Category Archives: Science

Integrating Phytoliths within Use-Wear/Residue Studies of Stone Tools

Archaeological Context:

The obsidian artefacts came from two sites, FRL and FAO, located in West New Britain Province, Papua New Guinea. These sites are notable for having well-defined stratigraphy and relatively long time depth. The Bitokara Mission Site (FRL) was excavated by Specht (1988). The FAO excavations were part of the larger Garua Island Project (Torrence et al, in press). Both sites have a sequence of volcanic tephras with a well-developed soil in the upper horizon of each. The volcanic events have been dated by radiocarbon. The tephras have been sourced and cross correlated by macroscopic and geochemical techniques.

Stratigraphic units have been divided into four chronological periods:

  • Older than W-K1 tephra (10,000 – 6000 BP)
  • Between W-K1 and W-K2 tephra (5900 – 3600 BP)
  • Between W-K2 and Dk tephras (3600 – 1100 BP)
  • Post-Dk tephra (1100 BP – present)

Organic preservation of macroscopic plant material is poor due to the high acidity of soils and high rainfall, but organic residue on stone artefacts was not unexpected because phytoliths are extremely resistant to decay.

Methodology:

  • 10 artefacts taken haphazardly from each arbitrary unit of 1m x 1m grid during excavation, using a metal trowel so that they were not handled in any way. With adhering soil, artefacts placed into plastic bags, air-dried, sealed and stored.
  • Analysis began with microscopic examination. Use-wear and residues assessed concurrently using high and low magnification.
  • To distinguish from post-depositional contamination, integrated analysis of residues with four main kinds of use wear is required. These are:
    • Scarring
    • Rounding
    • Polish
    • Striations
  • Surface preservation of the obsidian tools and residues present was recorded.
  • Phytoliths identified by comparison with reference collection.
  • Integrity of residue on artefact tested by comparing phytolith assemblage on surface with that of surrounding soil. If residue due to usage then there should be differences.

Results:

  • Phytolith assemblages included wide variety of grasses falling mainly within Bambusoideae and Panicoideae sub-families, herbaceous types (Compositae, Marantaceae, Cyperaceae), diverse arboreal types (Palm, Moraceae, Musaceae, Burseraceae, Annonaceae, etc) and unknown Dicotyledon types.
  • The analysis of starch grains, often from plants that do not make phytoliths (e.g. Root crops such as taro and yams), expand our knowledge of plant use. The authors were surprised to note the survival of these given the aggressive techniques of phytolith extraction. The only current explanation is that the grains were silicified in some way.
  • In a number of examples the phytolith data provided additional information on the types of plants which produced the use-wear.
  • The earliest Periods 1 and 2 appear to have been characterised by both multi-functional and single purpose tools primarily for processing starch. Hafting was common, but unretouched flakes were also used on soft, starchy plants.
  • Period 3 is characterised by change to more expedient tool use.
  • By period 4 this trend has progressed further. In the majority of cases the very sharp, unretouched obsidian flakes were grasped with bamboo leaves. There is no evidence for starch processing in this period. This is important as ethnographic accounts only refer to uses such as shaving. Shell not stone tools used in the recent past for processing starchy tubers.

Reference:

Kealhofer, L, Torrence, R and Fullagar, R. 1999. Integrating Phytoliths within Use-Wear/Residue Studies of Stone Tools. Journal of Archaeological Science 26: 527-546.

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Heritage Of A Deadly Disease Pinpointed With Help From Iceland’s Genealogical Database

A collaboration of scientists from Iceland and the United States has used Iceland’s genealogical database* to trace the ancestors of patients suffering from hereditary cystatin C amyloid angiopathy (HCCAA). Analysis shows that the deadly mutation in the cystatin C gene, L68Q, derives from a common ancestor born roughly 18 generations ago, around 1550AD.

This dominantly inherited disease, which is due to a mutation in cystatin C (L68Q), strikes young adults with healthy blood pressure. The disease results in death from repeated brain haemorrhages, on average by the age of 30. The origin of the mutation causing HCCAA was previously unknown, but using DNA haplotype analysis* the scientists have shed light on the history of this autosomal dominant disease that has high penetrance in contemporary Icelanders.

The scientists found that 200 years ago, obligate carriers of the mutation lived a normal life span compared to the control population (their spouses). In carriers born around 1820, however, a trend of shortening life span began, resulting in an average life span of only 30 years in people born around 1900. This 30-year lifespan has stayed constant since then in both men and women.

