Quick Tips: How to Estimate the Biological Sex of a Human Skeleton – Pelvic Dimorphism.

This is the 3rd 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 or if you skipped the 2nd post focusing on the skull method if sex estimation, click here.

When it comes to sexing skeletal remains by the pelvic elements there are a few trends, as stated in the first blog post in this series, the female pelvic bones, specifically the sacra and ossa coxa are smaller and less robust than their male counterparts.

Figure 1: Side by side size comparison of a male (left) and female (right) pelvis.

Figure 1: Side by side size comparison of a male (left) and female (right) pelvis.

Although the female pelvic components are smaller in general, many aspects of the female pelvis are wider than males. The pelvic inlets on a female are relatively wider than those of males, as well as the greater sciatic notches – which is thought to aid childbirth.

Figure 2: Basic annotated diagram of the pelvis.

Figure 2: Basic labelled diagram of the pelvic anatomy.

There are numerous features of the pelvic bones that are examined to identify the biological sex of an individual, alongside the trends stated about. These features are as follows;

  • The ventral arc.
  • The subpubic concavity.
  • The medial aspect of the ischiopubic ramus.
  • The greater sciatic notch.

The first three features listed above, are known as the Phenice method – which was proposed by T. W. Phenice in 1969. His paper, “A Newly Developed Visual Method of Sexing the Os Pubis”, contributed greatly to the method of visual determination of sex, as beforehand the methods were subjective and based largely on the osteologist’s experience. The Phenice method should only be used for fully adult skeletal remains, where it is 96 to 100% accurate.

The ventral arc is a slightly raised ridge of bone that sweeps inferiorly and laterally across the central surface of the pubis. It joins with the medial border of the ischiopubic ramus. The ventral arc is only present in females, although males may have raised ridges in this area, but these do not take the wide, evenly arching appearance of the ventral arc.

Figure 2: The ventral arc is characterised by a slightly raised ridge of bone. Males do not exhibit the ventral arc, where as females do.

Figure 3: The ventral arc is characterised by a slightly raised ridge of bone. Males (left) do not exhibit the ventral arc, where as females (right) do.

To observe the subpubic concavity, you should turn the pubis so that the convex dorsal surface if facing you. Then you should view the medial edge of the ischiopubic ramus. Females display a subpubic concavity here where the edge of the ramus is concaved, whereas males tend to have straight edges or very slightly concaved.

Figure 4: Females display a subpubic concavity here where the edge of the ramus is concaved, whereas males tend to have straight edges or very slightly concaved.

Figure 4: Females (right) display a subpubic concavity here where the edge of the ramus is concaved, whereas males (left) tend to have straight edges or very slightly concaved.

To observe the medial aspect of the ischiopubic ramus, you should turn the pubis 90° so that the symphyseal surface is directly facing you. View the part of the ramus that is directly inferior to the pubis symphysis. In females, the ramus has a sharp, narrow edge, whereas in males it is flat and blunt.

Figure 5: In females (right), the medial aspect of the ischiopubic ramus has a sharp, narrow edge, whereas in males (left) it is flat and blunt.

Figure 5: In females (right), the medial aspect of the ischiopubic ramus has a sharp, narrow edge, whereas in males (left) it is flat and blunt.

As with the five features of the skull used to sex a skeleton in the previous, the greater sciatic notch has also been given a numerical score from 1 to 5 relating to the level of expression. It has been generally found that female os coxae are more likely to exhibit a lower level of expression, whereas male os coxae are more likely to have higher levels of expression.

Figure 6:

Figure 6: It has been generally found that female os coxae are more likely to exhibit a lower level of expression, whereas male os coxae are more likely to have higher levels of expression, when it comes to the greater sciatic notch.

To obtain the best results whist examining the os coxae, it should be held in the same orientation as the pictured above. This allows you to match the angle of the greater sciatic to the closest expression that represents it. It should be noted that this method is usually used as a secondary indicator.

