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 1minimal expression, if it felt rounded and thick as a pencil it would score a 5maximal 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 1minimal expression, if it is pronounced and forms a rounded ‘loaf-shaped’ ridge then it would score a 5maximal 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 1minimal expression, if it is pronounced it would score a 5maximal 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

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

Within anthropological and archaeological sciences, ‘sex’ refers to the biological sex of an individual, based on the chromosomal difference of XX being female, and XY being male. Whereas ‘gender’ refers to the socio-cultural differences placed on the biological differences. In recent times, the words ‘gender’ and sex’ have been used incorrectly as interchangeable words within this discipline.

Therefore, it is important to remember that the word ‘gender’ refers an aspect of a person’s social identity, whereas ‘sex’ refers to the person’s biological identity.

Sexual dimorphism as seen in the human skeleton is determined by the hormones that are produced by the body. There are numerous markers on a human skeleton which can provide archaeologists and anthropologists with an estimate sex of the deceased. The areas of the skeletal remains that are studied are the:

 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.

The two most commonly used skeletal markers that are observed by osteologists are the skull and pelvic bone, as these show the most extreme differences.

It is generally noted that female skeleton elements are characterized by being smaller in size and lighter in construction, whereas males have larger, robust elements. Due to normal individual variation, there will always be smaller, dainty males and larger, robust females. Therefore, it is always important to observe a variety of skeletal markers to come to an accurate determination.

It should be noted that it is a lot harder to reliably deduce a juvenile/sub-adult’s sex, as many of the differences in skeletal markers only become visible after maturation, when the skeletal changes occur due to puberty. Therefore, use of DNA has been widely used to sex sub-adult skeletal remains as DNA analysis can now detect and identify X and Y chromosome-specific sequences.

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 sex determination of skeletal remains. The next post in this series will focus on the use of the skull to determine biological sex. To read more Quick Tips in the mean time, click here

 

Give-away: Etsy Handmade Archaeology/Anthropology Tool Roll Launch.

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To celebrate the launch of our Etsy shop, which you can visit here https://www.etsy.com/uk/shop/AllThingsAAFS, we are giving away one of our hand-crafted ‘Archaeology Traveller’ small finds/anthropology tool kits (pictured below)!

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 The tool kit includes:

12x Stainless Steel Small Finds Archaeology Tools!
4x Tweezers – to allow you to delicately handle finds!
1x Sharpie permanent marker pen – for labelling tool find trays or bags!
1x Mechanical Pencil – to help you write when the weather is gloomy!
1x HB Pencil – to allow you to sketch your finds, and with extra room to add your own personal tools.
When opened the size of this tool roll is approximately 28x21cm, and will roll up to be 9x21cm.

To be in for a chance of winning this archaeology tool roll, just visit our competition Facebook post by clicking here and then ‘Like and Share’ it! Don’t forget to Like our page to receive updates from us!

Competition ends at 12:00pm on 12th March 2014, and the winner will be selected on the 14th March!

Quick Tips: How To Estimate The Chronological Age Of A Human Skeleton – Pubic Symphyseal Surface Method.

This Quick Tips post is the fifth in the series on age estimation on skeletal remains, if you haven’t read the previous post click here, or to start at the beginning click here. The previous post provides an overview of the cranial suture method of aging, whereas the first post covers the basics.

This method is one of the most common ways of chronically aging a human skeleton, and involves examining the surface of the pubis of the os coxae.

Over a lifetime the surface of the pubis change; in early adulthood the surface is rugged and is traversed by horizontal ridges and intervening grooves. By the age of thirty-five, the surface becomes smoother bound by a rim, as it loses relief. The pubic symphysis of an adult over the age of thirty-five, continues to erode and deteriorate with progressive changes.

These changes were first documented by Todd (1920) who conducted a study on 306 males of known age-at-death. Todd identified that there were four parts to the pubic symphysis, where he noted evidence of billowing, ridging, ossific nodules, and texture:

  1. The ventral border (rampart).
  2. The dorsal border (rampart).
  3. The superior extremity.
  4. The inferior extremity.

