Human bone analysis is a vital part of archaeology. Analysing the appearance and chemical composition of bones reveals a wealth of information about the lives and lifestyles of people from the past. 

The Value of Human Bone Analysis

Human bone analysis can provide a wealth of information. It can reveal information about sex, age and appearance and provide information about life expectancy, mortality, social and economic conditions and the standard of living of individuals and communities over time. Human bones can even be used to establish where an individual grew up. 

So how do human bones reveal this information?

Age

Age can be determined from human bones in various ways: 

·      Bone fusion. Bones pass through various stages before becoming fully fused in adulthood at around 30, so the stage of an individual’s bone fusion at the time of death can determine their age. 

The collar bone is one of the last bones to fuse, with the base of the spine or the sacrum fusing between 16 and 23. Full skull fusion is usually only complete in full-grown adults. However, skulls can still help gauge approximate ages in adolescents by looking at the thickness of the bone, which increases with maturity.

·      Teeth. The stage of tooth eruption is a good indicator of an individual’s age at the time of death, as is the development of ridges in the tooth enamel. Teeth in the past often became worn down and heavily eroded due to the high proportion of grit in the milled flour, so the more eroded the teeth, the older the individual. However, tooth erosion can only provide a rough guide to age.

·      Bone microstructure: Young bones have rings about their circumference. These disappear as the individual ages.

·      Levels of citrate: This chemical is found in high proportions in female bones between puberty and menopause.

·      Wear and tear. As with teeth, once bones are fully developed, age can be estimated from wear and tear. For instance, the pelvic bones and the ends of certain ribs deteriorate over time, allowing an estimate of the individual’s age. However, this estimate is imprecise at best, only allowing experts to place the individual within broad categories (“young adults” — 20-35, “middle-aged” — 35-50 or “old” — 50 and above).

Sex

While it can be difficult to sex juvenile bones, in adults, the following can indicate whether remains are male or female:

·      Bone size. Male bones are generally longer and larger than female and have more obvious muscle markings.

·      The skull. Males have bigger skulls with more prominent brow ridges and mastoid processes (bumps behind the ear.) They also tend to have more prominent jaws.

·      The pelvis. The male and female pelvis is very different, making it one of the best indicators of sex. Generally, the pelvic cradle is wider in females than in males. However, size isn’t all that matters when looking at this part of the skeleton. The subpubic concavity will be narrower or absent altogether in the male pelvis, while a female pelvis will have a broader sciatic notch and a sharp ridge on the ischiopubic ramus (this is flat on the male pelvis). Other areas unique to the female pelvis include the preauricular sulcus (only occasionally a feature of the male pelvis) and a ventral arch.

·      Citrate level. Adult female bones show higher levels of this chemical than male bones because of the female hormone cycle.

Diet and Lifestyle

The presence of certain isotopes and various visual indicators on bones can provide important information about an individual’s diet and lifestyle that can help build up pictures of the lifestyles of whole communities and any variances between classes and groups:

·      Analysis of different isotopes or trace elements in the bones and teeth, such as strontium, can indicate the basis of an individual’s diet — i.e. whether it was predominantly vegetarian, maritime or meat-based. Isotope analysis also allows experts to differentiate between cereal and non-cereal-based diets — and between high and low-status individuals within the same society based on their diet.

·      Nutritional deficiencies can also be detected from the appearance of bones. Curved leg bones indicate a lack of vitamin D during childhood. Holes in bones can indicate anaemia, indicating a lack of green vegetables or red meat. Flat bones show a diet deficient in protein.

·      Harris lines. These are calcium formations related to periods of arrested growth during childhood or adolescence, commonly because of illness or malnutrition. Harris lines are most evident in the lower shin bone.

·      Height. This can be a good indicator of a good diet and standard of living, as exemplified by skeletal remains from Herculaneum.

Disease and Healthcare 

The types of diseases and injuries that affected individuals or a significant portion of the population of an ancient society can spotlight the environmental and cultural factors that contributed to health issues — and the level of medical care available in the community. 