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 392-398.

This is the third post of the Quick Tips series on sex determination of skeletal remains. The next post in this series will focus on the use of DNA to determine biological sex. To read more Quick Tips in the meantime, click here

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Quick Tips – Common Questions: What can an anthropologist tell from the examination of teeth regarding either forensic identification of individuals or understanding past populations?

This is a Quick Tips post providing a basic answer to a commonly asked question often faced within the field of archaeology and anthropology.

An anthropologist can obtain a wide and varied collection of information from examining teeth. Information such as paleodiets and palaeoenvironments can be learnt from studying a population, or from studying an individual sample you can identify how old the person was at time of death or whether that person was pregnant/ill. These examples are just the tip of the iceberg on what you can learn from dentition.

Ondontology

An anthropologist can obtain a wide and varied collection of information from examining teeth, ranging from palaeodiets and palaeoenvironmental information to age of death.

From studying a large population dentition sample, a picture can be painted of their past diets, current diets and palaeoenvironments. Isotopes play a huge part in conducting research into palaeodiets and palaeoenvironments.

Isotopes are deposited into the teeth of an individual/population from food sources or environment. A tooth can provide isotopic information from the past 20yrs of the individual’s life. The enamel and dentine can be examined to analyse the isotopic values that will pinpoint an origin of a population or food sources. The carbon and nitrogen isotope compositions found within the enamel are used to reconstruct diet and the oxygen isotopes are used to determine the geographic origin of the food source. The carbon isotopes are absorbed from the diet of the animals that are sources and the oxygen isotopes from the water that the population consume. These isotopic values are vital in helping an anthropologist understand the local ecosystem a population exploited and whether a population migrated to numerous locations which caused changes in the available diet.

The cementum of a tooth can highlight important information about a person which can be used for forensic identification; this information could give an approximate age of death. An example of this application is seen in Kagerer and Grupe (2000) study where they obtained 80 freshly extracted teeth and investigated the incremental lines in acellular extrinsic fibre cementum. From studying the cementum, they were able to determine the age of the patient by comparing it to detailed queries of the patients life history. This study also identified patients who were pregnant. Kagerer and Grupe (2000) concluded that if there was a presence of hypo-mineralised incremental lines on the extracted tooth, the patient was pregnant. This is due to the pregnancies influence on calcium metabolism. A confliction with this is that hypo-mineralized lines can also appear when a skeletal trauma or renal illness was present.

By looking at the dentition of molars the age of the skeleton can be estimated. A recent study by Mesotten, et al. (2002) highlighted the application of forensic odontology. Mesotten, et al’s methodology consisted of examining 1175 orthopantomograms which belonged to patients who were of Caucasian origin and were aged between 16 and 22years. From their investigation Mesotten, et al. were able to conclude that from studying the molars, it was possible to age Caucasian individuals with a regression formula with a standard deviation of 1.52 or 1.56 years for males and females, respectively, if all four third molars were available. This could play a fundamental role in identifying a missing person by estimating the decease’s age and seeing if its estimate matches the individual.

Although the studies from Mesotten, et al (2002) and Kagerer and Grupe (2000) have been written about and applied to individual cases, their methodology and conclusions can be applied to a past population if a group of skeletons were found with preserved teeth. The individual’s age of death can be used as quantitative data, alongside other individuals from the same sample, to figure out a past population’s life expectancy.

References:

Kagerer, P. Grupe, G. 2000. Age-at-death diagnosis and determination of life-history parameters by incremental lines in human dental cementum as an identification aid. Forensic Science International. 118, 1. 75-82.

Mesotten, K. Gunst, K. Carbonez, A. Willems, G. 2002. Dental age estimation and third molars: a preliminary study. Forensic Science International. Volume 129, Issue 2, 110-115

To learn how archaeologists and anthropologists use teeth to age skeletal remains, read our Quick Tips: How To Estimate The Chronological Age of a Human Skeleton – Using Dentition to Age Subadults. Or to read more of our interesting Quick Tips, click here.

