11. An Ecological Niche - The Evolution and Development of an Ecosystem

The exhaustive analysis of the data, the defence of its credibility and the interpretation of the rich archaeological and palaeontological remains are nevertheless a poor reflection of past events. This study has been largely concerned to describe the extensive and diverse evidence from the Pin Hole Cave, as well as the many variations in interpretation that are often related to specific and sometimes isolated studies in both Quaternary archaeology, palaeontology and environmental information. The archival data upon which this is based is also made available.

This study raises doubts concerning the concept of a MAZ (Mammal Assemblage Zone) fauna and its identification within Pin Hole Cave, where the evidence of a vertebrate biome simply does not seem to relate directly to the 'Mammoth Steppe' fauna. The original definition of the faunal zone by Guthrie (1982) is ideally suited for the Alaskan Quaternary habitat. The attempted application of the concept to other areas of the Holarctic vertebrate distribution have not worked so well. This has generated a series of studies that has basically separated out the inappropriate sections of the vertebrate fauna on the basis of chronological or environmental difference. This has been extended to the point where the original concept has become meaningless. The increasing adoption of the various proposals suggesting ecosystems with high numbers of arctic species with preferences for cold climatic regimes and species who prefer temperate environments recognises that there are differences which appear to be separated geographically. There are many observations concerning the behavioural activities of humans and animals that have been set in this ecological framework. It has been suggested that this locality within the English East Midlands was part of such a habitat and where this area was of seasonal importance.

Until this point of the study, the main objective has been to seek an explanation as to why there is so much activity during the Late Quaternary within this particular location. An important question is how this locality related to the surrounding habitat within the region of eastern England. Currently many varying ecosystems are described in relation to separate studies, geographical areas and localities.

Many aspects of both human and vertebrate behaviour are considered in relation to the analysis of remains. In virtually all cases, attention has been drawn to the fact that the style of survival is rarely isolated but indicates a relationship within an ecological framework. Such relationships with all aspects of the environment can often be formative in the development of an ecosystem.

The evidence from Pin Hole, characterised by its sheer quantity and diversity, serves as a window where ecological behaviour suggests the appearance, development and expansion of a new ecosystem in the Late Quaternary. The hypothesis described takes account of the relative frequency of species within the population but in addition it is inclusive of all known species. In effect, this underlines the frequency of Hyaena, European Wolf, Wild Horse and Bison as key elements of the population which are associated with Woolly Rhinoceros and very low frequency of Mammoth. Inclusion of Rodents is made very difficult owing to the nature of the evidence.

The developments can be seen as a dispersal of ungulates across the region and the establishment of a trophic niche associated with graminoid populations. This was initially of crucial importance to large carnivores. A process of faunal changeover, seemingly generated by change in the trophic web, appears to have caused change and expiration in the larger carnivores who were replaced by smaller predators in the form of human groups and middle range or sized carnivores. Analysis of the evidence from Pin Hole, while obviously important on a site basis and relevant within the immediate ecotone surrounding the Creswell Gorge, also indicates circumstances that have a regional basis and help form the elements that were important in a developing ecosystem.

11.1 An interglacial enigma

Suspended sediment and calcretes in the current roof of the cave have been dated to the last interglacial. The excavated infill has produced a single Hippopotamus molar from stratigraphic level 11, 10ft (3m) below the stalagmite floor datum. The status of this single find is unclear. The two types of evidence indicate that a fauna of interglacial type once existed within the cave and may survive in unexcavated deposits further into the rear of the cave. These are behind and to the north of the prominent mound within the 'inner chamber'. The data simply indicate that deposits of this age existed within this site and they may have included Hippopotamus. Further research is required to establish their status. There is a possibility that Hyaena from the basal deposits within the cave are remnants of an interglacial faunal population. Remains of this age are known from at least three adjacent cave sites and numerous fluvial locations to the east. Species known from such sites include Steppe Rhinoceros, Hippopotamus, Hyaena and Bovid.

11.2 Carnivore dispersion and the expiration of Hyaena, Woolly Rhinoceros and Mammoth

The cave was colonised by carnivores and the population was dominated by Hyaena. Their remains indicate that residence was primarily in the cave rear where there is evidence of breeding in the form of foetal and juvenile bones. Analysis of the molar size indicates that these are some of the largest Spotted Hyaena known. Food resources are almost exclusively composed of adult and juvenile Woolly Rhinoceros and Mammoth, whose fractured and gnawed body parts littered the cave rear. Less frequent remains include those of European Wolf and European Brown Bear, suggesting both episodic residence and hibernation. Wild Horse, Reindeer and Bison are present in small numbers. Smaller vertebrates include wading birds, ducks and geese, and fish, particularly grayling. The carnivore population is diverse and appears to be well established, which is evident from the mutualist behaviour of the three large carnivores.

