Archive | Nigerian Archaeology RSS feed for this section

Evolutionary Thoughts

7 Apr

I’m currently writing an essay on the origins and definitions of Anatomically Modern Humans (Homo sapiens species), and it is an endlessly fascinating (and confusing!) topic.  Recent finds and reports have complicated the picture but have also opened up the delightful hominin evolutionary line (Jurmain et al 2011).  It is also necessarily a wide ranging subject with researchers pinpointing various features of AMH throughout the palaeoanthropological record (Jurmain et al 2011, Pettitt 2005, Tattersall & Schwartz 2008).  By seperating out the modern skeletal anatomymodern behavioural characteristics and genetic information as they appear in the fossil and archaeological record, it is my view that this approach highlights the ever changing nature of what it means to be a modern human.  This triad approach allows the investigator to realise that different aspects of what is typically expressed as AMH traits (Tattersall & Schwartz 2008: 50), whilst taken as a whole, can also be expressed at differing times due to several factors.

From our earliest anatomically modern traits described in the crania of Omo Kibish 1 & 2 from 195,000 years ago (Pettitt 2005), to cultures and symbolic behaviour attributed to populations throughout Africa by 100,000 years ago, and the evidence of the first dispersals of AMH out of Africa around 80,000-60,000 years ago (Wood 2005), it is clear that AMH have spread far beyond their homeland.  However the continuing work of researchers in Africa and elsewhere in the world has also highlighted the rentention of archaic features in certain AMH populations; examples include the intriguing Iwo Eleru crania found in Nigeria (Harvatie 2011, and Dienekes’ Anthropology post here) and the recently described Chinese skeletal remains reporting a complex evolutionary history of East Asian AMH (Curnoe et al 2012).  This can be attributed to various reasons, such as the admixture of those AMH with archaic hominids or population isolation.

Recent email communication with my friend and fellow blogger Confusedious has also highlighted the varied genetic changes in recent populations of Homo sapiens.  His excellent post on gene culture coevolution is a detailed and elegant essay discussing rapid and modern genetic changes in H. sapiens regarding disease loading in populations, gene expression and selective gene adaptation; largely as a result of agricultural uptake and increased population density (Barnes et al 2011, Hawks et al 2007).  Recent molecular work on the origin of TB (Smith et al 2009 & previously wrote about here by me) has helped highlight the need for a nuanced approach in treating the disease in modern populations.  Examples include indigenous Papua New Guinea people and the Torres Strait Islanders, who do not have a genetic history of coevolution with the disease from the practise of intense animal husbandry, and who are now threatened by today’s demographic pressure and population expansion of those who do, and who have selectively adapted to it (Barnes et al 2011).

In conclusion, the gestalt of the Homo sapiens species may be instantly recognizable to some (Tattersall & Schwartz 2008), but there are a number of factors that intertwine, such as skeletal morphology, genetic change and behavioural adaptations, that produce a species that emerged roughly 200,000 years ago and are continuing in their adaptations to this world.

Bibliography:

Barnes, I., Duda, A., Pybus, O. G. & Thomas, M. G. 2011. Ancient Urbanization Predicts Genetic Resistence to Tuberculosis. Evolution. 65 (3): 842-848.

Curnoe, D., Xeuping, J., Herries, A. I. R., Kanning, B., Tacon, P. S. C., Zhende, B., Fink, D., Yunsheng, Z., Hellstrom, J., Yun, L., Cassis, G., Bing, S., Wroe, S., Shi, H., Parr, W. C. H., Shengmin, H. & Rogers, N. 2012. Human Remains from the Pleistocene-Holocene Transition of Southwest China Suggest a Complex Evolutionary History for East Asians. PLoS ONE. 7 (3): 1-28. e31918. doi:10.1371/journal.pone.0031918

Harvati, K., Stringer, C., Grun, R., Aubert, M., Allsworth-Jones, P., & Folorunso, C. A. 2011. The Later Stone Age Calvaria from Iwo Eleru, Nigeria: Morphology and Chronology. PLoS ONE. 6 (9): e24024. doi:10.1371/journal.pone.0024024

Hawks, J., Wang, E. T., Cochran, G. M., Harpending, H. C. & Moyzis, R. K. 2007. Recent Acceleration of Human Adaptive Evolution. Proceedings of the National Academy of Sciences. 104 (52): 20753-20758.

