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The Wonders of Easter Island: A BBC Documentary

2 Feb

I have been pleasantly surprised by the great many documentaries aired on the BBC Four channel that focus on archaeology, perhaps none more so than a recent series entitled Lost Kingdoms of South America.  Presented by the knowledgeable and engaging Dr Jago Cooper, the series explored various (and to me some unknown) cultures in the pre-Colombian continent.  I admit to having a great interest in Mesoamerican and South American archaeology, as such it was a delight to watch these detailed documentaries.

Therefore I was quite happy to come across another BBC 4 feature the other day, this time with a focus on Easter Island (here-after Rapa Nui), a tiny Pacific volcanic island well-known for the megalithic human moai statues that dominate the landscape and the birdman cult that super-ceded the creation of the statues (Lipo et al 2013).  For a previous undergraduate essay I had researched the island’s history so I was familiar with the ecocide theory, the tale of the island’s supposed descent into war/ruin after using up the majority of the island’s natural resources.  However this documentary discovered a far more nuanced tale to tell.

easterislandmap

Geographic location of Easter Island, one of the most isolated inhabited islands in the world. Annexed by Chile in 1888, the island remains a special territory of the country. The aboriginal habitation of the island from Polynesian populations is hypothesized to have been in the mid 1st millennium AD (700-1100), although dates vary widely (Chapman 1997). The pre-European contact population maximum is thought to have been around 14,000 individuals, although post 1722 (the year Roggeveen landed) the aboriginal population greatly diminished and fluctuated due, in part, to slavery exploitation, the introduction of new diseases and repeated famines. The modern population currently stands at around 5800. (Image credit: Eric Gaba 2008).

Once again presented by Dr Jago Cooper, an archaeologist and curator at the British Museum, the 90 minute documentary was an interesting and informative show.  It was a pretty comprehensive overview of the history of the people of Rapa Nui, discussing their somewhat still mysterious origins (Chapman 1997) right through to the issues that dominate the island to this day.  It was also a show that actively engaged with a wide range of current specialists on the history and archaeology of the island.  It detailed not just the controversial theories of the island’s ecological diversity decline, but also the range and depth of archaeological research conducted on an island that has captivated and captured the hearts of many.

I am not going to review the whole program here but I do want to highlight a few parts where, for me, the program really came alive with the great value that archaeology has to offer.

Ecology and Landscape at Rapa Nui

The ecology and landscape environment of Rapa Nui have undergone extensive changes throughout the human habitation of the island, perhaps none more so than in the last 400 years.  Visitors to the island today will note the largely steppe like appearance of the landscape – the only trees still standing can largely be found around the main settlement of Hanga Roa in the south-west of the island.  The island was previously heavily forested with trees, shrubs and ferns.  The main predominate tree of the forested island was the now extinct palm tree Paschalococos disperta (Rapa Nui palm), which disappeared from the environmental record around 1650.  It is important to note that while there are various extinction events of various flora and fauna (land-birds such as herons and parrots) throughout the island’s natural history, there seems to be a fairly major change in landscape and ecology in the middle of  the 2nd millennium AD (Chapman 1997).

Although there are many theories on the collapse of the ecology of the island (from over-population, the various causes of intense deforestation and the impact of invasive species) it is likely thought that a combination of these and other factors were involved.  It is not my intent here to discuss this but to highlight the implications of this in the archaeological record.

The loss of the forests that covered Rapa Nui has led to some serious consequences in the landscapes ability to hold minerals and water in the soil.  The Roggeveen expedition of 1722, at least a century after the extinction of the main palm trees, stated that Rapa Nui was exceptionally fertile in its soil quality, that the population successfully cultivated sweet potatoes, bananas and sugar cane.  Further expeditions in the 18th century repeated claims of fairly well fed individuals.  This is interesting as we have archaeological and palaeoenvironmental evidence of a decrease in the ecological flora typically ascribed to a sub-tropical Polynesian environment.

The program shed light on this topic in a few surprising ways.  Firstly there are numerous caverns throughout Rapa Nui, some of which have carved artwork and glyphs attributed to different tribal groups.  Some, however, were clearly used as agricultural areas to help grow banana crops and sweet potatoes.  Further to this there was also evidence of lithic mulch across the island, that at least some of the forest chopped down was to make way for agricultural plots of land.  This, for me, was a new term I had not come across before.  It is the laying stones (of varying sizes, but in this case just under football size) across the landscape in small plots of lithic mulch gardens or in larger areas to encourage more nutrients into the soils and stabilize the landscape.

easterisnaldrocks

Dr Jago Cooper, some rocks and a horse.  The process of using lithic-mulch to help grow food produce has been used in countries throughout the world, and it is a distinct process though one that can be overlooked. (Image credit: BBC).

