Review of ‘The Willandra Lakes Hominids’ by S.G. Webb and ‘Coobool Creek. A Morphological and Metrical Analysis of the Crania, Mandibles and Dentition of a Prehistoric Australian Human Population’ by Peter Brown
21st May 2014
‘The Willandra Lakes Hominids; by S.G. Webb, 1989, Occasional Papers in Prehistory, No 16. Department of Prehistory, Research School of Pacific Studies, The Australian National University, Canberra, ix + 194 pp. ISBN 0-7315-0802-5 (pbk).
‘Coobool Creek. A Morphological and Metrical Analysis of the Crania, Mandibles and Dentition of a Prehistoric Australian Human Population’ by Peter Brown, 1989, Terra Australis 13. Department of Prehistory, Research School of Pacific Studies, The Australian National University, Canberra, xxi + 205 pp. ISBN O-7315-0742-8 (pbk)
Review by Phillip J. Habgood
These volumes have been reviewed elsewhere (e.g. Pardoe 1991;Wood 199l), but their importance warrants a further review and discussion in this journal. The two monographs provide detailed discussions of two of the best collections of skeletal material recovered in Australia and add to the ‘academic’ debate on the origin of the Australian Aborigines.
The Willandra Lakes Hominids by Steve Webb is a detailed catalogue and general description of much of the skeletal material recovered since 1974 from the Willandra Lakes in western NSW (94 individuals). Although Lake Mungo 1-3 (WLH1-3)and WLH50 are not part of the survey, their combined shadow looms over the entire work with LM 1 adorning the cover.
The monograph is divided into two sections. Section 1 is divided into a number of chapters detailing the anatomical and pathological characteristics of the sample and its place in the palaeodemography and palaeoanthropology of Australia Section 2 is a detailed catalogue of most of the individuals within the sample, including morphological and metrical descriptions and excellent photographs.
In the Preface, Webb states that he hopes the monograph ‘will lead to a greater appreciation of the scientific importance and world heritage value of a region where serious archaeological work has effectively ceased’. He has easily achieved this aim.
Chapter 1 outlines the history and curation of the collection and includes a very useful table detailing the catalogue number, site location, whether cranial and/or postcranial material is preserved, if the bone has been cremated or burnt and the proposed sex of each individual in the series. The chapter also includes a discussion of the dating of the collection. Webb interprets the available evidence as indicating that ‘with few exceptions, all individuals in the collection predate the end of lunette formation at the Willandra Lakes around 15,000 B P (p.7). The condition and taphonomy of the human bone is discussed in Chapter 2. This chapter explains the fragmentary nature of the human skeletal material. The section outlining the impact of cultural factors is especially interesting. Webb identifies ten individuals in the series which exhibit the same range of colour and bone condition as LM 1,which had been cremated and then smashed. Some individuals, including LM 1, appear to have been smashed prior to cremation as well as following cremation. Webb also suggests that the fragmentary condition of some of the individuals in the series may have been caused by deliberate bone smashing before internment.
As outlined in Chapter 2, the skeletal material that makes up the Willandra Lakes series is very fragmentary, especially when LM 1 and 3 and WLH 50 are excluded. Chapters 3 and 4 detail the morphological and metrical information that can be obtained from the material. To overcome the limitations of the cranial sample, Webb developed methods of assessment that he applied to certain sections of the cranium that were most frequently preserved- particularly cranial thickness, supraorbital development and size and shape of the malar. Pathologies such as osteoarthritis, Harris lines and dental hypoplasia and cranial and postcranial trauma evident within the sample are outlined in Chapter 5.
Although not actually part of the series dealt with in the monograph, the discussion of the cranial shape and thickness of WLH 50 will especially interest many palaeoanthropologists and biological anthropologists. In summary, Webb argues (p.70) that the extensive cranial thickening of WLH M is pathological and probably derived from some form of haemoglobinopathy (see also Habgood 1989a; Webb 1990). However, even if this diagnosis is correct, WLH 50 remains a very large and robust cranium.
