5
J. Forens. Sci. Soc. (1974), 14,209 Estimation of Age from Skeletal Remains A. A. WATSON Department of Forensic Medicine, Uniuenil?j of Glasgow, Glnsgow G12 8QQ Scotland The expert confronted with skeletal remains is usually asked to giue an estimate of both fhe date oJ' death and the age of the indiuidual at the time of death. This Paper presents a brief revierel of the methods available to make these two estimates. Introduction With the continuing expansion in the national building programme and in road developn~ent throughout this country, human skclctal remains arc frequently unearthed. They are uncovered in most unusual sites and at variable depths. Unless the site is known to be that of an early burial ground and thcrcfore of antiquarian nr archaeological interest, the police are usually in- formed of the discovery of the human rrmains. They are then conveyed to the forensic pathologist with the request-"examine the bones and estimate their age." Such a request involves two questioils: (a) How long is it since death occurred? (b) What was thc agc of the person at death? The Date of Death The determination or the date when thc boncs wcrc interred-usually the same time as death occurred-is frequently very diflicult to estimate, because so rarely is there any collatcral cvidencc to confirm onc's results. In a recently unearthed grave near Cambridge, containing two male skeletons which I examined, collateral evidence was available in the form of crudely fashioncd coffin nails and sevcraI large pieces of pottery. Archaeological studies supported the view that the lattcr werc locally fired and, strengthened by the knowledge that the grave was alongside a well-known Roman road and in proximity to a Romano-British settlement, the age of the grave and that of thc skeleton could be reasonably fixed as between 150-250 A.D. It is of inlportance to attempt to estimate the age of any unearthed bones because the police, the procurator-fiscal or thc coroner will want to know whether the remains are recent. enough to warrant undcrtaking further enquiries, or whether being so old they are of sole interest to the archaeologists. The dividing line is usually taken to be in the region of 50 years, but some inquisitors may raisc this to 75 ycars, or even slightly higher. But if the bones are oldcr than 50 ycars thcn thcy bcconlc of littIe interest to the law enforce- ment agencies. It is reasonable to assume that if from a study of the remains there exists the possibility that a homicide had taken placc, thc likelihood is that the perpetrator of the deed will probably also be dead. How long since death ? There are so many factors to be taken into considera- tion that the end result is little more than an inspired guess. Much will depend on where the remains have bccn lying over thc years. - The preservation of bones varies considerably not only from soil to soil, but also, becausc of minor soil differences, from one burial area to another. A knowlcdgc of the soil structure and its constitution is most helpful in arriving at one's conclusion (Brothwell, I 972). In permeable gravel soils, where the acidity is high, the bones are poorly preserved, in contrast to the anaerobic, watcrlogged, peaty gravel conditions where the bones are dark-brown stained with well preserved skullq. In chalky

Estimation of Age from Skeletal Remains

Embed Size (px)

Citation preview

Page 1: Estimation of Age from Skeletal Remains

J. Forens. Sci. Soc. (1974), 14,209

Estimation of Age from Skeletal Remains

A. A. WATSON Department of Forensic Medicine, Uniuenil?j of Glasgow, Glnsgow G12 8QQ Scotland

The expert confronted with skeletal remains is usually asked to giue an estimate of both fhe date oJ' death and the age of the indiuidual at the time of death. This Paper presents a brief revierel of the methods available to make these two estimates.

Introduction With the continuing expansion in the national building programme and in

road developn~ent throughout this country, human skclctal remains arc frequently unearthed. They are uncovered in most unusual sites and at variable depths. Unless the site is known to be that of an early burial ground and thcrcfore of antiquarian nr archaeological interest, the police are usually in- formed of the discovery of the human rrmains. They are then conveyed to the forensic pathologist with the request-"examine the bones and estimate their age."

Such a request involves two questioils: (a) How long is it since death occurred? (b) What was thc agc of the person at death?

The Date of Death The determination or the date when thc boncs wcrc interred-usually the

same time as death occurred-is frequently very diflicult to estimate, because so rarely is there any collatcral cvidencc to confirm onc's results.