At the same time, a matrilinear effect appeared whereby those who inherited the mutation from the mother died earlier. For carriers born after 1900, the difference is a loss of 9.4 years for those who inherited the mutation from their mothers rather than their fathers. Based on this information, the authors propose that the traditional diet of the nation (which in the past consisted largely of whey-preserved offal as well as meat, dried fish, and butter) “protected” the mutation carriers for almost 300 years until the Icelandic diet changed early in the early 19th century, exemplified by drastic increases in imported carbohydrates and salt.

This finding has implications for studies of Alzheimer’s disease as cerebral amyloid angiopathy (CAA) is almost universally found in Alzheimer’s patients and normal cystatin C protein is one of the proteins found in amyloid in brains of Alzheimer’s patients. Studies are underway to try to elucidate the risk factors with the hope of providing a preventive stategy for cystatin L68Q carriers.

*By deCODE Genetics

Palsdottir A, Helgason A, Palsson S, Bjornsson HT, Bragason BT, et al. A Drastic Reduction in the Life Span of Cystatin C L68Q Carriers Due to Life-Style Changes during the Last Two Centuries. PLoS Genet, 4(6): e1000099 DOI: 10.1371/journal.pgen.1000099

The Mystery of Mass Extinctions Is No Longer Murky

If you are curious about Earth’s periodic mass extinction events such as the sudden demise of the dinosaurs 65 million years ago, you might consider crashing asteroids and sky-darkening super volcanoes as culprits. However, a new study, published June 15, 2008, in the journal Nature, suggests that it is the ocean, and in particular the epic ebbs and flows of sea level and sediment over the course of geologic time, that is the primary cause of the world’s periodic mass extinctions over the past 500 million years.

The Boneyard – Edition #18

Welcome to the 18th edition of the Boneyard, the blog carnival devoted to all things palaeo, from dinosaurs to pollen to hominids and everywhere in between.

We begin this latest edition in the Middle Palaeolithic with Julien Riel-Salvatore of ‘A Very Remote Period Indeed’ who discusses the interpretation of a new isotopic study of Neanderthal diet, based on material from a Neanderthal tooth from the French Middle Paleolitihic site of Jonzac.

A little further back time, we find Tim Jones at ‘Remote Central‘ discussing Pre-Clovis Humans in the Oregon High Desert, whilst at the same blog Terry Toohill puts ‘Human Evolution on Trial – North to Alaska’.. Meanwhile, here at Archaeozoology, we examine the later evolution of Pleistocene Horses in the New World.

We move into the Tertiary period with Emile of ‘The World We Don’t Live In‘ who discusses The oreodonts: the tylopods successful venture. Meanwhile, Brian Switek at ‘Laelaps‘ describes the ‘Truly Terrifying Entelodonts’ of the Early Miocene and Oligocene. In the same blog we also find a tale of another fearsome predator, this time of the middle Eocene: the Bad Cat from Wyoming, the largest meat-eating mammal from what would become the Wind River Formation.

Travelling back into the Mesozoic, we have two blogs about the ever-popular topic of dinosaurs. Darren Naish of ‘Tetrapod Zoology‘ talks about the land ‘Where the scelidosaurs and iguanodontians roam’, whilst GrrlScientist at ‘Living the Scientific Life (Scientist, Interrupted)‘ reviews ‘What Bugged the Dinosaurs? Insects, Disease and Death in the Cretaceous’ by George Poinar, Jr., and Roberta Poinar.

David Hone of ‘Archosaur Musings‘ brings us a series of three posts on the Early Triassic pterosaur Raeticodactylus filisurensis: part one describes the pterosaur, part two introduces Rico Stecher, the man behind Raeticodactylus, and part three is an interview with Rico about his work. Also from the Triassic comes the story of enigmatic hellasaurs, some of the most important insect fossils in the world from the Madygen Formation of Kyrgyzstan, courtesy of ‘microecos‘.

Reaching the Permo-Triassic boundary we find Peter Ward discussing ‘Suspending Life’ in Seed magazine; If almost every species on Earth was killed some 250 million years ago, how did our ancient ancestors survive and evolve into us?

We take a look at ancient plant-life with Christopher Taylor of ‘Catalogue of Organisms‘ as he tells us about Prototaxites, one of the Giants of the Silurian.

Dinochick, meanwhile, brings us more proof that only money speaks in a discussion of the recent news about fossils for sale.

We finish on a lighter note with Zach of ‘When Pigs Fly Returns‘ and Spinodracus dysonii, the porcupine dragon.

Thanks go to everyone who contributed to this edition of the Boneyard. The next edition will be hosted by Familiarity Breeds Content on May 3rd.