Jurmain, R., Kilgore, L. & Trevathan, W. 2011. The Essentials of Physical Anthropology, International Edition.Belmont:Wadsworth.

Pettitt, P. 2005. ‘The Rise of Modern Humans’. In Scarre, C. (ed) The Human Past: World Prehistory & the Development of Human Societies. London: Thames & Hudson. pp 124-175.

Smith, N. H. Hewinson, R. G. Kremer, K. Brosch, R. & Gordon, S. V. 2009. Myths and Misconceptions: The Origin and Evolution of Mycobacterium tuberculosisNature Reviews: Microbiology. Vol 7: 537-544.

Tattersall, I. & Schwartz, J. H. 2008. The Morphological Distinctiveness of Homo Sapiens and Its Recognition in the Fossil Record: Clarifying the Problem. Evolutionary Anthropology. 17: 49-54.

Wood, B. 2005. Human Evolution: A Very Short Introduction. Oxford: Oxford University Press.

Updates…

8 Sep

Apologies for the lack of updates; please bear with me.  I’ve had a busy past few weeks & the future doesn’t look any less busy! Preparation for moving down to start the Msc Human Osteology & Funerary Archaeology program at the University Sheffield have begun, but I’m still on the look out for a lab coat!  I move to the city shortly, but I’m still enjoying the time I have left in my hometown.  This year has flown by a bit too quickly!

The next Skeletal Series update will concern the human hip bones, and their form and function.  They are particularly key in both age and sex diagnosis of the individual.  I’ll also shortly start a brief write-up of the German Grampus placement & the activities we got up to, since I’ve finally just got round to finishing their report for the program online.

I did manage to read my way through Waldron’s (2009) ‘Palaeopathology’  manual whilst I was in Germany, and what a delight it was too! I’d highly recommend reading it, especially if you are going to be working with human bones from archaeological sites.  I have a feeling that this book, and the Human Bone Manual, will not be far from my side in the next few months.  ‘Palaeopathlogy’ offers ‘Operational Definitions’ which help to improve the diagnosis of disease in ancient human remains via clinical definitions and backgrounds. I would say this is a must have, especially since a lot of the palaeopathogical literature cannot be cross examined due to the differences in rational & criteria used.

A quick scan of BBC’s online news website reveals that a late stone age skull discovered from Iwo Eleru in Nigeria has some interesting ‘primative’ features associated with human evolution.  The online article can be found here at PLoS online.  The article deals with the chronology and morphology of the Iwo Eleru calvaria.  This is a very interesting article as it deals with a skull that shows similar morphological features present in archaic homo sapiens humans around 100,000 years ago but its found in a  context that is dated to around 15,000BP.  It is also rare that human remains are found during this date in West Africa.  The article states that this cranium fragment represents ‘evidence of deep population substructure in Africa and complex evolutionary processes for the origin of modern humans’, that the archaic homo sapiens didn’t just cut off after Anatomically Modern Humans (AMH) appeared.  Frankly, I think this also highlights what is often forgotten in the prehistoric & palaeolithic archaeological record.  It is not just migration out of Africa and the dispersal of AMH that is fascinating and interesting, but also to still keep looking and researching inside Africa to see the evolutionary and populational changes still concurrent with human expansion elsewhere.

I also noticed the other that over at John Hawks’s weblog he has announced the Malapa Soft Tissue project.  This project aims to discover if soft tissues from an ancient hominid has been preserved from the Malapa site cave site, just outside Johannesburg in South Africa.  Recently discussed in the National Geographic magazine, the hominids discovered at this site are believe do to be Australopithecus Sediba, a possible intermediate form between the Australopithecus & Homo genus.  Much information remains to be gleamed from these exciting and relatively complete finds.  Up to date information on the MST project can be found on the John Hawks link.  Perhaps one of the most interesting aspects of this project is that is it open access science; you are encouraged to take a part and offer your expertise!  Keep an eye on it and see where it leads…

I’ll be back shortly.

Further news on A. Sediba