Using his observations, Todd identified ten phases of pubic symphysis age, ranging from eight/nine-teen years old to fifty-plus years.

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After Todd’s (1920) method which only looked at males, Suchey-Brooks (1990) undertook a study that involved both female and male pubic symphyses – which allowed for a new symphysis scoring system to be created. This new scoring system is made up of six phases, which have a corresponding statistical analysis for the age that each stage represents. The six stages are as follows:

  1. Lack of delimitation of either superior/inferior extremity; Symphyseal face has a billowing surface (ridges and furrows), which usually extends to include the pubic tubercle. The horizontal ridges are well-marked, and ventral bevelling may be commencing. Although ossific nodules may occur on the either extremity.
  2. Surface has commencing delimitation of lower and/or upper extremities occurring with or without ossific nodules; Symphyseal face may still show ridge development. The ventral rampart may be in beginning phases as an extension of the bony activity at either or both extremities.
  3. Ventral rampart in process of completion; There can be a continuation of fusing ossific nodules forming the upper extremity and along the vetral border. Symphyseal face is smooth or can continue to show distinct ridges. Dorsal plateau is complete. Absence of lipping of symphyseal dorsal margin; no bony ligamentous outgrowths.
  4. Oval outline is complete, but a hiatus can occur in upper ventral rim; Symphyseal face is generally fine grained although remnants of the old ridge and furrow system may still remain. Pubic tubercle is fully separated from the symphyseal face by definition of the upper extremity. The symphyseal face may have a distinct rim. Ventrally, bony ligamentous outgrowths may occur on inferior portion of pubic bone adjacent to symphyseal face. If any lipping occurs, it will be slight and located on the dorsal border.
  5. Symphyseal face is completely rimmed with some slight depression of the face itself, relative to the rim; Moderate lipping is usually found on the dorsal border with more prominent ligamentous outgrowths on the ventral border. There is little or no rim erosion. Breakdown may occur on superior ventral border.
  6. Symphyseal face may show on-going depression as rim erodes; Ventral ligamentous attachments are marked. In many individuals the pubic tubercle appears as a separate bony knob. The face may be pitted or porous, giving an appearance of disfigurement with the on-going process of erratic ossification. Crenulations may occur. The shape of the face is often irregular at this stage.
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Figure 2: The Suchey-Brooks pubic symphasis scoring system of the six stages. It is recommended that these illustrations be supplemented by casts before actual aging is attempted.

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Table 1: Statistics for the Suchey-Brooks phases in females and males.

This pubis symphyseal surface method is often preferred over the other aging methods due to the age-related changes on the pubis surface continuing after full adult stature has occurred, for example; epiphyseal closing method can only age early adulthood.

References:

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

Todd, T.W. 1920 Age changes in the pubic bone: I. The white male pubis. American Journal of Physical Anthropology, 3: 467-470.

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

If you’re new to the realm of archaeological, anthropological and forensic sciences (AAFS), or are a student needing sturdy and reliable references, or wondering “what archaeology or anthropology textbooks to buy? Check out our new ‘Useful Literature’ page!

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Quick Tips: Archaeological Techniques – Ground Penetrating Radar.

Ground-penetrating or probing radar (GPR) is a non-destructive, geophysical method that uses radar pulses to image the subsurface. The principles of ground-penetrating radar are similar to reflection seismology, except that electromagnetic energy is used instead of acoustic energy, and reflections appear at boundaries with different dielectric constants instead of acoustic impedances.

Ground-penetrating radar was applied in the 1940’s after the use of radar to detect enemy aircraft’s during WW2. In 1960’s, due to the progression of this surveying technique, it was primarily used to probe and explore the polar ice. By using GPR in relation to these two applications, a P-38 lightening fighter plane was pinpointed within the ice surrounding Greenland in 1992. The P-38 was originally part of a squadron of six fighters and two B17 Flying Fortresses that ditched just over Greenland in 1942. The P-38 fighter plane was later recovered from a depth of 75m.

How does Ground-penetrating radar work? 

