bones

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3-Million Year Old Fossilised Metacarpals Show Evidence of Tool Use.

A recent study has put forward some important evidence of early human ancestors, in particular Australopithecus africanus, wielding tools in a human like fashion dating around 3 to 2-million years ago.

Figure 1: A recent study has put forward some important evidence of early human ancestors, in particular Australopithecus africanus (pictured), wielding tools in a human like fashion dating around 3 to 2-million years ago.

Figure 1: A recent study has put forward some important evidence of early human ancestors, in particular Australopithecus africanus (pictured), wielding tools in a human like fashion dating around 3 to 2-million years ago . ©Shaen Adey, Gallo Images/Corbis.

The study, led by Matthew Skinner from the University of Kent, compared the internal structures of the hand bones from the Australopithecus africanus and several Pleistocene hominins, which were previously considered to have not engaged in habitual tool use.

Skinner et al, found that they all have a human trabecular (spongy) bone pattern in the metacarpals, and this is consistent with the “forceful opposition of the thumb and fingers typically adopted during tool use”.

Top row: First metacarpals of the various hominins. Bottom row: 3-D renderings from the micro-CT scans showing a cross-section of the bone structure inside.

Figure 2: Top row: First metacarpals of the various hominids.
Bottom row: 3-D renderings from the micro-CT scans showing a cross-section of the bone structure inside. ©T.L. Kivell

The evolution of the hand, mainly the development of opposable thumbs, has been hailed as the key to success for early humans. It is thought that without the improvement of our grip and hand posture, tool technology could not have emerged and developed as well as it has.

This piece of research will provide a new discussion into when the first appearance of habitual tool use occurred in prehistory, as this study’s evidence of modern human-like tool use is dated 0.5-million years earlier than the first archaeological evidence of stone tools.

References:

Skinner, M. Stephens, N. Tsegai, Z. Foote, A. Nguyen, N. Gross, T. Pahr, D. Hublin, J. Kivell, T. 2015. Human-like hand use in Australopithecus africanus. Science. 347, 6220. p395-399.
You can view this paper by clicking here.

 

If you’re a student – check out our ‘Quick Tips’ posts where we breakdown topics of AAFS into bite-sized chunks. We’re currently covering how to age and how to estimate the biological sex of skeletal remains, and also how to identify a variety of fracture types! 

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Quick Tips: How To Estimate The Biological Sex Of A Human Skeleton – Skull Method.

This is the 2nd blog post in this Quick Tips series on estimating the biological sex of human skeletal remains. If you haven’t read the first post on the basics of sexing skeletal remains, click here to start at the beginning.

One of the most widely used methods of sexing skeletal remains is by examining the skull. The skull has five different features that are observed and scored.  The five features are the:

Markers together

Each of these markers is given a numerical score from 1 to 5 relating to the level of expression, with 1 being minimal expression and 5 being maximal expression. Each feature should be scored independently, and without influence from the other identifying features. It has been generally found that female skulls are more likely to have a lower level of expression in all features, whereas male skulls are more likely to have higher levels of expression.

To observe the nuchal crest, one should view the skull from its lateral profile and feel for the smoothness (1-minimal expression) or ruggedness (5-maximal expression) of the occipital surface, and compare it with the scoring system of that feature (Figure 1).

The scoring system for expression levels in the nuchal crest.

Figure 1: The scoring system for expression levels in the nuchal crest.

To observe the mastoid process, one should view the skull from its lateral profile and compare its size and volume, not its length, with other features of the skull such as the zygomatic process of the temporal lobe and external auditory meatus. Visually compare its size with the scoring system of that feature (Figure 2). If the mastoid process only descend or projects only a small distance then it should be scored a 1 (minimal expression), where as if it is several times the width and length of the external auditory meatus, then it should be scored as a 5 (maximal expression).

Figure 2: The scoring system for the size and volume of the mastoid process.

Figure 2: The scoring system for the expression levels of the mastoid process.

To observe the supraorbital margin, one should view the skull at it’s lateral profile and place their finger against the margin of the orbit and hold the edge to determine it’s thickness. If the edge feels ‘extremely sharp’ then it would score a 1, minimal expression, if it felt rounded and thick as a pencil it would score a 5, maximal expression (Figure 3).

Supraorbital Margin

Figure 3: The scoring system for the expression levels of the supraorbital margin.

To observe the supraorbital ridge, one should view the skull from it’s profile and view the prominence of the supraorbital ridge. If the ridge is smooth with little or no projection, then it would score a 1, minimal expression, if it is pronounced and forms a rounded ‘loaf-shaped’ ridge then it would score a 5, maximal expression (Figure 4).

Supraorbital Ridge - Glabella

Figure 4: The scoring system for the expression levels of the supraorbital ridge.

To observe the mental eminence, one should view the skull front facing, and hold the mandible between the thumbs and index fingers, with the thumbs placed either side of the mental eminence. If there is little or no projection of the mental eminence, then it would score a 1, minimal expression, if it is pronounced it would score a 5, maximal expression (Figure 5).

Mental Eminence

Figure 5: The scoring system for the expression levels of the mental eminence.

References:

Buikstra, J.E., Ubelaker, D.H. 1994. Standards for Data Collection From Human Skeletal Remains. Fayetteville, Arkansas: Arkansas Archaeological Survey Report Number 44.

Ubelaker, D.H. 1989. Human Skeletal Remains: Excavation, Analysis, Interpretation (2nd Ed.). Washington, DC: Taraxacum.