In Chapter 6, Webb attempts to place the Willandra Lakes collection into the wider Australian palaeoanthropological context. This discussion is directed by the conclusions reached in Chapters 3 and4, where Webb determined that the analyses showed a consistency of separation between robust individuals and a gracile group and revealed a vast difference in male morphology within the series. Webb states ‘The likelihood of WLH 1 and 50 ‘sister’ and ‘brother’, WLH 3 and 19 ‘brothers’ or WLH 1 and 45 ‘sisters’ is unacceptable’ (p.76). Webb does not think that sexual dimorphism can explain all of the morphological differences. Pardoe (1991), however, has suggested that the separation is a result of sexual dimorphism (robust=male and gracile=female – with some overlap such as WLH 3) and that the distribution is typical of population variation. Although Webb is of the view that better-preserved and dated material is required before questions concerning the morphological structure of the first Australians can be answered, he goes on to support separate migrations – an early migration of robust individuals and a subsequent migration of gracile individuals. However, unlike Thorne (e.g. 1976), Webb contends that the migrations were from the same geographical area, Sunda, and the morphological differences reflect evolutionary trends within that region, not separate ‘homelands’. He is of the view that intermixing of the two forms/groups with the larger phenotype dominating overall, accounts for the large range of morphological variation evident in the terminal Pleistocene populations throughout Australia.
I do not intend to discuss the evidence against Webb’s conclusion, however, it should be noted that arguments against Thorne’s dual source and regional continuity hypotheses can also be raised against Webb’ s suggestion (e.g. Brown 1981, 1987; Habgood 1985, 1986b, 1989%1989b, 1992).
Coobool Creek A Morphological and Metrical Analysis of the Crania, Mandibles and Dentition of a Prehistoric Australian Human Population is a revision of Peter Brown’s PhD thesis. The monograph is divided into seven chapters and an appendix. The Coobool Creek sample is part of the Murray Black Collection of Aboriginal skeletal material ‘collected’ from the Murray Valley by the late George Murray Black As Brown details, the precise geographic location of the Coobool Creek cemetery is unknown and contamination has prevented radiocarbon dating of any of the material. Brown indicates in the introduction (Chapter 1) that the objective of the monograph is the morphological and metrical description of the crania, mandibles and dentition from Coobool Creek and its comparison with other material from Australia. Like Webb, Brown easily achieves his aim.
Chapter 2 outlines the material, including comparative samples, and methods, both metrical and statistical, used for the study. Brown also provides a detailed discussion of the method used for sex determination of the Coobool Creek sample and the comparative material. The results of morphological and metrical, both univariate and multivariate, analyses of the Coobool Creek crania are detailed in Chapter 3. This chapter also includes sections on sexual dimorphism and artificial cranial deformation (see also Brown 1981). Similar morphological and metrical studies of the Coobool Creek mandibles and dentition are contained in Chapters 4 and 5.
Chapter 6 outlines the conclusions that Brown reaches from the preceding analyses. The major finding is that the analyses align the Coobool Creek individuals with those from Kow Swamp, but differentiate them from recent and mid-Holocene skeletal samples from the Murray Valley. Overall size and the effects of artificial cranial deformation are the major distinguishing features. The association with the Kow Swamp sample (morphology and cultural practice of artificial cranial deformation) is used to persuasively argue for a late Pleistocene age for the Coobool Creek collection. Brown points out that the metrical comparisons of the Coobool Creek-Kow Swamp sample with Holocene collections indicate major reduction in the oro-facial skeleton, cranial vault and dentition. A similar pattern of size reduction is evident in other parts of the world. Brown discusses the various explanations that have been proposed to account for this phenomenon, and proposes that environmental changes such as a reduction in mean annual temperature may be the cause. The evaluation of this hypothesis must await more information and analysis.
Migrations – a new beginning
Webb stated that ‘The wide separation of the two identified groups makes it unlikely that they occupy the two extremes of a continuous range of variation, as a number of people have claimed’ (p.34). I am one of those people who argues against two morphological and chronologically separated groups migrating to Australia (Sahul) and who claims that the material documents a large range of morphological variation.