GPR works by emitting high frequency, usually polarized, radio waves via antennas, into the ground. If the area being surveyed contains artefacts or hidden archaeology; these electromagnetic waves are reflected back. When the wave hits a buried object or a boundary with different di-electric constants, the receiving antenna records the variations in the reflected return signal. These returned signals are then collected and interpreted to identify any hidden archaeology within the surveyed area.

N.B. Higher frequencies do not penetrate the ground as far as lower frequencies do, but these higher frequencies give a better resolution. Also the radar emitting antennas are usually in contact with the ground for the strongest signal strength; however, GPR air launched antennas can be used above the ground.

Advantages of Ground-penetrating Radar:

  • GPR is non-destructive and not invasive – helping to preserve the archaeology/landscape.
  • GPR can be used in a variety of media/sediments including; rock, soil, ice, fresh water, pavements and structures.
  • It can detect objects, changes in material, and voids/cracks in the ground.

Disadvantages of Ground-penetrating Radar:

  • The depth range of GPR is limited by the electrical conductivity of the ground. As conductivity increases, the penetration depth decreases. This is because the electromagnetic energy is more quickly dissipated into heat, causing a loss in signal strength at depth.
  • In moist and/or clay-laden soils and soils with high electrical conductivity, penetration is sometimes only a few centimetres.
  • Metal can interfere with the electromagnetic radiation – this can give false results.

References:

Balme, J., Paterson, A. 2006. Archaeology in Practice: A Student Guide to Archaeological Analayses. Oxford, UK: Blackwell Publishing. Pg 218.

Renfrew, C., Bahn, P. 1991. Archaeology: Theories, Methods and Practice. London, UK: Thames & Hudson. Pg 249-53.

Click here to read more Quick Tip posts!

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Quick Tips: Use of Phytoliths in Archaeology.

Phytoliths are a very important identification tool in identifying plants within ancient environments, often even classifying down to the species of the plant.

But firstly, what are phytoliths? As the name phytolith suggests, coming from the Greek phyto- meaning plants and lith– meaning stone, they are tiny (less than 50µm) siliceous particles which plants produce. These phytoliths are commonly found within sediments, and can last hundreds of years as they are made of inorganic substances that do not decay when the other organic parts of the plant decay. Phytoliths can also be extracted from residue left on many different artefacts such as teeth (within the dental calculus), tools (such as rocks, worked lithics, scrapers, flakes, etc.) and pottery.

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Table 1 & 2: Examples of the descriptors found within the International Code for Phytolith Nomenclature (ICPN), 2005, for use of naming phytoliths.
Figure 1: A bulliform phytolith under a microscope, ©Henri-Georges Nation.

Phytoliths can form numerous striking shapes within the plant cells (figure 1), which gives them a characteristic shape, thus aiding the identification of plants. Due to the vast number of shapes and sizes that phytoliths can come in, researchers compiled the International Code for Phytolith Nomenclature (ICPN), 2005. The ICPN was developed to create a standard protocol which is to be used during the process of naming and describing a new or known phytolith type, as well as a glossary of descriptors to help aid with the naming.

To observe phytoliths, a sediment sample needs to be collected preferably away from any human settlements, as the use of agriculture may have introduced non-native plants to the area. The soil sample is then observed under microscope or even scanning electron microscope (SEM). On the discovery of a phytolith after observation it needs to be named using a maximum of three descriptors, the ICPN (2005) can be used to correctly identify what descriptors should be used.

The first descriptor should be of the shape, either using 3D or 2D descriptor (whichever is more indicative/shows the phytoliths symmetry). The orientation of the phytolith should also be noted. The second descriptor should describe the texture and/or ornamentation, if characteristic or diagnostic and not an artefact of weathering.
The third descriptor should be the anatomical origin, but only when this information is clear and beyond doubt (Madella et al, 2005).

Phytoliths are very important and useful if the sediment they are taken from is hostile to the preservation of fossil pollen, so may be the only evidence available for paleoenvironment or vegetation change.

