10. Concepts of an Ecological Niche

The concept of an ecological niche is inclusive and multi-dimensional. It includes not only the habitat where a species may live, its trophic niche, where it eats, but also its relationship and role in the environment.. Odum and Barrett expressed the concept succinctly when they stated that habitat is a species' 'address' but a niche is its 'profession' (Odum and Barrett 1971). In modern ecological studies, a niche may have infinite terms of reference but many of these are not available for study in a Quaternary example. It is, however, possible to consider the evidence for a common set of terms relating to occurrence, behaviour and relationships with and within the area and which seem to differ from the surrounding circumstances. The concept of an ecological niche and its existence within the Quaternary landscape of the East Midlands of the UK and Doggerland is a central issue of this study. Recognition of such a concept relies heavily upon the recognition in both the archaeological and palaeontological evidence of a discrete region characterised by its topography, heterotrophic resources, autotrophic processes and apparent concentrations of evidence and where edges can be defined (Odum and Barrett 1971).

10.1 North Sea Basin and Benelux countries

Comprehensive discussion of the now-flooded North Sea Basin and its terrestrial bridges with the Benelux countries and Eastern England are complicated by the fact that much of the area is of limited availability for research. Projects related to the development of the oil and natural gas extraction have considerably increased awareness of sub-surface geology. Developments within the fishing industry and the dredging of water channels in the Benelux countries have produced large collections of palaeontological and archaeological material of Quaternary age. It is not the intention of this study to consider these discoveries in detail but there are two observations that are important.

Firstly, the Quaternary landscape in the area to the east of the English mainland was composed of a basin, particularly in the southern area, of lower lying land bisected by fluvial systems draining from the higher area of the Fenno-Scandinavian graben and towards the south-west. Although the details of topography are poorly understood, the southern and eastern areas seem to have been bordered by higher ground. Although sea levels and available dry land are known to vary considerably during the Quaternary, in general terms the area offered a large basin with multiple watercourses and which was bordered by what is now the coast of eastern England. Much of the landscape of the Eastern UK is characterised by large river valleys that drain east and south-east into the general area of the lower lying basin. The area presents a considerable topographic barrier (in terms of routes) in the form of higher ground to the north, associated with the Fenno-Scandinavian graben. Secondly, despite the absence of temporal detail relating to archaeological and palaeontological finds from the North Sea Basin, it is clear that they occur in considerable scale and diversity. Multiple sites are known to be of Middle to Late Quaternary age. Discoveries are more frequent in the southern area of the basin, characterised by its one-time land bridges to England, and demonstrate that a habitat has existed for both human groups and animal populations within the Quaternary that was continuous with the mainland UK until sea level rises in the Late Quaternary. Studies of both archaeological and palaeontological remains suggest a commonality in material across the area during the Later Quaternary. The frequency of remains appear to diminish to the north and, south which may suggest the presence of an edge of a habitat and niche.

10.2 Eastern UK, routes, corridors and seasonality

The area of Eastern England offers a route and corridor to the north-west of the European plains. The corridor is concentrated between the lower lying basin and the waterless higher ground of central England. The region occupies a terminus that was episodically available during the Quaternary along a corridor accessing the lower North Sea basin and which runs in a north-westerly direction along the higher ground adjacent to the present coast of Eastern England. The route disperses or is unavailable in the regions of higher ground to the north-west. Existence of the corridor is supported by the apparent concentration of evidence from the North Sea within this area and the dramatic decrease in evidence within regions to the west and central England. Quaternary sites, particularly those of palaeontological interest, are distributed throughout the region, often associated with river valleys. To the west and relatively higher waterless areas, appropriate sites are far less frequent. The nature of site distribution suggests a biome where little intra-species competition is present and topographic variation was a significant control.

It is clear that the dividing area between east and western UK is an environment that would have provided difficulties for both human and animal dispersion and colonisation. The area is generally composed of slightly higher altitude limestone ridges whose impervious nature severely limits the amount of surface water and which must have acted as a constraint and barrier to habitation. Additionally and in significant contrast to the eastern area, the exposed geology has little available salt reserve, which would be of considerable importance to animal populations generally and ungulate populations in particular. Adequate accessible salt reserves are otherwise confined to some areas in the east and to maritime areas. Their occurrence does seem to overlap with the known distribution of both human and animal populations.

The context of Eastern UK sites has featured in several studies. Stuart (1982) in his study of British Quaternary vertebrates has pointed out that there is a more dense distribution within the east. Of particular note are his comments that virtually all the evidence for fossil Hippopotamus (Hippopotamus amphibius) is derived from this area and is absent from the west. Studies of the distribution of archaeological evidence by John Campell (1969; 1977) have also drawn attention to a boundary between east and west, particularly in central England, which he has argued may be a territorial boundary. Campbell's distinction was largely based upon geographical distribution and the lack of sites within Central England, but he also pointed out differences in lithic technologies and suggested that these may have a cultural foundation.