This encourages the retention of minerals and water in the soil below encouraging plant growth and helps to increase  the crop biomass and overall yields.  The stones also help to decrease/stop the rate of soil erosion from wind or water run off and shadow the soils from direct sunlight whilst also producing an environment which encourages other vegetation to grow (Lightfoot & Eddy 1994: 425).  Lithic mulch gardens have been noted at a variety of archaeological sites across the world that occur in predominately dry environments (Anasazi and Hohokam sites in Arizona, Negev in Israel, Maori in New Zealand etc) (Lightfoot & Eddy 1994: 426).

Inevitably the ecology and landscape has changed due to the actions of the human populations, both from those that are aboriginal and those that visited the island post-European contact.  Perhaps most damaging to the island soil ecology was the widespread grazing of over 70,000 sheep in the early 20th century, helping to destabilize the soils which has led to intense soil and field erosion ever since.

 The Moai and the Ahu Platforms

The moai are the quite wonderful sculpted megalithic stone statues, made mostly of volcanic tuff, that dominate the island.  They are largely found on either ahu platforms in groups or dotted around inland individually (termed road statues).  They are largely quarried from the main site of Rano Raraku on the foothills of the Terevaka volcano, the highest point on the island.  Around 887 statues have been documented and recorded so far, with almost 50% of them still located in and around Rano Raraku in a variety of completed states (Lipo et al 2013).  The statues were created over a 500-600 year period in the early part of the 2nd millennium AD, although exact dates are not known.

The smoothed statues are known for their overly large heads and minimal stylistic appearance that are carved in flat planes.  With an average height of 4 meters and width of 1.6 meters, the statues weigh in at 12 tonnes on average, although there are exceptions and some are often rather larger and heavier.  Some statues also have pukao, either hats or hairstyles, that adorn the top of the statue heads, which can weigh many tons themselves.  Although nearly every statue recorded is in a standing pose there is one statue that shows a kneeling position, Tukuturi at Rano Raraku, that also has a beard – a highly unusual feature of the statues and reminiscent of other Polynesian societies.  It is thought that this individual was carved late in the statue phase.          

easterislandahu

The Rapa Nui moai, with one of the individuals ‘wearing’ a pukao. Note the ahu stone platform on which the statues are standing on, and the fairly desolate landscape behind the statues. There is evidence to believe that the statues, or at least some of them, had been painted over in a variety of colours with coral and stone insets for eyes.  During the Birdman cult era glyphs were also added to some of the statues (Image credit: BBC).

A number of the statues are found on the ahu fitted stone ceremonial platforms that can be found around the whole perimeter of the island.  Nearly every ahu platform faces inland – there is only one documented case where the statues face out towards the sea.  It is thought that the statues represent the chiefs of ancestors of the aboriginal population, with the individuals facing inland towards their respective tribal land (Lipo et al 2013).  Researchers have also noted the boundary motifs of tribes on some moai throughout the Rapa Nui island, suggesting that fairly individual identities existed (Chapman 1997), regardless of their ancestral origin (Stefan 1999).  The ahu platforms consist of carefully fitted stone sections with distinct stone wings to the side of the platform and stone fields out to the front of the platform.

The documentary highlighted the fact that it is likely a variety of methods were used to transport the statues to their respective sites. There was a pretty impressive part where it was highlighted that the statues could walk to site:

easterislandwalking

Noted in the oral tradition of the native Rapa Nui population, the walking of the statues to their site could have been possible as Lipo et al. (2013) demonstrated with their smaller size replica statue in some rather interesting experimental archaeology. Wooden rollers and other methods of transportation have also been discussed. (Image credit: BBC).

Lipo et al. (2013) have stated that wear marks on the torso and heads of the statues indicate that great pressures were hinged at these areas suggesting that the size, shape and centre of gravity of the statues all point towards a rocking motion to gather the momentum to walk the statues.

After the initial contact with European sailors following Roggeveen’s landing in 1722 (in which the moai were still standing) it was reported that the toppling of the statues had commenced, with almost no statues standing on the ahu platforms by 1868.  It has been postulated by some researchers and historians (Lipo et al. 2013) that the statues were thrown down with force by rival tribal bands, but others have pointed out that at least some of the statues were carefully placed face down.  What is known is that some of the ahu platforms where the statues are face-down also function as ossuaries or burial complexes.  Today a total of 50 moai have been placed back in the standing position, whilst a few have been shipped to institutions are the world (Lipo et al. 2013).

