Professor Maciej Henneberg's claims about the teeth of Homo floresiensis (the Hobbit)
“But now LB1’a first lower left molar had assumed mind-blowing significance. Maciej’s experience as a dental assistant had led him to interpret unusual characteristics spotted on the tooth’s crown as indicating endodontic work had been carried out by a modern dentist using a drill and cement filling, while the Hobbit was still alive.”
Henneberg M, and Schofield J. 2008. The Hobbit Trap : money, fame, science and the discovery of a 'new species'. Kent Town, S. Aust.: Wakefield Press, p.p. 76.
In a popular book he has written with a retired journalist (Henneberg and Schofield 2008, chapter 4), and in claims that he has recently made to journalists at scientific meetings, Professor Maciej Henneberg (Department of Anatomy, University of Adelaide) has stated that the type specimen of Homo floresiensis may have evidence of modern dental work in the left first mandibular molar. He has used this claim in an attempt to cast dispersion on the peer reviewed research conducted at Liang Bua, undermine the status of H. floresiensis, and promote his own poorly informed views (Jacob et al. 2006; Henneberg et al. 2015). When discovered there was no evidence of dental work in the Pleistocene hominin skeletal materials from Liang Bua (Brown et al. 2004). There is also absolutely no evidence of dental caries in the mandibular canines and premolars of LB1, as re-stated in a more recent claim by Henneberg and colleagues in an unsupported conference abstract (Henneberg et al. 2011).
The teeth of LB1, and to a lesser extent LB6, are heavily worn, with dentine exposed on the chewing (occlusal) surfaces (Morwood et al. 2005), without dental fillings and dental caries (Brown and Maeda 2009). Professor Henneberg is either extremely inexperienced with the way teeth wear in hunter-gatherers and earlier hominins, has taken the advice of someone similarly poorly informed, did not examine the teeth in adequate detail, or is being dishonest and playing on the limited experience of his co-authors (Robert Eckhardt, Julia Gretsky, Stefan Flohr). If any of these circumstances apply then I would have thought that the prudent approach would be to carefuly verify your claims before talking to the media, or putting your thoughts in a book or conference abstract (Henneberg, et al, 2011). The presence, or absence, of a dental filling, or dental caries, is easily verifiable. Either one is present, or it is not. If there is not a filling then there are implications for the credibility of Professor Henneberg, particularly in relation to his observations and stated expertise. My personal experience is that I have worked with collections of teeth (hunter-gatherer, Neolithic and more recent humans, a variety of hominins and non-human primates) in Australia, Asia, Europe, UK and North America over the last 30 years. Teeth were an important part of my PhD research (1979-1982) and I have maintained my interest, and increased my experience, in the following years. I cleaned the teeth of LB1 using brushes and soft probes, while wearing magi glasses. Grain-by-grain, it was a delicate and slow process. There was no filling in the crown of the mandibular left first molar, or any other teeth. The mandibular teeth of LB1 were described in detail by Brown and Maeda (2010) and dental restoration, of any type, are not present. Most recently, my conclusions about the absence of modern dental work in LB1 were independently confirmed by Jungers and Kaifu (2011).
In hunter-gatherer populations, for instance indigenous Australians prior to European contact, there was often minimal premasticatory preparation of foods (cooking), and the abrasive content of food (dust, dirt, grit) may also have been high. As a result teeth wore very quickly, and 6-7 years after a tooth had erupted and reached occlusion it was not unusual for the enamel crown to be worn through on the cusps and underlying dentine exposed (Campbell 1939; Molnar 1971; Molnar and Molnar 1990; Murphy 1959; Richards and Miller 1991; Smith 1984). Dentine is softer than enamel and once exposed, the tooth crowns wear more quickly, with the dentine eventually forming a slightly cupped surface surrounded by a ridge of enamel. As wear starts to approach the pulp canals, odontoblast cells in the pulp may start to deposit secondary dentine, filling in some of the pulp chamber and preventing infection. However, rates and extent of occlusal wear may still exceed this secondary dentine deposition, and the pulp be exposed. Secondary dentine typically has a different appearance to primary dentine, forming a darker circle on the exposed occlusal surface. Depending upon occlusion, crown morphology, variations in the eruption and development schedule of individual teeth and the masticatory habits of individuals, there can be considerable variation in the extent of occlusal wear between a tooth on one side of the dentalarch and its antimere on the other.
In skeletal materials from archaeological sites the enamel and dentine in teeth tend to be a slightly different colour. Dentine is more porous, has a higher organic content, does not reflect light as readily as more crystalline enamel, and may take up mineral and organic materials from the archaeological deposit more readily. Where there is a lot of manganese in the soil dentine, and bone, are usually stained a dark brown, in limestone caves dentine stays a chalky white. In other words, both at original inspection and in photographs, you can distinguish between enamel and dentine. Where the enamel is worn to the thickness of a few microns it is semi-transparent and looks different to exposed dentine and thicker enamel at the margins of the tooth. A further complication with archaeological materials is that the post-depositional environment can adversely effect the preservation of enamel and dentine, most commonly erosion, decalcification, chips, scratches, and colour change. Expertise is required to distinguish the results of taphonomic processes from how the teeth appeared during life. All too easy for the inexperienced, or those with a particular bias, to mistake postdepositional damage for evidence of pathology.