The composition of the faunal population suggests a summer and autumn presence where young and juvenile animals of all species are present. The apparent longevity in presence of three large carnivore species, associated with Mammoth, two perissodactyla and three artiodactyls (all of which are grazers) indicate a thriving population within a productive grassland or steppe. This is an established population with a preference for temperate conditions and who rely on developing seasonally prolific grazing with access to water, salt and shelter within a habitat that provides some protection from carnivores and parasites. The environmental conditions within the cave are not well known but the presence of sediments (composed of fine sand and silt, consisting primarily of decomposing limestone) and the lack of sediments and clasts indicative of cold conditions suggest that conditions were temperate, damp and near water sources. There is no evidence of local cold arctic conditions. Large carnivores are known from this site and five adjacent caves. The evidence of prey in the form of Mammoth, Woolly Rhinoceros and Wild Horse is of interest. With the exception of Horse, all have low reproductive rates but are known to breed (including Wild Horse) within the region. All of the species are difficult prey and arguably Mammoth and Woolly Rhinoceros may have been immune from predation. Scavenging for carcasses must have formed a significant contribution to food resources. Under these circumstances, the habitat and annual life territory of all of these species must have been extensive to provide sufficient grazing. The general well-being of individual populations, especially the Hyaena, which included adults, juveniles and newborn, argues that the species practised mutualist behaviour for grazing and migrated regionally. Modern species of Proboscidean spend significant parts of their life in close proximity to water resources, rivers and lakes. There are adjacent sites (within a radius of 70km) that contained elements of this vertebrate fauna, sometimes with Hyaena. In general terms, similar sites are a considerable distance away. Their occurrence within Quaternary locations within the eastern UK confirms this. Migration during the Quaternary must therefore have been along the eastern area of the UK and very rarely in a westerly direction. The most plausible explanation is that this vertebrate fauna is migratory, derived from the east and south-east, and who gradually migrate over the spring and summer months into areas of Doggerland and the eastern part of the UK to reach a habitat at a slightly higher altitude, cooler, and with fewer parasites and predators. It is likely that an ecosystem of this type largely pre-dates the arrival of human groups at Creswell.

11.3 The emergence of grasslands - Neanderthal migrants and scavengers

Human groups utilising Middle Palaeolithic technology to fabricate quartzite pebbles to produce simple cutting edges appear in the lower levels of the cave. These are mainly concentrated in the passage and lower slope in the cave rear in the levels 10-12ft (3-2.6m) below the capping stalagmite. The distribution of artefacts, Hyaena-damaged bone associated with undamaged surface cut bone suggest that Neanderthal occupation is not contemporary with large carnivores and was possibly later in date.

Food procurement revolves around the use of Woolly Rhinoceros, Mammoth and Bison cranial and limb body parts of both adult and juvenile animals. Reindeer is present in these levels and may be associated with Neanderthal activity. Analysis of surviving body parts suggests that these groups were scavengers but may have opportunistically hunted juveniles. All Reindeer remains were examined or identified during this study and a single Reindeer antler with a burnt surface was recorded. This provides evidence of the use of fire within the cave, possibly for cooking. Remains of at least two fish species and geese suggest temperate conditions with abundant fresh water nearby.

The components of the vertebrate population suggest a spring and summer presence on the site and the prevalence of temperate conditions. Differentiation of vertebrate bone debris that results from carnivore predation and human predation is seriously inhibited in the small compact cave passage and rear, which has such a dense frequency of bone fragments. The remains of both prey and predator within the cave indicate change within the habitat resulting from increases in population, particularly of ungulate species. Episodic increase in the vertebrate population are, of necessity, related to changes in the trophic web which involve dietary change or access to primary food resources, itself the result of environmental change. This is particularly acute for the dispersion of ungulate populations and mutualist exploitation of graminoids. The arrival of Neanderthals using simply made cutting edges as an additional carnivore within the trophic system is significant. Both carnivores, Neanderthal and Hyaena, are exploiting Woolly Rhinoceros, the most frequent herbivore. Both species also scavenge and hunt Wild Horse and some Reindeer. This is a period that witnesses the slow decline of the large early glacial species, Mammoth, Woolly Rhinoceros and Cave Hyaena. European Wolf now seems the dominant predator but not on the developed scale of previous Hyaena populations.

The inference of extensive territorial areas remains but slow population growth is accompanied by the clear decline of the dominant carnivore and its prey species. Neanderthals exercise the same mode of exploitation of the trophic system, aided by simply fabricated tools with cutting edges, seemingly resourced very locally.

