Major Bioanthropology Research Projects

The Contribution of South Asia to the Peopling of Australasia

Professor Colin Groves and Dr David Bulbeck
ARC Discovery Grant 2002-2006

This project focuses on the human fossil record from three regions critical to understanding the origins of our species, Homo sapiens. Australia is crucial in view of its diverse array of ‘gracile’ and ‘robust’ human remains of Late Pleistocene/early Holocene age. Equally important are South and Southeast Asia as they lined the tropical route between Africa, our species’ Late Pleistocene homeland according to the Out of Africa theory, and Australia. Osteological and archaeological evidence of the selection pressures that operated in earlier hunter-gatherers will be employed to explain the observed patterns of morphological evolution throughout the study region.

Dr Pathmanathan Raghavan was Senior Research Associate until mid-2005 and currently continues his involvement as a Visiting Researcher. Three PhD students in the school, Messrs Nimal Perera Daniel Rayner and Michael Westaway, are conducting research essential to the project.

See Bulbeck, Rayner, Groves and Raghavan 2003. ‘The contribution of South Asia to the Peopling of Australasia’ and the relevance of Basel’s Naturhistorisch Museum anthropological collection to the project aims. Bulletin der Schweizerische Gesellschaft fur Anthropologie 9: 49-70.

The Flores Hobbit – Homo Floresiensis or Microcephalic Eastern Indonesian?

Dr David Bulbeck and Dr Marc Oxenham
ARC Discovery Grant 2006

The announcement by Brown et al. (2004; Morwood et al. 2005) of a new species of Homo, which survived on the island of Flores in Indonesia till as recently as 13,000 years ago, is rightly hailed as one of the most remarkable discoveries ever in palaeoanthropology. The hominin’s minute stature (1 metre for the type specimen, Liang Bua 1), diminutive cranial capacity (415 cc), and survival till a time well after Homo sapiens had spread across Australasia, have stunned the scientific community. However, almost immediately after the official announcement, an alternative explanation sprang up, claiming that the type specimen was a modern human with microcephaly – a rare genetically based pathology that severely curtails the growth of the brain and stunts the individual’s growth. The specialist debate published so far has focused on craniometrics, and brain growth and development, including studies of endocasts that are claimed to support or refute the microcephaly hypothesis (Falk et al. 2005; Weber et al. 2005). (We are also aware of a wider range of issues being canvassed at the time of writing, but we shall desist from discussing them here as the relevant works are still in press or in preparation.)

Our project takes a different approach by studying features which, if associated with microcephaly, would be associated as secondary features, and which may well be entirely independent of brain size development. Brown and Morwood (2004), in their vigorous response to the microcephaly hypothesis, claim that Liang Bua 1 (along with other remains assigned to the species) expresses a suite of features that are absent from Homo sapiens, pathological or otherwise. The main examples of these features are: Tomes’ root on second lower premolar, molariform lower first premolar, rotated upper second premolars, anterior narrowing of the lower tooth row, posterior slope of the mandibular synthesis with complete absence of any chin, superior and inferior tori crossing the posterior surface of the mandibular synthesis, very large mandibular ramus relative to the corpus, a large fissure between the mastoid process and the petrous crest, a recess between the tympanic plate and the entoglenoid pyramid, a smooth tabular surface to the petrous pyramid, and a constricted foramen lacerum. To this impressive list of claimed, non-sapient characters can be added further traits that occur only infrequently in H. sapiens, such as a Tomes’ root on the first lower premolar, and multiple mental foramina. Postcranial peculiarities of the Liang Bua 1 type specimen further include relatively elongated arms and lack of humeral torsion.