10.3 Movement and aggregation

Motivation for movement is likely to have been a combination of vigality of the species itself, pressure generated by population increase, and the necessity of predation and parasitic avoidance causing movement to areas with fresh feeding and breeding opportunities (Allee et al. 1949). For ungulate populations regional movement is likely to have been of large scale in terms of area, population numbers and diversity. The available vertebrate faunas consistently indicate spring and summer movement of large ungulates. In some cases, this is accompanied by evidence of diverse avian populations, many of which were migrating into the region from more temperate wintering areas. This is also multiple, clear evidence of aggregation of human groups and vertebrate populations within lacustrine habitats and river valleys in the eastern region of England and the coastal areas of Holland. In terms of species diversity and frequency, this appears to be of considerable significance.

10.4 Habitat - ethology-paleo-ecology of the Magnesian Scarps of the East Midlands

The region is largely one of undulating open landscape divided by multiple rivers, draining to the east and south-east. Within the northern parts of the region the narrow outcrop of Magnesian Limestone has produced a distinctive feature where the scarp is cut by multiple small rivers and valleys. In some areas, this is associated with areas of open water. Despite the climatic variations known during the Quaternary, the region must have been characterised by local sheltered features which softened the concept of an otherwise open steppe landscape.

Several authors have noted regional concentrations of elements that describe a niche of this type, and a few are known from Quaternary studies particularly from regions with concentrations of vertebrate populations (Stuart 1982; Brown et al. 2013) within the UK and Europe. There is little doubt that both archaeological and palaeontological evidence from the East Midlands of England, and particularly that concentrated around Creswell Crags, is exceptional within the context of Late Quaternary evidence from the UK. The prolific survival at Creswell appears to reflect a reality that is difficult to explain away as an accident of discovery or preservation within caves. This suggests that the location and its region offered resources during the Quaternary that served as an attraction to moving human and animal populations. Such resources appear to offer greater opportunity to these groups than those generally offered by adjacent regions.

Palaeontological evidence of species, despite temporal change, is also different in type and frequency from adjacent areas. Human occupation indicated by lithics is more problematic. The typology of Middle Palaeolithic lithics has been compared with those of the Mousterian of Acheulean Tradition of south-western France. Similar typologies from the Later Middle Palaeolithic (Early Upper Palaeolithic in the UK) and the Later Upper Palaeolithic backed blade industries have their closest affinities in the European Plain and are of a different nature in adjacent areas.

The significant concentration of Quaternary evidence examined in this study offers no clear and comprehensive indication of the causal factors that would go some way to explain the circumstances associated with a dispersion of species into a fairly remote peninsula of north-western Europe. The nature of the archaeological and palaeontological evidence suggest an episodic occurrence of low frequency, which does not seem to justify a concept of colonisation by a developing and expanding vertebrate and human population but is more likely to indicate the arrival of populations that have been displaced from a more centralised focus in Eastern and Central Europe. Causal factors of such displacement are unclear but are likely to be multiple and include population growth and the inherent pressures for territory, climatic change and a shift in the location of appropriate breeding areas and perhaps technological change by human groups. One factor that is clearly suggested by this site is that for vertebrate populations, the Quaternary is a period of long-term decline rather than expansion and that its closing stages sees the arrival of a different, more diverse and numerically more frequent vertebrate population that does appear to have expanded and colonised the UK during the Early Holocene.

10.5 Holarctic vertebrate populations, long-term indication of east-west movement

A significant study by Guthrie (1982) of Alaskan vertebrate faunas has drawn attention to a Mammoth Steppe fauna that has moved within the Holarctic region of the Northern hemisphere. Subsequent studies by Semenov (2014) and Řičánková et al. (2015) have argued that variation in habitat on a regional basis is more varied than the original concept of a cold steppe environment. Řičánková et al. have suggested that coeval vertebrate populations contained both 'cold' and 'temperate' elements, which are documented for a long history of vertebrate expansion and contraction within the biome. This has culminated in the regional expiration (extinction) of some species in the central European steppes. The formal Mammoth Steppe fauna is widely regarded as tolerant of cold conditions and characterised by population increase in both frequency and diversity and capable of expansion (Semenov 2014). Ideas concerning the ethology of the Mammoth Steppe fauna strongly support the view that the eastern region of England, and in particular the region of Creswell Crags, has experienced episodic expansions of this fauna from its focus in eastern and central Europe. The lack of evidence is not evidence but alternative Holarctic or temperate faunas from other southern European locations are unknown.

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