21/08/2013 by All Things AAFS!

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

This Quick Tips post is the second in the series on age estimation on skeletal remains, if you haven’t read the previous post click here. The previous 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.

One of the methods frequently used by archaeologists/anthropologists to estimate the chronological age of human remains is by studying the level of epiphyseal fusions.

But first what is an epiphysis? An epiphysis is the cap at the end of a long bone that develops from a secondary ossification center. Over the course of adolescence the epiphysis, which is originally separate, will fuse to the diaphysis. The ages of which epiphyseal fusion begins and ends are very well documented, with the majority of epiphyseal activity taking place between the ages of fifteen and twenty-three.

Diagram showing where the epiphysis is found.

As epiphyseal fusions are progressive they are often scored as either being unfused (non-union), united, and fully fused (complete union). Females often experience the union of many osteological elements before males, and every individual experience epiphyseal union at different ages.

Left: Diagram of a skeleton showing the position of the different epiphyseal elements.
Right: A graph displaying the timing of fusion of epiphyses for various for various human osteological elements. The grey horizontal bars depict the period of time, in ages, when the fusion is occurring. All of the data is representative of males, except where it is noted. Data taken from Buikstra & Ubelaker, 1994.

Archaeologists/anthropologists use standards that are well known and documented, such as Buikstra & Ubelaker’s (1994) depicted in the above graph. From the above data we know that, for example, the fusion of the femur head to the lesser trochanter is begins around the age of fifteen and a half and ends around the age of twenty. So if a skeleton has evidence of an unfused femur head/lesser trochanter, there is a possibility of the skeleton having a chronological age of < fifteen years. If there is full union of the epiphyses then the skeleton is more than likely being > twenty years old. But it should be noted that individuals vary in their development so numerous elements should be examined before coming to an accurate conclusion.

Different stages of epiphysis fusion of human tibias. Ages left to right: Newborn, 1.6 years old, six years old, ten years old, twelve years old and eighteen years old.

As 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. The next post in this series on age estimation will focus on the use of dentition to aid with the chronological ageing of human remains.

References:

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

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

This is the second of a Quick Tips series on ageing skeletal remains, the next in this series will focus on the dentition 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!

20/08/2013 by All Things AAFS!

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:

Cranial suture closure.
Dentition.
Epiphyseal closures.
Ilium auricular surface.
Long bone length.
Pubic symphysis.
Sternal rib end.
Radiographical analysis.
Bone microstructure.

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!

09/08/2013 by All Things AAFS!

Quick Tips: Fracture Types – The Basics Pt 2.

In my previous Quick Tips, which you can find by clicking here, you were introduced to the first six basic types of fractures, what the main causes of fractures are, and the two main categories they are classed in. It is important that you know the information in the previous Quick Tips post before learning these last few basic fractures, as it discussed the fundamentals of fractures.

Basic Fracture Types:

Fracture Types: A) Butterfly, B) Longitudinal, C) Segmented, D) Hairline, and E) Avulsion.

A) Butterfly Fracture: Butterfly fractures usually affect long bones and can be caused by car accidents or by being knocked side on.

B) Longitudinal Fracture: As a transverse fracture is a bone along the horizontal axis, a longitudinal fracture is along the vertical axis.

C) Segmented Fracture: This is when the bone has fractures in two parts of the same bone causing the bone to break into larger bone fragments which are separated from the main body of a fractured bone.

D) Hairline Fracture: These fractures are also known as ‘stress fractures’. These types of fractures are very difficult to diagnose and once they heal there may be no evidence left to see. These are very difficult, if not impossible to identify when in an archaeological context.

E) Avulsion Fracture: Avulsion fractures are characterised as the separation of a small fragment of bone at the site of attachment of a ligament or tendon.

The next Quick Tips post will discuss the ‘named fractures’ that can be discovered in archaeological contexts, such as the familiar Bennett’s and Parry’s fracture, and their origins and common causes.

This post was put together by using knowledge from my degree and supplemented with the textbook ‘The Archaeology of Disease’ by Charlotte Roberts & Keith Manchester. If you’re interested in the latest scientific and archaeological techniques used to understand the diseases of past populations, you should check it out!

This is the second post of a set on fractures, so keep your eyes open for the other posts. To view other Quick Tips posts click here!

07/08/2013 by All Things AAFS!

Quick Tips: Fracture Types – The Basics.

In my previous Quick Tips post I addressed how to distinguish between ante, peri and post-mortem fractures, click here if you haven’t read it yet.

In this Quick Tips post I will show you some ways to identify and deduce common fracture types and their key characteristics. The definition of a fracture is a break in the continuity of a bone. There are three major causes of fractures: acute injury (an accident); underlying disease which then weakens the bone making it susceptible to fractures; and repeated stress (as seen in athletes).

All fracture types can be placed in two categories; open and closed. An open fracture, also known as a compound fracture, is where the bone breaks through the skin causing an open wound. It is called an open fracture as there is an open connection between the fracture site and skin. A closed fracture is where the bone has no connection between the outer skin surface and the fractured bone itself; it does not cause an open wound. A closed fracture is classed as a ‘simple fracture’.

Basic Fracture Types:

Fracture Types: A) Transverse, B) Oblique, C) Spiral, D) Comminuted, E) Greenstick, and F) Impacted fracture.

A) Transverse Fracture: This is when the break of a fracture is in a horizontal line, it is the simplest fracture type.

B) Oblique Fracture: This fracture is a break which extends in a slanting direction. Oblique fractures are caused by indirect or rotational force.