What mechanisms could be involved in the development of the morphological variation that is evident in the corpus of late Pleistocene skeletal material from Australia? Brown does not discuss these matters in any detail in his monograph (but see Brown 1987), but Webb discusses how genetics and migration can impact on skeletal morphology. He is not of the view that this can account for the full range of morphological variation evident in the Australian Pleistocene sample. Elsewhere I have argued for a population/genetic approach to explaining the large range of morphological variation (Habgood 1986a, 1987, 1991).
The limited archaeological remains recovered from late Pleistocene sites indicates a very dispersed low intensity population (see discussion in Habgood 1991). As groups colonised the continent (Sahul-Greater Australia) they moved into a diversity of terrains and climates. It is probable that these colonising groups would have become isolated from each other due to the enormous size of the continent and the relatively small population numbers. There are few significant topographical barriers in Australia, except the expanses of ocean that now separate Tasmania and New Guinea from the mainland, and so total isolation of the groups would have been unlikely.
If small groups were isolated, one could expect to find unique local artefactual specialisations, which would be adaptations to local conditions. The tula adze found in the arid regions of northern Australia, ground stone hatchets from sites in Arnhem Land, northern Australia, and small tools recovered from early sites in southwestern Western Australia may be examples of this form of local adaptation Geographical isolation would have been accentuated by the last glacial maximum, centred around 18,000 BP, when one can expect populations to have decreased (see Habgood 1991 for references). Small population numbers spread over large geographical distances would have been the major isolating mechanism in late Pleistocene Australia. Geographical isolation is a reversible phenomenon which in itself does not affect the separate groups (gene pools), but allows other processes, such as founder effect, selection, mutation and genetic drift, to accumulate genetic differences.
It is improbable that the small isolated groups would be a representative cross-section, morphologically or genetically, of the parent population. This would also have been the case for the initial migrants to Sahul. If the groups consisted of members of the same family lineage founder effect would have been accentuated.
Habitation of different environments would allow different kinds of selection to act on the individual populations causing genetical frequency variations to develop since human biological variation is determined by the interaction between the environment and genetic systems. Within small populations random genetic changes or mutations stand a greater chance of becoming fixed, allowing random genetic differentiation of the groups.
Under this model, small isolated groups scattered throughout the continent during the late Pleistocene would have been developing genetic variation. Genetic variation does not necessarily equate with morphological variation, but as the modern Australian Aborigines demonstrate, there is a certain degree of correlation (Kirk 1981).
Each of the isolated groups could have developed unique genetic combinations and so while they were internally homogeneous, they differed from other groups, thus producing a heterogeneous continental population. If there are chronologically separated groups within the Willandra Lakes sample, this phenomenon, along with sexual dimorphism, may account for the differences in morphology identified by Webb (i.e. chronologically separated unique morphologies [gracile type, robust type, and types in between] that developed locally). Gene flow would have been restraining the genetic differentiation, but its effect would have been limited by the isolation of the groups. It is significant that sites such as Kow Swamp and Coobool Creek, located in the Murray Valley where isolation would have been reduced and gene flow high, have skeletal samples that display a large range of morphological variation (accentuated by artificial cranial deformation).This may also be the case at the Willandra Lakes if the sample does not span a long chronological period or represent separate chronological and morphological groups.
Naturally acquired genetic variation caused by isolation and small population numbers, along with artificial cranial deformation (Brown 198l) , can account for the morphological pattern evident in the late Pleistocene cranial material from Australia.
The range of morphological variation (not just overall size) of late Holocene cranial material is reduced compared to that of the earlier skeletal sample. This could be due to a major reduction in isolation of groups because of a substantial increase in the population of the continent. After the last glacial maximum population numbers would have gradually increased. This increase is especially evident (archaeologically visible) during the Holocene (see Habgood 1991 for references).