References:

Balme, J., Paterson, A. 2006. Archaeology in Practice: A Student Guide to Archaeological Analayses. Oxford, UK: Blackwell Publishing. Pg 218.

Madella, M., Alexandre, A., Ball, T. 2005. International Code for Phytolith Nomenclature 1.0. Annals of Botany, 96: 253-260. A .pdf of this paper available here.  

Renfrew, C., Bahn, P. 1991. Archaeology: Theories, Methods and Practice. London, UK: Thames & Hudson. Pg 249-53.

Click here to read more Quick Tip posts!

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Quick Tips: How To Estimate The Chronological Age Of A Human Skeleton – Cranial Suture Closure Method.

This is the 4th blog post in this Quick Tips series on chronologically dating human skeletal remains, if you haven’t read the first post click here to start at the beginning. In my previous blog post I introduced the method of chronologically dating sub-adults using dentition, you can find out this information by clicking here.

Another method of chronologically aging human skeletal remains is by observing the cranial suture closure sites. The human skull has seventeen unique cranial fusion sites (Figure 1), that are positioned on the vault, the lateral-anterior sites, and the maxillary suture. The seventeen sites are:

  1. Midlambdoid                                           10.Superior sphenotemporal
  2. Lambda                                                    11. Incisive suture
  3. Obelion                                                    12. Anterior median palatine
  4. Anterior sagittal                                      13. Posterior median palatine
  5. Bregma                                                    14. Transverse palatine
  6. Midcoronal                                              15. Sagittal (endocranial)
  7. Pterion                                                     16. Left lambdoidal (endocranial)
  8. Sphenofrontal                                         17.Left coronal (endocranial)
  9. Inferior sphenotemporal
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Figure 1) Diagram showing the seventeen cranial suture sites.

The first seven fusion sites are on the vault, and the lateral-anterior sites consist of numbers six to ten. Each suture is usually given a numerical score, the score of 0-3 is recommended by the Buikstra and Ubelaker standards (1994). The Buikstra and Ubelaker (1994) scoring system is as follows;

  • 0 is given when the suture is open, meaning there is no evidence of ectocranial closure.
  • 1 is given where there is a minimal closure of the suture.
  • 2 is given to sutures with evidence of significant closure.
  • 3 is given to a completely obliterated suture (complete fusion).

So to attain the age of a skeletal remain you would total the scores for each grouping of sites, vault (1-7) or lateral anterior (6-10), and by comparing the scores to the known composite scores vs. chronological age of Meindl And Lovejoy, 1985 (Figure 2).

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Figure 2: Table demonstrating Meindl and Lovejoy (1985)’s composite scores of the sutures on the vault and lateral-anterior, respectively, in relation to mean chronological age.

A very useful cranial suture site is the sphenooccipital synchrondrosis, because at least 95% of all individuals have fusion here between the ages of twenty and twenty-five, with most individuals experiencing complete fusion around the age of twenty-three (Krogman and Işcan, 1986).

References:

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

Krogman, W.M., Işcan, M.Y. 1986. The Human Skeleton in Forensic Medicine (2nd Ed). Springfield, Illinois: C.C. Thomas.

Meindl, R.S., Lovejoy, C.O. 1985. Ectocranial Suture Closure: A Revised Method For The Determination Of Skeletal Age At Death Based On The Lateral-Anterior Sutures. American Journal of Physical Anthropology. 68, 57-66.

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

This is the forth of a Quick Tips series on ageing skeletal remains, the next in this series will focus on the use of the pubic symphyseal surface to chronologically age skeletal remains. To read more Quick Tips in the meantime, click here

To learn about basic fracture types and their characteristics/origins in their own Quick Tips series, click here!

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Quick Tips: How To Estimate The Chronological Age Of A Human Skeleton – Using Dentition To Age Subadults.

This Quick Tips post is the third in the series on age estimation of human skeletal remains, if you haven’t read the first post click here to start at the beginning. The first post provides an overview of the different techniques utilised by archaeologists/anthropologists, which will each be covered in more detail in their own blog post, and the categories that human skeletal remains are placed under according to their chronological age. The second post examines the epiphyseal closure method, which you can find here.

