Cave move the elements with a higher nutritional value to the site and abandon the less rich and more difficult to carry (rib cage) in the Kill site.

Series experimentales de procesamiento. Inicio de despellejamiento en el cráneo con herramienta de sílex.

Experimental series related to faunal processing. Skinning with flint flake.

Besides this anatomical selection, there are more evidences which show the systematic relationship of these human groups with the fauna. These are: the cut marks on the bone surface, the fracturing of the bones in order to obtain the marrow, the human bites and cremation.

During the butchery processes, this leaves marks frequently of the use of lithic industry on the bone’s surface. These marks are known as cut marks. The study of their position, delineation, and direction of the traces, allow us to recognize the activities that took place: peeling, evisceration, quartering, fleshing and bone dismantling. Nevertheless, the flesh is not only extracted with the use of lithic industry. Teeth are also used for defleshing and for the consumption of marrow, fat or/and cartilage of small animals such as rabbits, birds or tortoise.

fauna_04

a) cut-marks on rabbit (Oryctolagus cuniculus) tibia from XVIIc; b) cut-marks on humerus of swan (Cygnus olor) from XII; c) cut-marks on femur of red deer (Cervus elaphus) from XVIIc; c) cut-marks on mandible of rabbit (Oryctolagus cuniculus) from sublevel XVIIc; e) cut-marks on tortoises (Testudo hermanni) del nivel IV; f) cut-marks on long bone belonging to large-sized animal from level IV.

The presence of evisceration marks in some bone remains, the predominance of oblique and longitudinal incisions in the long bone diaphysis (skeletal elements which compose extremities) and the systematic reiteration of anatomical parts with a high level of nutritional value show that the principal strategy of subsistence of the hominids of Bolomor cave is hunting. This practice includes from simple hunting to more complex techniques such as, for example, multiple predation identified in level XII of the stratigraphic sequence. Another of the elements which reinforce these practices is the main presence of adult individuals. Healthy and strong animals are adults and the ones mainly hunted. Immature or senile, which aren’t found in their whole faculties, are an easy prey for carnivores, a potential indicator of secondary access for human groups.

Another activity related with the anthropogenic processing of animals is the use of fire. Many of the bone remains recovered in the site present signs of having been treated thermally. This can be due to two different phenomena: culinary activities or/and cremation of the remains once abandoned, be it accidentally or intentionally. In the case of Bolomor, we have recovered double colorations over the same bone surface which suggests the differential preservation of the meat in the moment of its exposition to fire, and so, it allows us to suggest the principal existence of the roasting of meat before the bone being defleshed.

Series experimentales de combustión. Asado de carne. 

Experimental series related to burning damage

Cremación diferencial de algunos restos óseos del nivel IV (Blasco y Fernández Peris, in press)

Meat roasting. Differential burning on bone remains from level IV.

One of the most important characteristics of the faunal assemblages of Bolomor Cave is the grade of fragmentation of the bone remains. This fragmentation is due, mainly, to the intentional anthropic fracturing of the bones in order to obtain the marrow. The human groups which occupied the site break the bones when fresh with the technique of direct percussion, which consists in hitting the skeletal element with a hammerstone. An evidence of this activity is the great quantity of diagnosed elements which have been identified, as are percussion pits, percussion notches and impact flakes.

Series experimentales de fracturación por percusión directa.

Experimental series related to hammer-stone percussion.

fauna_08

a) impact notches on tortoise caparace fragments (top) and resulting fragments in the form of impact flakes (bottom) from level IV; b, c) notch on humerus of red deer from level IV.

After the exploitation of the internal nutrients, the bones can be used as a prime material to start up operative chains of production. In Bolomor Cave, only punctually, some resultant element of the anthropic fracture is used as soft hammerstone. In the case of the sublevel XVIIa, the same element used as a hammerstone is also configured intentionally.

Fémur de ciervo del subnivel XVIIa con señales de su utilización como percutor blando (izq.) y con modificaciones antrópicas intencionales en forma de muescas contínuas y superpuestas (der.) (Blasco, 2011).

Femur of red deer used as soft hammer (left) and anthropogenic damage in the form of overlapped and continuous small notches. Sublevel XVII a (right).

The faunal remains are abandoned all over the occupied space and configure an attractive focus for carnivores. This is how we have identified the occasional action of these animals, which alter the ensemble, introducing some punctual elements both by their transport, defecation or regurgitation, modifying its spatial distribution. Apart from carnivore mammals, it has also been observed the punctual action of raptors over part of the marginal assemblage of rabbits.

Marcas de dientes de carnívoros en forma de depresiones sobre restos óseos del subnivel XVIIc: a) depresiones sobre una diáfisis de hueso largo atribuido a la talla media; b) depresiones sobre un fragmento vertebral atribuido a talla media (Blasco, 2011).

Carnivore tooth-marks on bone remains from sublevel XVIIc: a) pits on long bone mid-shaft attributed to medium-sized animal; b) pits on a vertebra fragment belonging to a medium-sized animal.

Once the nutritive phase of the bones has finalized, there is a series of agents and processes, both of biological and mechanical nature which act over the ensemble before and after being buried. The study of these is within the discipline of Taphonomy and gives fundamental data to comprehend the history of the site and to reconstruct the existent conditions during its formation process.

The post-depositional alterations which are most abundant in Bolomor are related principally with the presence of water and light in the cavity. In this way, we have recovered, punctually, bone remains with alterations produced by the exposition to atmospheric agents as weathering, the action of roots in the form of ramified grooves and, in a more accused way, the presence of concretions and manganese.

Alteraciones óseas post-deposicionales: a) diáfisis de hueso largo atribuido a un animal de talla grande alterado por la acción de los agentes atmosféricos (weathering); b) erosión por acción de raíces en forma de surcos y vermiculaciones sobre un hueso largo de un animal de talla media; c) vermiculaciones subactuales sobre una mandíbula de ciervo común (Cervus elaphus); d) manganesos generalizados sobre un húmero de ciervo común (Cervus elaphus) (Blasco, 2011).

Post-depositional bone alterations: a) weathering on long bone mid-shaft of large-sized animal; b) root damage on long bone belonging to a medium-sized animal; subactual root damage on red deer mandible; d) manganese on a red deer humerus.

From these modifications, the cavity, as we know it today, would show floors of humid occupations with a changing climate from more dry to humid in very determined occasions.

In a general way, the fauna of Bolomor Cave is characterized by a high grade of anthropization. The skeletal representation, cutmarks, fracturing, the thermal treatment of bones and the presence of human bites indicate the development of complete sequences of exploitation of animals by the hominids which occupied the site, and allow us to determine the human groups as the principal responsible of the faunal accumulations in the site.

Top