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The Trials and Tribulations of Homo floresiensis: A Quick Introduction

1 Sep

I haven’t wrote about palaeoanthropology much recently, but I have been meaning to write about Homo floresiensis for a while now.  The diminutive hominin, most likely a new Homo species although this is still debated, was discovered by chance on the Indonesian island of Flores in 2003 during the excavation of the Liang Bua cave site, which was led by the now sadly deceased New Zealand archaeologist Mike Morwood (Brown et al. 2004).  The team that excavated at Liang Bua cave found the remains for a probable 12 separate H. floresiensis individuals dating from around 95,000 years ago to around 13,000 years ago (1), making H. floresiensis one of the last hominin species to live in conjunction with our species, H. sapiens (Brown et al. 2004: 1055).  One of the most complete individuals found at the site is LB1, an adult female aged around 30 who has almost both lower limbs, upper right arm, pelvis and cranium surviving (see image below).  It is this individual that has become the holotype, or type species, for H. floresiensis and on who most of the current research has, and continues, to focuses on (Brown et al. 2004, Brown 2012, Falk et al. 2005, Henneburg et al. 2014).

The majority of this research has been focused on the skeletal remains themselves and archaeological context as attempts to extract ancient DNA (aDNA) from the remains has not been successful, likely due to the cave environment that the skeletons were excavated from and the fragmentary nature of the surviving aDNA.  Morwood’s team formally announced the details of the skeletal remains in 2004 and stated that the remains included primitive and derived features resulting from long term isolation and endemic dwarfing (Brown et al. 2004: 1055-56).  It is important to note here that up until the excavation of H. floresiensis in 2003 it was thought that only H. erectus and H. sapiens were the only Homo hominins present in Late Pleistocene Asia (Brown et al. 2004: 1056).  Later hominin finds, such as at the Denisova Cave excavations in Siberia in 2010 and the announcement of the Denisovan species, have highlighted that other unknown hominins were present in Late Pleistocene Asian contexts helping to fundamental change, and challenge, the way that we think of the evolution of our species H. sapiens (Reich et al. 2010: 1053).

LB1

The species holotype is LB1, found in 2003 in the Liang Bua cave site on Flores, Indonesia. The adult female individual dates to 18,000 years old, stood 3.5 ft tall and represents one of the most complete H. floresiensis individuals found. Notice the large dentition relative to the overall cranium size. Image is not to scale. Image credit: Jennifer Clark (Human Origins Program) and Chip Clark (Smithsonian Institution).

There are many issues surrounding the remains of the H. floresiensis hominins that serve to obstruct and help obfuscate the research that has taken place into understanding the origin and anatomy of the floresiensis hominin.  Inevitability this is ongoing as McVie (2014) highlights in a recent Guardian newspaper article.  Thus it is pertinent to highlight them here to help understand where we are at with understanding the remains of the Flores hominin.  Indeed the H. floresiensis case has all the unfortunate tropes of a spectacular palaeoanthropological find (2) (the unexpectedness of the finds, the bickering academics, mishandling of remains etc.) and continues to show no sign of abating.

As is indicative above, H. floresiensis is a unique and interesting recent hominin ancestor, even more so as the only physical remains of the species are the 12 individuals found and excavated at the Liang Bua cave site in Indonesia.  It is the opposite to our modern notion of the (much maligned) Neandertal, being gracile, petite and small in statue and body.  Perhaps inevitably it was labelled a ‘hobbit’ species (although this word has led to problems with the Tolkein estate).  The type specimen LB1 was quickly repudiated as a H. sapiens individual with a pathology by several researchers and others who have, at various times, stated that all the H. floresiensis individuals, and in particular LB1 and partial skeleton LB6, display attributes varying from myxoedematous endemic cretinism (Oxnard et al. 2010, Brown 2012), Laron Syndrome (Falk et al. 2009, see Hawks 2007), or Down Syndrome (Benton 2014, Henneburg et al. 2014).  There have also comparisons even being made of the singularity of the Late Pleistocene epoch species being compared to the K/T impact boundary event 65 million years ago (Eckhardt et al. 2014), which frankly is a little mystifying.

McVie (2014) has highlighted a potential conflict of interest with regards to both the Eckhardt et al. (2014) and Henneburg et al. (2014) publications, as there is a suggestion that Henneburg (who helped author both articles) picked his reviewers to help favour his research team’s hypothesis and investigation.  The journal that both of the articles were recently published in, Proceedings of the National Academy of Sciences of the United States of America (or PNAS), does not operate a peer review policy in the recognised sense, as most of the other respected journals use, but uses its own specific and trusted system (see here).  Perhaps most surprising is the fact that this team have now published 3 separate papers each focusing on different pathological conditions each time in their continued belief that the H. floresiensis remains are probable members of H. sapiens and represent pathological processes (Henneburg et al. 2014).