The practice of using dentition to chronologically age human skeletal remains is split into two halves, depending on the whether the skeleton is that of a subadult or adult. This blog post is going to discuss using dentition to age subadults.

Due to the abundance of teeth found in many archaeological, forensic, paleontological, and anthropological contexts and because of the regular tooth formation and eruption times, dental development is the most widely used technique for aging subadult remains. As stated in my previous blog post, several elements of the human skeleton begin the stages of epiphyseal fusion alongside the conclusion of tooth eruption; these two techniques (dentition and epiphyseal closure) are often used complementary to each other to help age sub-adults. When it comes to subadult tooth emergence there are four stages:

Stage 1 is where most of the deciduous teeth, commonly referred to as ‘milk teeth’, emerge during the second year of life.

Stage 2, during this stage the two permanent incisors and the first permanent molar emerge, this stage typically occurs between the age of six and eight years.

Stage 3, occurs between the age of ten and twelve and it involves the emergence of the permanent canines, premolars, and second molars.

Stage 4, or the final stage involves the third molar emerging around the age of eighteen years.

When looking at dentition you must look at all aspects of emergence and not just at the fully erupted tooth, which includes the completeness of all roots and crowns (formation) and the position of each tooth relative to the alveolar margin (eruption). Ubelaker (1989) conducted a study on non-Native Americans and created a graphic summary of dental development and the correlating ages it occurs, see figure 1.

Figure 1: Ubelaker's (1989) diagram showing the dental development in correlation to age.

Figure 1: Ubelaker’s (1989) diagram showing the dental development in correlation to age.

It must be noted that the ages these stages occur at differ per individual so only act as a reference. Gustafson and Koch (1974) created a graph to illustrate the variation that could occur with dental development, see figure 2.

Figure 2: Gustafson and Koch's (1974) image showing the variation in timing of dental development. Colour key: Black highlights the age that crown mineralization begins, Dark grey shows the age of crown completion, Light grey shows the age of eruption, and White displays age of root completion.

Figure 2: Gustafson and Koch’s (1974) image showing the variation in timing of dental development. Colour key: Black highlights the age that crown mineralization begins, Dark grey shows the age of crown completion, Light grey shows the age of eruption, and White displays age of root completion.

References:

Gustafson, G. Koch, G. 1974. Age estimation up to 16 years of age based on dental development. Odontologisk Revy. 25. Pg 297-306.

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 third of a Quick Tips series on ageing skeletal remains, the next in this series will focus on the use of dentition to age adults and the use of cranial suture closure. To read more Quick Tips in the meantime, click here

To learn about basic fracture types and their characteristics/origins in their own Quick Tips series, click here!

 

Quick Tips: Named Fractures – Part One: Hand & Forearms

This blog post is the 3rd in its series on bone fractures. To view the first blog post on the basic fracture types and information, including open and closed fractures, click here.

This blog post will highlight some of the common ‘named’ fractures you will often find in archaeological and anthropological settings. It is important to know their characteristics and common causes to help establish what happened – whether the fracture was received by defensive or offensive action, or purely accidental. This blog post will examine the first five common fractures associated with the hand and forearm bones.

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Common ‘Named’ Fractures of the forearms and hands: A) Boxer’s fracture, B) Bennett’s fractures, C) Parry’s or Monteggia’s fracture, D) Colles’ fractures, and E) Smith’s fractures.

The first two fractures we will look at affect the metacarpal bones;

A)     Boxer’s fracture: This fracture occurs due to the axial loading, meaning a force was applied along/parallel to the axis of the bone, on the transverse neck of the 4th and 5th metacarpal, secondary to an indirect force. A Boxer’s fracture often happens due to punching an object/person with a closed fist, hence the name ‘Boxer’ being associated to it.

B)      Bennett’s fracture: This fracture affects the 1st metacarpal (thumb) and extends into the carpometacarpal (CMC) joint which is complicated by subluxation (dislocation of a joint). A Bennett’s fracture is an oblique (See 1st blog post for meaning, click here) intra-articular metacarpal fracture caused by an axial force directed against the partially flexed metacarpal. This injury is also common when someone punches a hard object, but its most common cause is falling onto the thumb. An example of this is falling off a bike, as the thumb is extended around the handle bars.