White, T.D., Folkens, P.A. 2005. The Human Bone Manual. San Diego, CA: Academic Press. Pg 360-385.

This is the second post of the Quick Tips series on sex determination of skeletal remains. The next post in this series will focus on the use of the pelvis and parturition scars to determine biological sex. To read more Quick Tips in the meantime, click here! 

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Quick Tips: How To Estimate The Chronological Age Of A Human Skeleton – The Basics.

Estimation of age-at-death involves observing morphological features in the skeletal remains, comparing the information with changes recorded for recent populations of known age, and then estimating any sources of variability likely to exist between the prehistoric and the recent population furnishing the documented data. This third step is seldom recognized or discussed in osteological studies, but it represents a significant element. – Ubelaker, D. 1989.

There are numerous markers on a human skeleton which can provide archaeologists and anthropologists with an estimate age of the deceased. The areas of the skeletal remains that are studied are:

If the skeletal marker listed above is a link, it means that I have already covered it in an individual blog post and can be found by following the link.

We can age skeletal remains to a rough estimate, as over a lifetime a human skeleton undergoes sequential chronological changes. Teeth appear and bone epiphyseal form and fuse during childhood and adolescence, with some bone fusing, metamorphose and degeneration carrying on after the age of twenty. Buikstra and Ubelaker, 1994, developed seven age categories that human osteological remains are separated into. The seven age classes are; fetus (before birth), infant (0-3 years), child (3-12 years), adolescent (12-20 years), young adult (20-35 years), middle adult (35-50 years), and old adult (50+ years).

When it comes to ageing skeletal remains, there are numerous problems. This is because individuals of the same chronological age can show difference degrees of development. Therefore, this causes archaeologists and anthropologists to obtain an accurate age estimate, which may not be precise.

It should be noted that it is a lot easier to deduce a juvenile/sub-adult’s age, as the ends of the limb bones form and fuse at known ages and the ages of which tooth formation and eruption occur are very well documented, although somewhat variable. After maturity there is little continuing skeletal change to observe, this causes adult ageing to become more difficult.

References:

Buikstra, J.E., Ubelaker, D.H. 1994. Standards for Data Collection From Human Skeletal Remains. Fayetteville, Arkansas: Arkansas Archaeological Survey Report Number 44.

Ubelaker, D.H. 1989. Human Skeletal Remains: Excavation, Analysis, Interpretation (2nd Ed.). Washington, DC: Taraxacum.

White, T.D., Folkens, P.A. 2005. The Human Bone Manual. San Diego, CA: Academic Press. Pg 360-385.

This is the first of a Quick Tips series on ageing skeletal remains, the next in this series will focus on the epiphyseal closure method of ageing sub-adults. To read more Quick Tips in the mean time, click here! 

To learn about basic fracture types and their characteristics/origins click here!

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Unusual-ology: Unexpected Items in the Bagging Area…

Unusual-ology is a new post type which focuses on weird new articles/science areas that have cropped up and caught my eye.

Archaeologists have made a very peculiar discovery in a churchyard near the St Pancras train station in London. The researchers, led by Phil Emery from Ramboll Cultural Heritage and Archaeology, have stumbled upon a coffin dating back between 1822 and 1858.  What has made the coffin so strange is that it had a large selection of bones from many different animals mixed among human remains. Within the coffin were nine bones from a Pacific walrus (Odobenus rosmarus divergens), eight mixed sets of human remains – including three skulls, and a tortoise.

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Top: Collection of the walrus bones. Bottom Left: The walrus’ back right leg. Bottom Right: The skull showing visible signs consistent with craniotomy.

The coffin was originally discovered in 2003 during excavations of the horizontal burial trench underneath the station, when the Eurostar terminal moved from Waterloo to St Pancras. Emery & Wooldridge (2011) have noted that the bones discovered have marks which are consistent to dissection, which was legalised by the Anatomy Act of 1832, with one skull showing evidence of craniotomy (drilling a hole in the skull to gain access to the brain). As the animal bones were found alongside human remains, Emery believes that the bones were used as a teaching collection from a research institute and has said that:

“The animal bone consisted of a small, moderately-preserved group of eight bones derived from a walrus of a very large size and robust build.’The sample includes bones from a lower fore-limb, a fore-foot, first and second metacarpal, the lower hind limbs, fibula, calcaneum, astragalus and first cuneiform. These bones are significantly larger than their reference equivalents held at the Natural History Museum. Microscopic examination revealed that all the St Pancras walrus bones show some degree of surface erosion and butchery marks. Three clear superficial transverse knife cuts were noted.”

The walrus bones have now been moved to the London Archaeological Archive and Research Centre in Hackney, East London.

If you’ve enjoyed this new ‘Unsual-ology’ post feature – leave a comment or a like!

If you want to read more unusual science posts click here, or to read the Unusual-ology post on the Ancient Egyptian use of lettuce as an aphrodisiac, click here. Or to read about the newly discovered ‘Entrance to Hell’ click here!

 

References:

Daily Mail. 2013. The ongoing mystery around how a Pacific walrus ended up buried in a human coffin beneath London’s St Pancras station. Daily Mail News. Article available here.

Emery, P., Wooldridge, K. 2011. St Pancras burial ground: excavations for St Pancras International, the London terminus of High Speed 1, 2002–3. Gifford, London. This book can be found here. 

Telegraph. 2013. Walrus remains found buried under St Pancras station in London. Telegraph News. Available from here.