For further information on the Moai I’d recommend checking out an ongoing project entitled Easter Island Statue Project, co-directed by Jo Anne Van Tilburg and Cristián Arévalo Pakarati, whose homepage can be found here.  A detailed map of the moai on the ahu platforms on the island can be found here.

Human Osteology and Population Origin

I think it is pertinent to touch on here a few of the (few) human osteology studies that have been carried out on aboriginal skeletal material of the Rapa Nui.  It has long been argued by some early archaeologist, such as Thor Heyerdahl, that Rapi Nui and other Polynesian islands were settled by Native Americans.  Although some archaeologists concede that contact between Native Americans and Polynesians was feasible (Chapman 1997: 161), the majority of the osteological and genetic tests carried out on human skeletal material indicates a Polynesian origin for the aboriginal inhabitants of Rapa Nui (Chapman 1997, Chapman & Gill 1998, Stefan 1999).

Chapman & Gill (1998: 189) measured the stature of 92 individuals from the Rapa Nui aboriginal population (54 males and 38 females from prehistoric (A.D. 1680-1722) and protohistoric (A.D. 1722-1868) populations.  The individuals were taken from the various tribal populations on the island and the bones (in ranked order: femur, tibia, fibula, humerus, radius or ulna) were measured and analysed using a regression formula devised for New Zealand Maori populations (Chapman & Gill 1998: 189).  The results stated that there was no statistical difference between the tribal areas of the island and stature, male average was 1726 mm and 1595 mm for females, reflective of general sex dimorphism (Chapman & Gill 1998: 191).  The stature range was found to be within range of other Polynesian groups and there were no obvious differences in stature within the population of the Rapa Nui island.

OLYMPUS DIGITAL CAMERA

Measuring a right humerus with an osteometric board and a calculator. Stature estimation is a vital technique in bioanthropology to gauge the height of past populations (useful guide here, image credit: Paul Duffy at Aberdeen Council).

Stefan (1999) and Chapman’s (1997) studies both indicate that the initial aboriginal population of Rapa Nui were from Polynesian origins.  Stefan’s (1999) studied 50 cranio-facial measurements on the crania of  prehistoric/protohistoric Rapa Nui populations and discovered greater between-group homogeneity in males than females but not the population as a whole.  Chapman (1997: 171) study does highlight the need to thoroughly investigate the prehistoric and protohistoric populations genetically for any further population admixture and genetic drift from later populations, with the need to specifically sample individuals from each main geographic location of the island.  As far as I am aware I do not know of any stable isotopic work that has been carried out on the skeletal remains, but this could add another informative dimension to understanding the Rapa Nui culture (1).

It must also be remembered  the island was repeatedly visited (and raided) after Roggeveen’s first landing by European ships in the same century, which ultimately led to a rejection of all ships by the Rapa Nui.  During the 19th century Peruvian ships also repeatedly and successfully made slave raids on the island, capturing up to a thousand aboriginals to work in the mines in Peru.  The slave raids, but also the introduction of new diseases from the Europeans and from surviving miners, caused the aboriginal population to dramatically fall resulting in an aboriginal population of only 111 individuals at one point in 1877.  Although a historic low, the population had undergone fluctuation before but probably never to this dramatic extent.  The documentary state that around half of the modern population (around 2500 individuals) claim to be genetically related to the original aboriginal population.

The program also produced a succinct point by highlighting the ongoing struggles of Rapa Nui to become recognised as an independent island.  There are still many controversies surrounding the Rapa Nui culture and as highlighted above there is still little agreement on certain key points of the population history of the island and the ecological effects that this produced.

Conclusion

Although only briefly mentioned here it is worth noting that Rapa Nui has evidence for a rich and diverse culture.  Interestingly Forment et al. (2001) highlight the fact that the wooden carvings of human figures, known as moai kavakava, were being carved and produced in the same period as the terminal phase of the megalithic statues.  Also noted is the fact that the wooden carvings probably do not indicate accurate physical reflections of the population (Forment et al. 2001: 532) as some researchers have suggested.  There are also numerous petroglyphs present throughout the island as well as an apparent script called rongorongo, which included glyphs of geometric and pictographic images (Chapman 1997).  Although Rapa Nui is only 15 miles by 7 miles in size, it has produced an incredibly diverse cultural legacy and material culture.  This is echoed today by the living population who understand the very real threat of population collapse and remain intent to keep their culture, and cultural heritage, alive.