Pleistocene Horses in the New World

The later evolution of horses can be problematic and this is perhaps best illustrated in the Americas, where more than 50 species of Pleistocene equids have been named, most of them during the 19th and early 20th centuries (Weinstock et al., 2005: 0001). Whilst it has been argued that this number should be drastically revised, no consensus has as yet been reached about the number of valid species or their phylogenetic relationships (Weinstock et al., 2005: 0001). It was to address this problem that a recent study by Weinstock et al., looked at a segment of between 349 and 716 base pairs of the mitochondrial control region of fossil equid remains from a number of different localities in North and South America and Eurasia ranging in date from c. 53,000 years ago to historical times (Weinstock et al., 2005: 0002).

Using maximum likelihood, phylogenetic analysis resolved Hippidion, New World ‘stilt-legged’ horses (NWSL) and caballines (including the domestic horse, Equus caballus, and the extant wild Przewalskii horse) as three genetically divergent species within a monophyletic group (Weinstock et al., 2005: 0002). African zebras and asses and Asian asses (onager and kiang) form a basal polytomy (Weinstock et al., 2005: 0002). However, the close phylogenetic relationship between Hippidion and caballine horses is in direct contrast to palaeontological models of hippidiform origins (Weinstock et al., 2005: 0002; Benton, 1997: 342).

It is suggested that the origin of Hippidion should not be seen as a descendent of Miocene pliohippines; instead, its origins appear to be more recent, probably during the last stages of the Pliocene (c. 3 Ma), which is close to the time of the first fossil occurrence of this genus (Weinstock et al., 2005: 0003). This is in opposition to views expressed by authors such as McFadden (1997) who claim that hippidiforms (genera Hippidion and Onohippidium) were present in North America as early as the late Miocene (c. 7 – 8 Ma).

The situation with the phylogenetic position of the NWSL is also apparently resolved with the molecular evidence, which places them as North American endemics tather than Eurasian migrants (Weinstock et al., 2005: 0003). Specimens from both north (Alaska/Yukon) and south (Wyoming/Nevada) of the Pleistocene ice sheets clearly belong to the same taxon. This apparent large geographic distribution raises the possibility that other Late Pleistocene NWSL currently described as different species (E. francisci, E. tau, E. quinni, E. cf. hemionus, E (Asinus) cf. kiang) may in fact represent the same taxon (Weinstock et al., 2005: 0003). Their origins probably lie south of the Pleistocene ice sheets, where Mid-Pleistocene remains (c. 0.5 Ma) with similar limb characteristics have been found (Weinstock et al., 2005: 0003). Frequencies of NWSL are much lower in the north and they appear to have a restricted temporal distribution. It would appear that, despite their presence in eastern Beringia (unglaciated Alaska/Yukon), they failed to disperse through the Bering land-bridge into western Beringia (north-east Siberia) (Weinstock et al., 2005: 0003).

All caballine horses from western Europe to eastern Beringia – including the domestic horse – would appear to be a single Holarctic species (Weinstock et al., 2005: 0003). This group can be split into two major clades. The first is broadly distributed from central Europe to North America north and south of the ice. The second clade appears to have been restricted to North America. If present in the Old World at all, it would appear to have disappeared before domestication of the horse took place, around 5,000 years BP, as all domestic horses cluster in the first clade (Weinstock et al., 2005: 0004).

Reference:

Benton, MJ. 1997.Vertebrate Palaeontology. Second Edition. London: Chapman and Hall.

McFadden, BJ. 1997. Pleistocene horses from Tarija, Bolivia, and the validity of the genus Onohippidium (Mammalia: Equidae). Journal of Vertebrate Palaeontology 17: 199-218

Weinstock, J, Willerslev, E, Sher, A, Tong, W, Ho, SYW, Rubenstein, D, Storer, J, Burns, J, Martin, L, Bravi, C, Prieto, A, Froese, D, Scott, E, Xulong, L, and Cooper, A. 2005. Evolution, systematics, and phylogeography of Pleistocene horses in the New World: a molecular perspective. PLoS Biology 3 (8): 0001-0007.

The Boneyard – Submissions Reminder

The next edition of the Boneyard blog carnival will be hosted here at Archaeozoology on April 19th so please get your palaeontology submissions in to me by the end of the week.  The email address to send things to is silverthorn AT bardicweb DOT com or you’re welcome to leave a link in the comments.

How long can TB survive?

A note on the environmental persistence (or otherwise) of Mycobacterium tuberculosis in 300-year-old Hungarian mummies can be found over at MicrobiologyBytes.