Quick Tips: How To Estimate The Chronological Age Of A Human Skeleton – Sternal Rib End Method.

This Quick Tips post is the sixth 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 pubic symphyseal surface method of ageing, whereas the first post covers the basics.

The method was primarily developed by Iscan and Loth (1986) who studied the metamorphosis of the sternal end of the fourth rib. They found that the metamorphosis corresponds to the age but does vary by sex.

In their study they examined the “form, shape, texture and overall quality” of the sternal end which is found at the anterior (ventral) end of the shaft. This end is a roughened, porous, cupped oval surface which attaches to the cartilage attached to the sternum.  From this they were able to define a series of phases that depict the metamorphism of the sternal rib end over time.

Rib anatomy

Anatomy of the rib cage. This method was primarily developed by Iscan and Loth (1986) who studied the metamorphosis of the sternal end of the fourth rib. They found that the metamorphosis corresponds to the age but does vary by sex.

At the start the sternal end is flat or billowy with regular and rounded edges, and over time its rim thins and become irregular, with the surface porosity increasing, and the end becomes irregular. This method can be applied cautiously to the 3rd or 5th ribs as well, but not the others.

References:

Iscan, M.Y., and Loth, S.R. 1986. Estimation of age and determination of sex from the sternal rib. In: K. J. Reichs (ed.) Forensic Osteology: Advances in the Identification of Human Remains. Springfield, Illinois. Pg 68-89.

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: 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: 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.

Epiphyses

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.

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.

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!