C) Spiral Fracture: As you can guess from the name, this is a fracture which is characterised by a spiral. It is often denoted as being caused by torsion or force onto the bone.

D) Comminuted Fracture: A comminuted fracture is characterised from the splintering of the bone. This causes the fracture to be made up of two or more pieces. This fracture is common in road-traffic accidents and these fractures are less likely to heal in a functionally satisfactory manner.

E) Greenstick Fracture: This occurs when a transverse fracture is incomplete. This fracture is seen mainly in children due to their young, immature bones which rarely break the whole width.

F) Impacted Fracture: This occurs when the bone is broken and not displaced but the two fractured ends are forced together. This produces a rather stable fracture which can heal readily but there may be some length lost.

This is the first post of a set, click here to read the second post. To view other Quick Tips posts click here!

27/07/2013 by All Things AAFS!

Quick Tips: How can you tell if a skeletal fracture is ante, peri or post-mortem?

There is a relatively easy way to see whether a fracture to a skeleton is ante, peri or even post mortem. It is essential to detail and deduce which category a fracture falls into, as this is very important to see whether the fracture had played a part in the person’s death.

To first classify a fracture, we need to understand what the different categories mean. Some of you will already know these terminology, but here’s a quick reminder;

If a fracture is ante-mortem, it means that the fracture was made before death of the persons.
With peri-mortem fractures, it means that the fracture was received at or near the time of death of the persons – so could have been the fatal strike.
Post-mortem fractures are fractures that have been received after death, so during the time from death to the time of recovery. These fractures are usually from excavation processes, dismemberment, or even natural processes (soil, animal and plant activity).

You will be able to determine if a bone fracture was ante-mortem due to there being signs of healing which is shown by cell regrowth and repair.

With peri-mortem fractures, the person died before the healing started to take place, but the fractures will still contain the biomechanics that are present in ante-mortem fractures.

Post-mortem breaks tend to shatter compared to peri-mortem breaks which splinter, this is because bones which are in the post-mortem stage tend to be dry and rather brittle. Another big indicator of a fracture being post-mortem is the difference in colour.

The ‘Quick Tip’ that my applied anthropology lecturer taught me on how to easily distinguish between peri-mortem and post-mortem is to look at the fracture and decide; is it a clean break, as if you were breaking in half a bar of chocolate? If it is, then the fracture is most likely to be a peri-mortem fracture. If the break looks crumbly, like breaking a biscuit in half, it’s post-mortem fracture. Obviously this tip is not the most scientific, but it’s an easy way to begin your distinguishing process.

Skull with signs of post-mortem fractures. This photo is from a practical lab session.

If you look at the photo above it illustrates a post-mortem fracture. You can determine this easily due to the colour difference on the edge of the fracture, where it is a much lighter colour compared to the rest of the skull and the crumbly nature of the cut.

References:

Most of this is my own knowledge that I learnt during my degree in my anthropology lectures/lab practical sessions. But if you’re looking for a published journal check the one below. It is very informative and easy to understand if you’re a beginner in the world of anthropology/archaeology! It also highlights some problems that can arise when distinguishing trauma, it’s really interesting!

Smith, A.C. 2010. Distinguishing Between Antemortem, Perimortem, and Postmortem Trauma. Academia.edu. Available from here in .pdf form!

19/07/2013 by All Things AAFS!

Quick Tips: The Use of 3D Animation to Visualise a Crime Scene in Forensics.

Many television programs create 3D animations and computer generated images using highly technical computer programmes to help re-enact the scenes or time frame of a crime. This is mostly used so that the viewer at home can really grasp what crime has been committed and help establish a sense that they are a witness. But in reality these animations and images are becoming an increasingly popular technique used within the courtroom.

Information and evidence can be easily constructed from the traditional methods of forensic photography, blood spatter analysis and eye witness testimonies. But in this modern technological time the information gathered is now being used to create computerised animation that depicts the series of events within a crime. But is this method of providing visual appropriate and correct? Could the animation be showing a display of actions/movements that humans can’t possibly and physically make?

There is a big issue with admissibility, which can cause bias. This occurs when the jurors or judge aren’t aware of an error/uncertainty within the procedure of recreating a real life scene into animation. This can cause them to believe that the evidence is a hundred per cent correct, when in fact there are many errors which were created in the process or animation (Ma & Zheng, 2010). Another big problem arises when studies found that people are five times more likely to remember something they see and hear rather than hearing alone. People are also twice as likely to be persuaded if the arguments are backed with visual evidence (Lederer & Solomon, 1997). So this poses a huge problem as false memories and false testimonies could be influenced, which in the end could cause an innocent person to go to jail for a crime they did not commit.

So with the possibility of creating false memories is the use of 3D animation beneficial for the use of visualising crime scenes within court? It is argued that it is as the use of computerised images creates a higher level of accuracy and speeds up the forensic investigational process but only in major crime types, not every day homicides and robberies. However even though it has limited application in the courtrooms, it can pose to be very useful in formal briefs with the forensic personnel, and within the backstage elements of the investigation itself (Ma & Zheng, 2010).

References:

Lederer FI, Solomon SH. 1997. Courtroom technology – an introduction to the onrushing future. Fifth National Court Technology Conference: National Centre for State Courts. Available here.

Ma M, Zheng H. 2010. Virtual Reality and 3D Animation in Forensic Visualization. Journal of Forensic Sciences. 55, 5. 1227-1231.