Quick Tips – Common Questions: Can physical activities undertaken during life be detected on skeletal remains?

This is a Quick Tips post providing a basic answer to a commonly asked question often faced within the field of archaeology and anthropology.

Can physical activities undertaken during life be detected on skeletal remains? Yes they can.

Numerous activities, such as hunting, gathering, exercise and more obviously fighting, can inflict damage or adaptations onto to a skeletal system. Some physical activities can be easily identified by due to the damage they can produce to the skeleton, i.e. fighting, whereas the skeletons adapt to strain caused by sport or a daily activity can be harder to detect.

Stock (2006) investigated hunter-gatherer postcranial robusticity relative to patterns of mobility and climatic adaption. In this study, Stock took four collections of known hunter-gatherers skeletal remains along with the associated data of the environmental factors in the population area and the terrestrial mobility. In every analysis conducted, the effective environmental temperature was found to be negatively correlated with strength. Stock concluded that hunter-gatherers from colder climates tend to have stronger long bone diaphysis, than the groups from warmer regions. Although in contrast, the partial correlations between mobility and robusticity are positive; suggesting that activity has a consistently positive relationship with diaphyseal strength. This study indicates that even the simple ‘easy’ activity of hunting and gathering can affect diaphyseal strength of a skeleton and that the activity can be detected.

Exercise is also one of the most common factors to cause a skeleton to adapt. A recent study by Shaw (2009) was able to correctly predict an athlete’s chosen sport from quantifying the soft tissue properties and bone morphology. In Shaw’s study he focused on examining modern athletes (runners, field hockey players, swimmers, and cricketers) and a control group. Using peripheral quantitative computed tomography (pQCT), Shaw quantified the relationship between the amount of muscle and other soft tissues and the morphology of the bones along the midshaft of the arm, forearm and lower legs. This study concluded that Shaw could correctly identify an athlete’s chosen sport from examining a skeletal system and quantifying the bone mass and strength. Shaw concluded that the changes to the bones structural properties were from the strain of daily habitual training from the athlete’s young age.

These two modern studies, Stock (2006) and Shaw (2009), perfectly highlight how physical activities can be detected on skeletal remains.  But these morphological changes can be harder to detect than more brutal activities such as fighting. This is because war and fights leave tell-tale marks on the skeletons which are detectable from eye rather than quantitating data. Violence within a population whether its ritual/habitual, in times of war or domestic can be easily identified from the fractures and dents a bone receives.

A recent NAI (Non-accidental Injury) study from Day et al (2006), highlighted how skeletal remains could indicate bone trauma caused by violence. The study retrospectively observed cases of suspected NAI injuries sustained by children from X-rays obtained at an Edinburgh hospital. The bone fractures, mostly found on the skull and long bones, were suspected to be cause by domestic abuse and evidence of blunt force trauma was observed in numerous cases. Even though this is a recent study conducted on NAI instances, it does appropriately show how violence can inflict damage onto skeletal remains. An archaeological skeleton could show healed/unhealed fractures sustained via a physically demanding activity which was violent in nature, such as war or ritual fighting.

References:

Day, F. Clegg, S. McPhillips, M. Mok, J. 2006. A retrospective case series of skeletal surveys in children with suspected non-accidental injury. Journal of Clinical Forensic Medicine. 13, 12. 55-59.

Shaw, C. 2009. ‘Putting flesh back onto the bones?’ Can we predict soft tissue properties from skeletal and fossil remains?. Journal of Human Evolution. 59, 5. 484-492.

Stock, J.T. 2006. Hunter-Gatherer Postcranial Robusticity Relative to Patterns of Mobility, Climatic Adaption and Selective Tissue Economy. American Journal of Physical Anthropology. 131, 2. 194-203.

 

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.

Etsy Header2

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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