Visual clues on human bones can provide this information in the following ways: 

·      Stresses on different bones can indicate everyday activities performed in an individual’s lifetime. For instance, deformed ankle bones indicate constant squatting, whereas degeneration of the lower spine indicates carrying heavy loads.

·      Lesions on bones indicate overuse of certain muscle groups. On arms, this could indicate the frequent use of bows or throwing spears, while on feet, it indicates a lot of running.

· Finally, human bones can give some idea of the levels of healthcare in society. Signs of healing in cases of bone trauma, such as regrowth of bone over a skull fracture or wound, show signs of care.

Certain diseases and conditions can also be detected by analysing human bones:

·      Osteo and rheumatoid arthritis. These conditions are indicated by worn cartilage and signs that bones rubbed together as a result (osteoarthritis) or bone remodelling.

·      Gout. The increased uric acid in the blood that causes gout can be deposited in joints, potentially causing the erosion of the joint surfaces. Associated with a rich diet, signs of gout could indicate a high-status individual. 

·      Infectious diseases. Leprosy, TB and syphilis show up most clearly in human bones, with leprosy eroding the bones of the face and syphilis leaving a pitted bone structure. 

• Cancer. Cancer may not be immediately visible in a skeleton but can be identified using CT scans and X-rays. The analysis of 143 skeletons buried in Cambridge allowed archaeologists to establish that cancer was not just a relatively modern disease but also prevalent in the medieval period.

·      Congenital disabilities such as scoliosis spina bifida and Sprengel Deformity also appear in the bones.

Teeth also offer a wealth of information about health, hygiene and habits:

• Cavities can indicate a high-carb/sugar diet. Comparisons of the teeth of individuals from various periods can show how diet has changed.
• Dental attrition can indicate a coarse diet — perhaps from flour infected with grit from the stones used to mill it. 
• Eroded surface enamel could also indicate attempts to brush the teeth with abrasive substances such as chalk, salt or charcoal. Likewise, a build-up of dental calculus can indicate poor dental hygiene.
• Teeth can also act as indicators of social habits, such as pipe smoking or using the teeth to hold twine during primitive manufacturing.

  Death

Signs of disease and unhealed injuries can be signs of the cause of an individual’s death. However, the exact circumstances of death are hard to establish solely based on bone evidence. For example, unhealed blunt or sharp force trauma could indicate death by violence — in war or murder. However, not all bone damage is deliberate or violently inflicted, with many bone fractures caused by falls or accidents.

Apart from the evidence of violence or disease, other features can indicate the cause of death. For instance, the colour of bones from Pompeii offers clues as to the exact nature of death for the victims of Vesuvius.

Relationships, Identity and Appearance

Bones can help identify the relationship between individuals within an ancient community — or link them to their descendants. 

DNA from the Greyfriars skeleton was one of the pieces of evidence used to establish the skeleton’s identity as Richard III by comparing it with DNA from the Plantagenet king’s modern relatives. 

Bones can also be used to establish appearance. Besides his DNA being used to show his modern descendants still lived within the area, Cheddar Man’s DNA also supplements a facial reconstruction of his skull to show that he had blue eyes and dark skin — providing valuable information about the timeline of the evolving features of early Europeans.  

Finally, human bone analysis can help build up a picture of patterns of migration and the interconnectivity of ancient communities. For example, Egtved girl’s DNA shows she was a migrant from a completely different European community to the one where she spent the last years of her life. 

Resources

Archaeology: An Introduction (1995) Kevin Greene. B T Batsford Limited. London

Archaeology: Theories, Methods and Practice (1994) Colin Renfrew and Paul Bahn.Thames and Hudson

Analysing the bones: what can a skeleton tell you?Human Bone Proteomes before and after Decomposition: Investigating the Effects of Biological Variation and Taphonomic Alteration on Bone Protein Profiles and the Implications for Forensic Proteomics