Notes

(1). If I am mistaken (I only did a quick literature search) please email me or drop a comment below.

Important Update 25/10/14

New genomic evidence has shown that the human population of Rapa Nui had contact with the Native American populations from around AD 1300-1500.  The genome wide study of 27 native Rapa Nui individuals has discovered that there was significant contact between the inhabitants of Rapa Nui and Native American populations from around 19 to 23 generations ago.  The evidence for European based population admixture dates from around AD 1850-1895.  This is an outstanding piece of news, please see the Past Horizons article for more information.  The 2014 Current Biology article can be found here.

Further Information

Bibliography

Chapman, P. M. 1997. A Biological Review of the Prehistoric Rapanui. The Journal of the Polynesian Society. 106 (2): 161-174. (Open access). 

Chapman, P. M. & Gill, W. G. 1998. Estimation of Stature for the Prehistoric/Protohistoric Rapanui. The Journal of the Polynesian Society. 107 (2): 187-194. (Open access).

Forment, F., Huyge, D. & Valladas, H. 2001. AMS 14C Age Determinations of Rapanui (Easter Island) Wood Sculpture: Moai Kavakava ET 48.63 from Brussels. Antiquity. 75: 529-32. (Open access via academia).

Lightfoot, D.R. & Eddy, F.W. 1994. The Agricultural Utility of Lithic-Mulch Gardens: Past and PresentGeoJournal. 34 (4): 425-437. (Partially open access).

Lipo, C. P., Hunt, T. L. & Haoa, S. R. 2013. The ‘Walking’ Megalithic Statues (Moai) of Easter IslandJournal of Archaeological Science40 (6): 2859-2866. (Abstract only).

Stefan, V. H. 1999. Craniometric Variation and Homogeneity in Prehistoric/Protohistoric Rapa Nui (Easter Island) Regional Populations. American Journal of Physical Anthropology. 110 (4): 407-419. (Abstract only).

News: Amazonian Archaeology & Oldest AMH In SE Europe (Ukraine)

23 Jun

Amazonian Archaeology

Recently there has been a fantastic series on British Television called Unnatural Histories.  One episode in particular focuses on the Amazon rainforest and its past.  If you live inside Britain you can watch it here on BBC Iplayer.  If not, its called Unnatural Histories Episode 3: Amazon, please let me know if you find it elsewhere.

It details the history of the Amazon rainforest from 3 particular angles; the modern environmentalist perspective, the modern day people who live there and it also includes recent Pre-Columbian archaeological findings from ancient sites situated along the Amazon river.  Of particular interest are the massive amounts of earthenwork Geoglyphs being found alongside the Amazon river, and beyond in the forest.  Roughly dating from around AD 100 up until AD 1300, these monuments range in size, from the small to the sublime.  Sadly, these are often uncovered after the effects of deforestation.  The geogylphs are often found without many clues as to their function with little material remains associated with the sites, although they are most likely socio-religious meeting points.  Very interestingly, archaeologists have found numerous ‘roads’ which link up various sites.  At other sites alongside the river, mounds had been built up in which Pre-Columbian peoples lived atop of during the flooding seasons.

Brazilian Geoglyphs In The Amazon Rainforest

This is particularly exciting to me, as during my undergraduate degree course, very little archaeologically was said on the vast expanse of land that the Amazon extends over in South America.  This was in direct contrast to the vast tracts of archaeology that litter the dry, mountainous western side of that continent (Tinwanaku, Huari, & Inca civilizations etc).  The last 15 minutes of the show are fascinating as the sites found recently keep piling up, and as it also juxtapositions the past populations onto a map of the modern populations.  It is well worth a watch.

Oldest SE European Anatomically Modern Humans Found In The Ukraine

In other news, a recent PLoS ONE article discusses human and faunal remains from a Middle and Upper Palaeolithic site located in the Crimea, Ukraine.  This site has the earliest evidence of AMS dated modern Homo Sapiens, and also includes some very interesting mortuary practices.  The site is perfect as it has securely dated stratigraphy, distinct geological boundaries, alongside an impressive use of the multidisciplinary approach in its investigations and conclusions.