However, can we be certain that these characters are entirely absent from microcephalic individuals and from eastern Indonesian Homo sapiens? Osteological studies of microcephaly are few and far between, and certainly have not extended to recording details of the morphology of the dentition, mandibular symphysis, cranial base, or postcranial anatomy. Similarly, the osteological documentation of recent eastern Indonesians is essentially restricted to craniometric comparisons (Pietrusewsky 1984) and some limited dental observations. If we could find a microcephalic eastern Indonesian, it would be possible to compare its features with those claimed for Homo floresiensis, to directly test the microcephalic hypothesis. No such specimen is known, however, so the only means to simulate such a test is to integrate (1) a “cross-racial” anatomical description of the secondary effects of microcephaly with (2) a description of the occurrence of the claimed H. floresiensis characters on eastern Indonesians. If the characters listed by Brown and Morwood (2004) are associated neither with microcephaly nor with eastern Indonesian anatomy, the microcephalic hypothesis would be falsified, perhaps fatally so; if on the other hand there is a tendency for these features to occur with microcephaly and amongst eastern Indonesians, the microcephalic hypothesis would have survived a falsification test.

Most of the known microcephalic specimens are of Europeans, and so our project has focused on European comparisons; in particular, the large collection at the Musée de l’Homme in Paris. However, we are also studying microcephalic skulls of a South African (Bradford University), a Mauritian of suspected African ancestry (Peabody Museum), two prehispanic Peruvians (Peabody and Smithsonian Institute), a New Caledonian (Musée de l’Homme), a South Indian (Royal College of Surgeons, London), an Egyptian and a Sri Lankan (British Museum of Natural History, London). During 2006 we shall also make comparable observations on non-microcephalic skulls from all of the populations represented by microcephalic specimens, as well as samples of eastern Indonesians (including prehistoric Flores burials represented by postcranial as well as cranial elements – Sukadana 1984; van der Plas 2002), to evaluate the microcephaly hypothesis.

Our observations will by no means be limited to the list of H. floresiensis characters identified by Brown and Morwood (2005), for two main reasons. First, our study may reveal further characters specifically relevant to microcephaly or to the morphology of eastern Indonesians, of benefit to these research areas as well as the specific hypothesis tested by the project. Secondly, a wide menu of measurements and morphological observations will provide a statistical context of observations for evaluating the discriminatory weight that should be assigned to the features specifically linked to microcephaly (or the morphology of Liang Bua 1). This latter point is in anticipation of the statistical analyses to be carried out on our results, including cladistic analysis, logistic discrimination, and multivariate analysis including principle coordinates analysis and linear discrimination analysis.

Acknowledgments

We gratefully thank the following curators who have facilitated our access to relevant museum collections: Philippe Mennecier (Musée de l’Homme), Jo Buckberry (Bradford University), John de Vos (Natural History Museum, Leiden), Olivia Herschensohn (Peabody Museum of Archaeology and Ethnology), David Hunt (American Museum of Natural History), Robert Kruszynski (British Museum of Natural History), and Simon Chaplin and Martyn Cooke (Royal College of Surgeons, London).

References

Brown, P., T. Sutikna, M.J. Morwood, R.P. Soejono, Jatmiko, E. Wahyu Saptomo and Rokus Awe Due, (2004), A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia, Nature 431:1055-61.

Brown, P. and M. Morwood, (2004), Comments, Before Farming 2004/4 article 1. http://www.waspress.co.uk/journals/beforefarming/journal_20044/news/2004_4_01.pdf

Falk, D., C. Hildebrot, K. Smith, M.J. Morwood, T. Sutikna, P. Brown, Jatmiko, E.W. Saptomo, B. Brunsden and F. Prior, (2005), The brain of LB1, Homo floresiensis, Science 308:242-45.

Morwood, M.J., P. Brown, Jatmiko, T. Sutikna, E.W. Saptomo, K.E. Westaway, Rokus Awe Due, R.G. Roberts, T. Maeda, S. Wasisto, and T. Djubianto, (2005), Further evidence for small-bodied hominins from the Late Pleistocene of Flores, Indonesia, Nature 437:1012-17.

Plas, M. van der, (2002), A New Model for the Evolution of Homo sapiens from the Wallacean Islands, Leiden University Biology Department undergraduate program paper, to be published online in PalArch.

Sukadana, A., (1981), Peninggalan manusia di Liang Bua dan hubungannya dengan penemuan di Lewoleba dan Melolo, Berkala Bioantropologi Indonesia 1, S. 53-72.

Weber, J., A. Czarnetzi and C.M. Pusch, (2005), Comment on “The brain of LB1, Homo floresiensis”, Science 310:236b.