The last three fractures affect the longbones of the forearm, the ulna and radius;

C)      Parry’s/Monteggia’s fracture: This fracture occurs on the proximal third of the ulna with subluxation of the radius/ulna. The most common cause of this fracture is by blunt force trauma caused by lifting the forearm up to protect the head or body in defence from an oncoming attack/striking object.

These two fractures affect the distal radius but cause displacement in two directions;

D)     Colles’ fracture: A Colles’ fracture, also known as a “dinner fork” or “bayonet” fracture, occurs when the distal radius is broken with dorsal displacement of the wrist and hand. This fracture is common when the person falls forwards and uses their outstretched hand to cushion the fall, which causes the force to displace and break the head of the radius.

E)      Smith’s fracture: A Smith’s fracture is the same as the Colles’ fracture but with ventral displacement of the broken radius head. The cause of a Smith’s fracture is the same as the Colles’ fracture, but it is less common.

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Fractures: D) Colles’ fracture, and E) Smith’s fracture.

The next Quick Tips post will discuss other ‘named fractures’ in archaeological/anthropological situations and their causes and characteristics.

This is the third post of a set on fractures, so keep your eyes open for the other posts, and the new ones to come. To view all the other Quick Tips posts click here!

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Quick Tips: Forensic Entomology – An Introduction.

What is forensic entomology? It is a discipline within forensic sciences where specialists use information that they know about insect lifecycles and behaviours to interpret evidence in a legal context, relating to humans and animals. Entomologists don’t just stick to insects; their work can expand to include other arthropods, mites, spiders and macro-invertebrates.

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Insect species which are relevant to forensic entomology

What information can we learn from insect activity? Insects are everywhere and can hardly be avoided, so it’s no surprise that sometimes they get mixed up in the evidence left behind – making them extremely valuable to an investigation. Insects can be a vital part of forensic science as they can provide a time and date to a crime or even a geographical position to where it happened. As some insects only become apparent during certain months, they can become a biological calendar for when a crime might have been committed. As well as being a biological calendar, certain insect species are only native in specific countries or hemispheres. This can be used to create an ‘X marks the spot’ on where a crime was committed – even if a body was moved/buried. Because of this, insects can be the key to past and present events as well as the future.

The insects that are particularly relevant to forensic entomological investigations are blow flies (diptera), flesh flies, cheese skippers, hide and skin beetles, rove beetles and clown beetles. These forensically relevant insects can be placed in four categories:

  • Necrophages, which feed only on the decomposing tissue of the body or body parts. This is the category that blow flies, hide beetles and clown beetles are classed under.
  • Predators of the necrophages – for example the rove beetles and ground beetles.
  • Omnivores that consume both the live insects inhabiting the corpse and the dead flesh – ants and wasps.
  • Opportunist species, which arrive because the corpse is a part of their local environment. This is where mites, hoverflies, butterflies and occasionally spiders are classified.

Forensic entomologists use the evidence they gain from studying insects within legal cases in either civil or criminal courts. Civil court cases include:

  • Insect infestation in urban contexts.
  • Stored product infestations/pests.

Criminal court cases include:

  • Neglect – either animal or human (elderly and children).
  • Insect infestation of a body – living or dead.
  • Death in which foul play is suspected.

This is just an introduction into the world of forensic entomology, if you’d like to know more or further your knowledge on this topic check out this book, I found it very interesting and a terrific read:

  • Forensic Entomology: An Introduction (UK/Europe)
    Forensic Entomology: An Introduction (US/Worldwide Link)
    by Dorothy Gennard. Rating – ***
    “I used my this for my blog post on the basics of forensic entomology. It is perfect if you’re unsure on whether or not you want to pursue this career/discipline. Definitely a good read if your interest is sparked by Dr Hodgins from ‘Bones’, as it explained everything involved within entomology under legal settings.”