In a recently unearthed grave near Cambridge, containing two male skeletons which I examined, collateral evidence was available in the form of crudely fashioncd coffin nails and sevcraI large pieces of pottery. Archaeological studies supported the view that the lattcr werc locally fired and, strengthened by the knowledge that the grave was alongside a well-known Roman road and in proximity to a Romano-British settlement, the age of the grave and that of thc skeleton could be reasonably fixed as between 150-250 A.D.

I t is of inlportance to attempt to estimate the age of any unearthed bones because the police, the procurator-fiscal or thc coroner will want to know whether the remains are recent. enough to warrant undcrtaking further enquiries, or whether being so old they are of sole interest to the archaeologists. The dividing line is usually taken to be in the region of 50 years, but some inquisitors may raisc this to 75 ycars, or even slightly higher. But if the bones are oldcr than 50 ycars thcn thcy bcconlc of littIe interest to the law enforce- ment agencies. It is reasonable to assume that if from a study of the remains there exists the possibility that a homicide had taken placc, thc likelihood is that the perpetrator of the deed will probably also be dead.

How long since death ? There are so many factors to be taken into considera- tion that the end result is little more than an inspired guess. Much will depend on where the remains have bccn lying over thc years. -

The preservation of bones varies considerably not only from soil to soil, but also, becausc of minor soil differences, from one burial area to another. A knowlcdgc of the soil structure and its constitution is most helpful in arriving at one's conclusion (Brothwell, I 972).

In permeable gravel soils, where the acidity is high, the bones are poorly preserved, in contrast to the anaerobic, watcrlogged, peaty gravel conditions where the bones are dark-brown stained with well preserved skullq. In chalky

Page 2: Estimation of Age from Skeletal Remains

soil because of its ~riarkedly permeable nature, bones may show a considerable degree of erosion and the bone substance is very fragile. Clay soil is unpre- dictable. I t may cause bone erosion through acidity, or, where the subsoil is marl, the bones may be surprisirigly well preserved. Sand is similar to gravel. Where it is loosely structured the pH value or acidity is variable. Thc sandy soil at Mauer in Germany, whcre thr fossil jaw of I-Ieidelberg Man was located, has a high pH, and the bone preservation is good. The presence of ligarrients and cartilage suggests a relatively recent death, but usually more than a year. Periosteum adheres to thc bones for several years and is fi+equently seen on boncs buried lip to ro years or more. Later than lo years there may be associated with the bones a trace of the odour of decay. This odour survives for varying lengths of time and depends on climatic factors. I t is a reasonable indication of relatively recent dcath (Catnps, r 968).

When the bones have beeri derluded of covering soft tissues and the decaying odour has been lost thcrc is a white-yellow fresh appearance to the bone surface which contrasts to the yellow-brown colour of lung-buried specimens. On cut- surfacc the latter have a chalky, brittle texture. Biocl~emical Examination. There arc several biochemical tests which can bc used but they are only of usc in tcrms ol'decades, and although they are sensitive tests per se, they are nevertheless not date-specific. Carrips and Purchase ( I 956), Berg (1463)~ and Knight (1967, 1969) have laid down a numbcr of practical lines of invcstigatinn which a forensic labot*atory could profitably pursue. Knight, who has published the teclir~iraI details has concluded that the following cri~eria are of substantial value : Benzidine reaction. Benzidinc testing, with appropriate attcntion to details, giving reliable, consisten1 results car1 be obtained fiorn the periosteurr~ and bone dust fro111 the cortex. The test appears to be positive for about 100-150 vears. Hunzalz pr-eciflitin reactinrzs are of only limited value. Knight showed that using a gel diffusion technique, the test gave positive results for only up to about 5 ycars aftcr dcath. Nitrogen conlent. Using a rnicro-K,jeldhal method the nitrogen content is of value for relatively old bones. If the nitrogen content is less than ~ - 5 g q ' ; ~ then thc bonc is morc than 350 ycars old. Bone less than 50 years old shows a nitrogen content of morc than 3*5g','l;. Herg ( I 963) arrived at a similar conclusion. Thin-layer chromatograplly. When bone has been digested in hot hydrochloric acid the stromal proteinsare broken downinto amino-acids. Knight ( I 969) showed that the amino-acid uattcrn could be dctnonstratcd on thin-laver chronlato- graphy. If the bone is less than 70 years old, seven or even Inore amino-acids are recoverable. Beyond that date the number decreases steadily. Proline and hydroxyproline arc both present up to 50 years. Ultraviulel Juorescence. If a fkeshly cut surface of 5 lirrtb bone is exa~nined, fluorescence is total for bones up to roo years old. Beyond this date, Knight claims, thcrc is a gradual peripheral loss of' fluoresccncc up to a complctc loss by about 500 years. Radiocarbon datirg o f Bone. When adequate quantities of bone are available, the residual protein in the bone can sometimes be dated by this method. I t is a very expensive technique and has only occasionally been used for dating human bones, mainly because in working with specimens, it involves destruc- tion ofsomc of the tissue. It was used in dating the Piltdown skull, which was shown to be probably marc than I ,ooo ycars oId (dc Vrics atld Oaklcy, 1959). The method becomes more precise in its calculations when applied to wood and charcoal, and thcreforc if prcscnt with the boncs, they col~ld bc used as in- direct means of dating the honcs (Brothwell, 1972).