11.4 Development of an ecosystem

Dramatic changes take place in the nature of the evidence, which includes an increase in the frequency of Reindeer, Wild Horse and European Bison. This is associated with a second appearance of Neanderthals, whose appearance within the cave is associated with more frequent lithics of more diverse type. The frequency of Hyaena, Woolly Rhinoceros and Mammoth is seen to be gradually decreasing. Remains of the ungulate species within the cave include evidence of breeding and therefore summer and autumn occupation of the area. The presence of breeding populations of three large ungulates that are known to practise mutualist behaviour in dispersion, feeding, the avoidance of predators and parasites suggest that the population is making use of increasing large territories. This must have utilised large areas of eastern England. The ethology of these species is known to have the capability, via access and grazing, to create grassland ecosystems that also generate increases in frequency and diversity of their own species. The implications of such developments within a developing trophic structure are enormous. It is within this context that Neanderthal groups appear with tools that are now fabricated using both quartzite and flint. The new tool types are more finely made and include cutting edges, scrapers and points, which suggest a more diverse range of actions related to carcass processing.

Analysis of ungulate skeletal parts is intriguing. Bison remains include all body parts including axial skeletal remains. This indicates transport of whole carcass remains into the locality. Both Reindeer and Wild Horse remains have more axial body parts present. This indicates much greater, if not total, control at kill or scavenging sites. Their occurrence with more diverse tool kits suggests that killing is within more controlled circumstances, which would indicate that hunting may now be normal practice. Bison remains are largely adult, Wild Horse are usually adult associated with some young. For Reindeer, the increased presence of juveniles of both sexes is associated with multiple male and female cast antler, presumably collected between spring and autumn. Their association with other species also suggests developed mutualist behaviour. This may be an initial indication of a developing pastoralist-type management system, which helps to guarantee control and therefore development and daily access to the main food resources. The occurrence of a collection of multiple cast antlers within the cave suggest storage of a raw material. The lack of carnivores rules out all possibility that this is not deliberate. This is not a practice currently associated with Neanderthal activity.

The continued decline of Hyaena, Mammoth and Woolly Rhinoceros, combined with the second arrival of Neanderthals and the increase in populations of Reindeer, European Bison and Wild Horse, are perhaps the most significant change associated with the biome in the eastern UK during the Quaternary. Expiration of Woolly Rhinoceros, Mammoth and Hyaena during this time may well have been the result of dietary and trophic change within the ecosystem, which may have been aided by climatic change. Further research is needed to examine the possibility of changes in corridors and routes for this migratory species.

The relationship between Neanderthals and Hyaena is of interest. At face value, such a relationship would have been competitive and carries the risk that predation over-exploits the available trophic resources. The observed decline in both Mammoth and Woolly Rhinoceros can be seen as part of a long-term decline and not directly associated with the arrival of a second predator, Neanderthals. It is likely that the first appearance of Neanderthals represents occasional sporadic use of the site and where Hyaena frequency was in decline or absent. This may have been not only occasional and dedicated to exploitation of the large ungulate species but could also have been substantially separated in time. Regionally, there are few instances of Neanderthal sites but the few known sites, whatever the predatory relationship, do seem to have an association between Middle Palaeolithic lithics and the large species of Mammoth and Woolly Rhinoceros, with isolated examples of the smaller ungulates. The image is one of a declining ecosystem dedicated to the exploitation of these two species. I do not believe that this qualifies as a component of a 'Mammoth Steppe' fauna, particularly as the most frequent species is thought to prefer temperate environments and the other two species are known from many differing environments throughout the Holarctic area.

Concurrently with these changes, the diversification and increase in frequency of ungulates must indicate an expansion within the area and diversification in the dietary resources of their territory. There are numerous modern studies that demonstrate that populations of perissodactyla and artidactyla can produce grassland, populated by their preferred dietary species of graminoids. This long-term process is often brought about by repeated use for grazing, defecation and trampling. This development is likely to have affected the entire area associated with the corridor into eastern England and into the territory on the eastern side of the limestone ridges. This development is a key component of a new ecosystem created by herbivores and their predators, including human groups. Change within trophic systems undoubtably generated behavioural change. Change in tool frequency and type is a necessary response to the clear evidence of carcass collection, butchery practice and utilisation of cast Reindeer antler.

The concept of establishment of a large ecosystem centred on developing grasslands requires further study, particularly in areas of potential corridors and Doggerland. Evidence from Pin Hole for this development is derived from stratigraphic levels that are considered part of the MAZ (Mammal Assemblage Zone) concept (i.e. levels 5-6), which is not compatible with the development of grasslands and the evidence of its vertebrate population described within this report.