I will shortly write up a proper review on this entry.  In the meantime, the article can be found here:

Prat et al. 2011. The Oldest Anatomically Modern Humans from Far Southeast Europe: Direct Dating, Culture and Behavior’

Skeletal Series Part 5: The Human Rib Cage

6 May

As we covered the vertebrae in the previous post in the skeletal series, we shall move on to the last elements in the axial skeleton (bar the clavicle and scapula in next post).  The elements of the appendicular skeleton will follow shortly.

Excavation

As before, great care must be taken when excavating the ribs.  I have carried out micro-excavation of juvenile remains, (when I volunteered at Humber Field Archaeology) that consisted of the vertebrae, half of the ribcage and parts of the pelvis in-situ, and it took a while.  During excavation of human remains on site, it is very unlikely that the rib cage will be in its natural anatomical position.  Due to the soil and weight of the earth above the body, and the movement in the intervening period between burial and excavation, the ribs are likely to be broken and misplaced.  As always keep a look out for finer skeletal finds.

The Rib Cage

The focus of this post will be the sternum, which is made up of the Manubrium, Corpus Sterni (or Gladiolus) and the Xiphoid Process alongside a look at the ribs, all of which help to form the rib cage.  It is necessary to note here that variation in the number of ribs, as of the vertebrae discussed previously, can differ in people and in archaeological populations (Mays 1999: 15).  The function of the rib cage, as the main upper part of the torso in the human body, is to protect the vital organs that lie within the protective enclave of the ribs.  They include the majority of the torso organs such as the heart, liver, lungs, kidneys and partially the intestines.  The rib cage also helps breathing by the function of the intercostal muscles lifting and lowering the rib cage, aiding inhalation and exhalation.  The ribs are attached dorsally to the vertebrae, with articulating facets for the tubercle end of the ribs for the thoracic vertebrae (White & Folkens 2005).

Main anatomical elements of the rib cage. (Image credit: Wikipedia 2011).

Rib Cage Anatomy, Terminology and Elements

The number of ribs present in the typical human skeleton is of 12 paired rib elements (a total of 24 altogether). Ribs project from proximal articulating facets with thoracic vertebrae, slant forward, and depending on the rib pair under consideration, articulate at the distal end with either the sternum, hard cartilage or ‘float’ freely (Jurmain et al 2011).  Ribs usually increase from size from rib 1 to rib 7, and decrease in size from rib 7 to rib 12 (White & Folkens 2005: 185).

Posterior view of ribs and their articulating vertebrae partners. (Image credit: Wikipedia 2011).

The Upper 7 ribs on each side of the cage connect distally directly to the sternum via cartilage, whilst the 8th, 9th and 10th ribs connect indirectly to the sternum.  The last 2 ribs are often called ‘floating’ ribs because they have ‘short cartilaginous ends that lie free in sides of the body wall’ (White & Folkens 2005: 181).

The basic landmark anatomy of a rib includes the head, neck, tubercle which articulates with the thoracic vertebrae & the long shaft of the rib.  In the picture below the head of the ribs are medial whilst the sternal ends are lateral.  The side that is superior is called the cranial edge, whilst the inferior is called the caudal edge.  It can be fairly easy to side a loose or partial rib as the Cranial edge is fairly thicker and blunter when compared to the grooved and sharp caudal edge (White & Folkens 2005: 192).

The rib cage laid out from 1st to 12th ribs, note the size and shape morphology. Occasionally an individual will have only 11 paired ribs or may have an extra pair, this is natural variation. (Image credit: Shutterstock).

Distinctive Rib Cage Elements

  • The 1st rib is most unusual and can usually be identified the easiest.  It is particularly blunt, broad and thick, as well as this it has no caudal groove (Roberts & Manchester 2010).
  • The 2nd rib serves as an intermediary to the 1st and 3-9th more regular ribs.  It has a large tuberosity for the serrator anterior muscle half way along its length (White & Folkens 2005: 187).
  • The 11th rib lacks a tubercle and the sternal end is often pointed.
  • The 12th rib is shorter then the 11th rib and may be even shorter then the 1st rib.  It lacks the angle and costal groove, and is often easy identifiable (May 1999).

Sternum

As stated the sternum is made of 3 individual bones, those of the manubrium, corpus sterni and the Xiphiod Process.  As made clear by the diagrams below, there are 7 facets located laterally for the anterior of the ‘true’ ribs alongside the corpus sterni and manubrium.  The sternum is composed of these three elements in adulthood but develops from 6 segments (White & Folkens 2005: 181).