Evidence of the way teeth wear, and the appearance of occlusal surface enamel and dentine, is provided by museum collections of hominin and Palaeolithic human skeletons. The examples provided below come from the collection of the South Australian Museum, a few kilometres from Professor Henneberg's Adelaide office. Most of the larger museums around the planet have collections of similar material, and there is a very large scientific literature on tooth wear in pre-urban humans and early hominins (try Google scholar). For each of the images there is a link to a high resolution (300 dpi) version.
What about Liang Bua Homo floresiensis?
Professor Henneberg has told the media, for instance http://www.theaustralian.news.com.au/story/0,25197,23561788-30417,00.html and http://www.sciam.com/article.cfm?id=flores-hobbit-root-canal, that he is concerned about discolouration he sees on the occlusal surface of the left mandibular first molar of LB1. He has suggested that this may be a temporary filling inserted into this tooth, when LB1 was alive in the 1930's. In other words he is disputing that LB1 died 18,000 years ago. A temporary filling as an amalgam would be more obvious, and he thinks that a temporary would more closely match the colour of the occlusal surface of the tooth. Professor Henneberg has suggested to journalists that I missed the presence of this filling as my research was too hasty and lacking sufficient care. For the record I have spent more than six weeks with the Liang Bua material in Jakarta, and several years with the records (casts, ct scans, radiographs, photographs, etc) in my laboratory. Professor Henneberg spent only a couple of days with parts of the Liang Bua collection after it had been removed to the late Professor Teuku Jacob's laboratory at Gadja Mada University. According to Professor Henneberg's account, shortly after the dental treatment LB1 subsequently died and a 5.5 m deep hole was dug in the cave to bury her. Ignoring the evidence from the stratified archaeological deposit which demonstrates that a 5.5 m deep grave was not dug into the cave, Professor Henneberg's claims can easily be tested with observations of the tooth in question. High resolution (150 & 300 dpi) copies are linked to the images below, all are copyright Peter Brown. See also the high resolution ct slices in Jungers and Kaifu (2011), see below.
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Micro-CT scan of the three left mandibular molars in LB1 Homo floresiensis (Jungers and Kaifu 2011). As was apparent in the published visual descriptions (Brown and Maeda 2009), there is no evidence of dental restorations in the crown of the left M1, as stated by Maciej Henneberg and co-authors. |
Conclusion
There is absolutely no support for Professor Henneberg's claim of a filling (1930's dental restoration) in the crown, or roots, of the left mandibular first molar of LB1. Dr Alan Thorne, one of Professor Henneberg's supporters has stated to journalists that if Henneberg's claims are correct then there are implications for Homo floresiensis http://www.theaustralian.news.com.au/story/0,25197,23561788-30417,00.html . Of course the reverse should also be true. As the claim is a complete fabrication, without any substance, then there are implications for the credibility of Professor Henneberg and his supporters.
Peter Brown, April 2008
Update, February 2011
Most recently, Jungers and Kaifu (2011) have examined Henneberg and Schofield's claim for a dental restoration in the crown of the left mandibluar M1 of LB1. They conclude
“Our findings corroborate and extend the primary conclusions reached earlier by Brown (2008) and Brown and Maeda (2009). Photographs, a digital radiograph, and micro CTs scans of the left molars of LB1 all reveal no evidence of a dental filling in the left M1.Occlusal wear and white mineral staining of the exposed dentine were confused by Henneberg and Schofield (2008) for a dental filling, but all teeth of LB1 with exposed dentine exhibit comparable degrees of chalkiness. The pulp cavity and the root canals of the tooth were never breached in life and exhibit no evidence of endodontic treatment.”
References
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Brown P, Maeda T. 2009. Liang Bua Homo floresiensis mandibles and mandibular teeth: a contribution to the comparative morphology of a new hominin species. Journal of Human Evolution 57: 571-596.
Campbell TD (1939) Food, food values and food habits of the Australian Aborigines in relation to their dental conditions. Aust J Dent 43:1-15, 45-55, 73-87, 141-156, 178-198
Henneberg, M. Schofield, J. 2008. The Hobbit trap. Wakefield Press, Adelaide.
Henneberg M, Gretsky J. Eckhardt, R.B, Flohr, S. 2011. Dental evidence bearing on morphological dating of the LB1 specimen. Am. J. Phys. Anthropolo 144, 160.
Henneberg M, Eckhardt, RB, Chavannaves S, Hsu, KJ. 2015. Evolved developmental homeostasis disturbed in LB1 from Flores, Indonesia, denotes Down syndrome...PNAS 111 (33) 11967-11972.
Jungers, WlL. and Kaifu, Y. 2011. On dental wear, dental work, and oral health in the type specimen (LB1 )of Homo floresiensis. Am. J. Phys. Anthropol. 145, 282-289
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Smith BH (1984) Patterns of molar wear in hunter-gathers and agriculturalists. American Journal of Physical Anthropology 63:39-56