11.5 Confusion and change in the nature of human and vertebrate habitats

Pin Hole Cave has a hiatus in the middle of the sediment infill (5-6ft (1.5-1.8m) below datum). At the time of Armstrong's excavation, this was recorded as a 'slab layer'. This is in effect an unconformity in sedimentation where probably water entering the cave from the rear roof ruptures has flowed down the southern facing incline of the sediment mound within the rear chamber. This seem to have helped the movement of fossils rolling downslope to be incorporated within the horizontal fill in the front of the cave. This appears to be a gentle and gradual process that has not produced an accumulation adjacent to a prominent blockage of the cave under the entrance roof ruptures. Although specific to the site, the effect upon the cave stratigraphy has made interpretation of this zone of middle to upper transition difficult.

Within the vertebrate population, there is continuity in the frequency and preservation of Reindeer, Wild Horse and European Wolf. There also appears to be a gradual increase over time. There is a massive change and colonisation of vertebrates, which include smaller carnivores, insectivores, rodents, birds, amphibian and fish species. Within a relatively short timescale, the number of species and their frequency increases the population size by a factor of 6. Lithic assemblages change from typical Middle Palaeolithic tool types to artefacts predominantly on flint flakes, often invasively retouched to produce a series of scrapers and points. These initially are increasingly associated with a backed blade assemblage in flint and chert. Separation of what are likely to be separate assemblages are difficult based upon the recorded stratigraphy and distribution. New types of evidence appear that include engraving, bone and ivory work, a Jurassic fossil, amber and mother of pearl. The remains are predominantly in the front of the cave. In the background to this massive change, the occurrence of Reindeer, Wild Horse and European Wolf continue and perhaps increase. The evidence ceases abruptly in the top of the sequence to be followed by random evidence of Mesolithic artefacts and a few post-glacial vertebrates.

Despite the difficulties of interpretation, the evidence suggests a local and necessarily regional flourishing of the grassland ecosystem and its associated self-feeders and predators, including humans. It seems likely that human activity flourished elsewhere but the evidence within the cave indicates expansion and diversification.

The relatively rapid and sudden appearance of woodland and aquatic species must be the result of the huge environmental changes at the end of the glacial. For ungulates and their dependant predators, this is an era of disruption of migratory routes, changes in territoriality, and probable destruction of habitat in terms of required area and content i.e. the demise of the Quaternary ecosystem. Within Pin Hole Cave, the archaeological evidence of the Upper Palaeolithic largely occurs in the front of the cave. This area has received sediment and items of older age that have moved down the slope from the rear. The cave rear itself is, at this time, very difficult for humans to access. The cave is also becoming increasingly wet, leading to the formation of calcretes and stalagmite formations associated with the roof ruptures. Human occupation is characterised by a total change in lithic technology and lithic types, direct evidence of the use of Reindeer, almost exclusively as a food resource. Cast Reindeer antler is collected and preserved within the cave along with antler and crania that have evidence of butchery. The diversity of remains extends to bone and fossil ivory work, engraving, collection of marine shell and a Jurassic fossil. In Creswell Cave terms, there is a more intense use of the cave. In European terms the evidence of use is scant to say the least, with indications of a very low level of activity. This suggests that the focus of activity is elsewhere, probably in an open situation or that the cave has a specific function. The collection of cast but used antler, lithics that are mainly in pristine condition, fragments of engraved art and curios suggest that the cave may have been a 'cache' area and not a centre of occupation. Evidence of charcoal concentrations are reported by Armstrong and when seen by the author were stored in tobacco tins within the Manchester Museum. These are associated with a blade assemblage and may indicate occasional residence. Within the cave, large numbers of new species are known, including small carnivores, insectivores and bats, rodents and birds. Many of these species are resident and many are known not to tolerate human presence. This is a further indication that human presence may have been occasional within the cave.

In a regional context, this is a period of expansion - archaeological sites of this general age are known from vast areas of the eastern UK. Distribution is known from lithic finds and the preservation of palaeontological remains is rarer. Prey species are now almost exclusively Reindeer, with occasional evidence of Wild Horse and European Bison. It is very clear that human groups and at least Reindeer operate on a mutualist basis in terms of trophic resources. It follows that the huge rise in the frequency of archaeological evidence must have applied to the Reindeer population and their remains. The dilemma may be one of preservation. At least one location near to Creswell (Farndon) has lithic evidence of Upper Palaeolithic type associated with the south side of the River Trent, a feature that bisects any route. There are no palaeontological remains.

The environmental circumstances of Doggerland also alter at this time particularly from gradual sea-level rise and the potential submergence of grassland and disruption of hereditary migratory routes and corridors. The circumstance of local and regional (in UK terms) expiration of Reindeer and Horse are unknown but are unlikely to be the result of over-hunting and may be due to climatic change that altered the trophic web within the grassland ecosystem.

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