Regardless of the ongoing new-species-or-not debate there must be further investigation of the context of the remains.  As Hawks (2007) highlights it is the exact nature of where H. floresiensis fits in both the evolutionary tree and the archaeological context of Asia that remains to be thoroughly demonstrated.  This can only be determined by further finds with consolidated archaeological contexts over an extensive period of time and, with luck, further specimens of this hopeful new species.  The specimens of this population found on Flores, Indonesia, are both tantalising for the human evolution implications and frustrating for their apparent uniqueness in location and time.  As such the Flores H. floresiensis remains are surely one of the most interesting and divisive points of interest in the palaeoanthropological world today.

Notes

(1). A new analysis of the chosen radiocarbon samples and the stratigraphy of the cave site by Sutikna et al. (2016) has led to a serious revision in the chronology of the Homo floresiensis fossils.  It seems that all fossil evidence of H. floresiensis is older than 60,000 years, which is a major revision and leaves a lot of questions regarding the contextual material culture and faunal remains and their association with the fossil hominins.  John Hawks has covered the implications that this new article by Sutikna et al. has in a detailed and interesting read, check it out here.

(2). An excellent counter example of this is the University of the Witwatersrand and National Geographic funded Rising Star project currently underway in South Africa, where the remains of a spectacular palaeoanthropological site (with the evidence of numerous hominin individuals of some importance) has been well and truly open to researchers and members of the public to take part in and to learn about.  This has included an extensive and on-going social media presence and an open call for researchers to join collaborative workshops to study the remains.

Lean More

  • The Smithsonian Institute has a handy guide in introducing the hominins of human evolution at the Human Origins website and, as a part of this, there is a nice guide to H. floresiensis.
  •  For a full round of the issues involved in the research of H. floresiensis and the LB1 type fossil, I highly recommend reading the Wikipedia entry on the species which covers all pertinent academic articles published.

Bibliography

Benton, A. 2014. Was the “Hobbit” a Human with Downs Syndrome? Probably Not. EvoAnth. Accessed 19/08/14. (Open Access).

Brown, P. 2012. LB1 and LB6 Homo floresiensis are Not Modern Human (Homo sapiens) Cretins. Journal of Human Evolution. 62 (2): 201-224.

Brown, P., Sutikna, T., Morwood, M. J., Soejono, R. P., Jatmiko, Wayhu Saptomo, E. & Rokus Awe Due. 2004. A New Small-Bodied Hominin from the Late Pleistocene of Flores, IndonesiaNature. 431 (7012): 1055–1061.

Eckhardt, R. B., Henneburg, M., Weller, A. S. & Hsu, K. J. 2014. Rare Events in Earth History Include the LB1 Human Skeleton from Flores, Indonesia, as a Developmental Singularity, not a Unique Taxon. PNAS. 111 (33): 11961-11966. (Open Access).

Falk, D., Hildebot, C., Smith, K., Morwood, M. J., Sutikna, T., Brown, P., Jatmiko, E. W. S., Brunsden, B. & Prior, F. 2005. The Brain of LB1, Homo floresiensis. Science. 308 (5719): 242-245.

Falk, D., Hildebolt, C., Smith, K., Jungers, W., Larson, S., Morwood, M., Sutikna, T., Jatmiko, E. W. S. & Prior, S. 2009. The Type Specimen (LB1) of Homo floresiensis Did Hot Have Laron Syndrome. American Journal of Physical Anthropology. 140 (1): 52-63.

Hawks, J. 2007. Another Diagnosis for a Hobbit. John Hawk’s Weblog. Accessed 24/08/14. (Open Access).

Henneberg, M., Eckhardt, R. B., Chavanaves, S. & Hsu, K. J. 2014. Evolved Developmental Homeostasis Disturbed in LB1 from Flores, Indonesia, Denotes Down Syndrome and Not Diagnostic Traits of the Invalid Species Homo floresiensis. PNAS. Early View: 1-6. (Open Access).

McKie, R. 2014. Homo floresiensis: Scientists Clash Over Claims ‘Hobbit Man’ was Modern Human with Downs Syndrome. The Guardian. Accessed 19/08/14.

Oxnard, C., Obendorf, P. J. & Kefford, B. J. 2010. Post-Cranial Skeletons of Hypothyroid Cretins Show a Similar Anatomical Mosaic as Homo floresiensis. PLoS ONE. 5 (9): 1-11. (Open Access).

Reich, D., Green, R. E., Kircher, M., Krause, J. Patterson, N., Durand, E. Y., Viola, B., Briggs, A. W. & Stenzel, U. et al. 2010. Genetic History of an Archaic Hominin Group from Denisova Cave in Siberia. Nature. 468 (7327): 1053–1060. (Open Access).

Sutikna, T., Tocheri, M. W., Morwood, M. J., Saptomo, E. W., Awe, R. D., Wasisto, S. … & Storey, M. 2016. Revised Stratigraphy and Chronology for Homo floresiensis at Liang Bua in Indonesia. Nature. In Press. doi:10.1038/nature17179.