In its simplest terms, this population increase (repopulation may be more accurate) would mean more people and/or groups inhabiting the landscape, which would have greatly reduced the isolation of groups and significantly increased gene flow between them. As population numbers and densities increased, gene flow would have been higher, introducing new genetic material and or changing gene frequencies in the previously isolated groups.
The trend would have been for gradually increasing differentiation within the individual groups, which previously had unique morphologies, until all groups displayed similar types and ranges of variation. The genetic and morphological variation within the various groups (except possibly those from previously well populated areas such as the Murray Valley) would have increased whereas the continent wide range of variation would have decreased because there would have been a reduction in the occurrence of groups with unique morphologies. Unique morphologies would have disappeared and the chance of new ones becoming fixed would have been greatly lessened in possibly larger-sized groups. Added to this would have been the cessation of artificial cranial deformation in the Murray Valley as detailed in the Brown monograph.
Instead of having relatively homogeneous groups forming a very heterogeneous continental population, as one had during the late Pleistocene, there would have been heterogeneous groups making up a more homogeneous continental population (similar range of variation within groups). As noted above, the overall range of morphological variation would also have reduced.
This is not to say that the modem Australian Aborigines are morphologically homogeneous, for they display a high degree of variation both within and between regions (Kirk l98l), but the range of variation is reduced compared to the earlier skeletal sample. This suggests that the unifying influence of gene flow was not total and that other genetic processes were still acting upon the populations.
There may, however, have been a change in the pattern described above prior to contact. Groups living in resource-rich areas that supported high population densities appear to have had rigid territorial boundaries and short marriage distances, therefore restricting gene flow (see Habgood 1991 for references). In arid regions with low population densities and unpredictable resources, groups maintained more fluid boundaries and extensive social networks, which would have promoted gene flow (see Habgood 1991 for references).
These patterns most probably came into existence with repopulation after the last glacial maximum. That is, when groups moved back into and permanently occupied arid regions they took with them extensive social networks, and as population densities reached critical levels in regions such as the Murray River corridor (Webb 1984), more rigid territorial boundaries became necessary to maintain control of resources. This change may have influenced the morphological range of more recent Aboriginal crania, but would not affect the pattern of the late Pleistocene and earlier Holocene material.
I have diverged somewhat from a review of the two monographs. However, one of the major benefits of these works is the information they contain which should stimulate further debate on population biology within Australian prehistory, such as the preceding discussion.
Both volumes are well illustrated and have excellent and informative maps, diagrams, graphs and extensive tables. The raw material provided within the monographs will be as useful as the descriptions and conclusions reached. One can only hope that the publication of the Lake Mungo skeletons and WLH 50 is of as high a quality as these two monographs and is completed in the very near future.
Brown, P. 1981 Artificial cranial deformation: a component in the variation in Pleistocene Australian crania. Archaeology in Oceania 16:156-67.
Brown, P. 1987 Pleistocene homogeneity and Holocene size reduction: The Australian human skeletal evidence. Archaeology in Oceania 16:41-67.
Habgood, P.J. 1985 The origin of the Australian Aborigines: An alternative approach and view. In P.V. Tobias (ed.) Hominid Evolution: Past, Present and Future. New York: Alan R. Liss, pp.367-80.
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Habgood, P.J. 1986b The origin of the Australians: A multivariate approach. Archaeology in Oceania 2 1:130-7.
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Habgood, P.J. 1992The origin of anatomically modern humans in east Asia In G. Brauer and F.H. Smith (eds) Continuity or Replacement: Controversies in Homo Sapiens Evolution. Rotterdam: A.A. Balkema, pp.273-88.
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Thorne, A.G. 1976 Morphological contrasts in Pleistocene Australians. In R.L. Kirk and A.G. Thorne (eds.) The Origin of the Australian, pp.95-112.Canberra: AIAS.
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Review of 'The Willandra Lakes Hominids’ by S.G. Webb and ‘Coobool Creek. A Morphological and Metrical Analysis of the Crania, Mandibles and Dentition of a Prehistoric Australian Human Population’ by Peter Brown
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