The manubrium is the thickest and squarest part of the sternum bones and should be easily identifiable as such.  At the superior corners there are clavicular notches located, which articulates with the right and left clavicles.  The clavicles and scapula help to form the shoulder girdle and will be discussed in the next post.

The three individual elements of the sternum, with the manubrium (proximal), corpus sterni (centre) and xihoid process (distal) highlighted. (Image credit: Wikipedia 2011).

Lateral view of sternum elements with the individual rib facets highlighted. (Image credit: Wikipedia 2011).

The corpus sterni is rather thin in comparison to the manubrium, and it is often said to be ‘bladelike’.  Again, costal notches are present as seen in the above picture.  They cater for ribs 2-7 (Mays 1999).

The xiphoid process can be found inferior to the corpus sterni but, depending on the age of the person involved, may not be found in archaeological samples.  The process shares the seventh costal notch.  This bone is often highly variable in shape, and is late to ossify (White & Folkens 2005: 184).

A Pre-contact Peruvian Case Study

The site of Pacatnamu, in the Jequetepeque River valley on the northern Peru coast, provides a site where mutilated human remains and contextual information has been unearthed (Larsen 1997: 137).  At this Moche site (100-800 AD), evidence has been found of executed captives who were thrown into a trench at the bottom of an entrance to a ceremonial precinct (Verno 2008: 1050).  The skeletal group found & studied was composed of 14 adolescent and young adult males, who were recovered from 3 superimposed layers at the site.  The superimposed layers were indicative of 3 distinct burial episodes (Larsen 1997: 137).  From the evidence on the skeletal elements, it seems that weathering took place after death but before burial.  The evidence is backed up by the palaeoenvironmental remains of the presence of the pupal cases of muscoid flies (Verano 1986).

Pacatnamu mass burial archaeological site and the second layer (Image credit: Verano 2008).

It seems that the display of the decomposing bodies, together with a lack of a proper burial, was clearly intentional.  In the topmost layer of the burial episodes, multiple stab wounds were found on both the vertebrae and rib elements.  This pattern is broken by the bottom and middle layer where the pattern is more towards decapitation or throat slashing as evidence by cutmarks on the cervical vertebrae (Larsen 1997: 137).  Of particular interest is the evidence of five individuals from the middle and lower deposits that have bisected manubriums with evidence of fractured ribs, which is suggestive of the chest cavity being opened forcibly (Verano 1986).

Larsen (1997: 137) remarks that on the ‘basis of the age distribution, sex, and evidence of healed and unhealed injuries (rib fractures, depressed cranial fractures), Verano (1986) speculates that they were war prisoners’.   The conclusion is well supported from the cultural representations in the art and architecture of the Moche culture.  Many cultures throughout the world made, and continue to make, sacrifices of various kinds; in particular it is thought that for pre-contact South American cultures human sacrifice represented ‘the most precious form of sacrifices, and seems to have been reserved for particularly important rituals and events’ (Verano 2008: 1056).  It has also been noted that the capture and killing of enemies was a common practise in communities in pre-contact South America.  Such killings can also incur within ritual presentations and displays.  There are many such examples throughout South American, and indeed throughout the Americas (Teotihuacan, Punta Lobos, Sipan) (Verano 1986).  A careful consideration through the integrated studies of the archaeological sites, bioarchaeological study of the human material, together with careful ethnographic comparisons, can help to understand the processes and results of human sacrifice in South American cultures.

Further Information

Bibliography:

Jurmain, R. Kilgore, L. & Trevathan, W.  2011. Essentials of Physical Anthropology International Edition. London: Wadworth.

Larsen, C. 1997. Bioarchaeology: Interpreting Behaviour From The Human Skeleton. Cambridge: Cambridge University Press.

Mays, S. 1999. The Archaeology of Human Bones. Glasgow: Bell & Bain Ltd.

Roberts, C. & Manchester, K. 2010. The Archaeology of Disease Third Edition. Stroud: The History Press.

Verano, J. W. 1986. ‘A Mass Burial of Mutilated Individuals at Pacatnamu‘. In C. B. Donnan & G. A. Cock. (eds.) The Pacatnamu Papers. 1. pp.117-138. Los Angeles: Museum of Cultural History, University of California.

Verano, J. W. 2008. ‘Trophy Head-Taking and Human Sacrifice in Andean South America. In H. Silvermann & W. Isbell.(ed.) Handbook of South American Archaeology. pp.1045-1058. Los Angeles: Springer.

White, T. & Folkens, P. 2005. The Human Bone Manual. London: Elsevier Academic Press.