In sunlrnary, the estinlation of the age of unearthed bones, is not very accurate, so that after having taken into account all available evidence one is eventually led to make an inspired and intelligent guess.

Page 3: Estimation of Age from Skeletal Remains

Determination of Skeletal Age The second question to be answered is: what was the age of the body at

death ? . . . . . . - - .

Assessments of age of skeletal remains can be fairly accurately made from the sixth month of intra-uterine life up to young adulthood, possibly to the age of 25 years. With persons beyond that age there is more of a problem and there is liable to be an error of up to 10 years.

Whilst the most important subject of dental age is fully discussed in an accompanying article, it should be mentioned here that it is possible to cor- roborate dental evidence from the sites of ossification elsewhere in the body. Ossification Centres. I t is estimated that by the end of the first trimester of intra-uterine life there exist about 800 centres of ossification but many gradually fuse and disappear, so that at birth there are some 450 potential centres. Many textbooks on forensic medicine carry tables indicating the sites and times of appearance of the major ossification centres. These are determinable both by radiological examination and by section of the cartilaginous areas in the bones concerned. Some remain identifiable up to the 19th or 20th year when final fusion occurs, the last bones to ossify being the tuberosity of the ischium and the inner end of the clavicle.

For detailed studies radiographical atlasses of skeletal development should be consulted (Pyle and Hoerr 1955, Greulich and Pyle, 1958). Epiphyseal Closures. An additional line of investigation is the process of union between the metaphyses and epiphyses, and between certain flat bones. This begins at about 2 years with the closure of the anterior fontanelles of the skull. At 4 years the greater tubercle fuses with the head of the humerus and thus the process continues inexorably until at about 25 years the crest of the ilium is united with the main ilia1 mass, and the inner ends of the ribs are united with the main ribs.

In general terms, although it is subject to a fairly wide variation, if all the epiphyses are found united, and if all three parts of the sternum are united by bone then the body is almost certainly 35 years. The need for radiological confirmation is most important. In the female the fusion occurs usually a year or two earlier than in the male. The accuracy is increased by the examination of many bones, for the fewer the bones scrutinized, the greater the error in the final estimation. Where the deceased was over 25 years at the time of death, it is really a problem for the anatomist working jointly with the palaeopathol- ogist or the forensic pathologist.

Apart from the union of the sternal bones during the decade after 25 years, the ape of the bones is estimated from the skull and the ~elvis.

0

Skull. During the process of ageing, the serrated sutures which separate the flat bones of the cranium gradually become obliterated as one bone fuses with its neighbour. This occurs, at different times, both on the outer surface (ecto- cranium) and on the inner table (endocranium). Because the closure is very slow the relationship of its rate to ageing has been studied over several centuries. The degree of reliability has frequently been closely studied by anatomists (Parsons and Box, 1905 ; Todd and Lyon, 1924; 1925). The age range has been estimated from 20 years up to 50 years, when all cranial sutures are usually obliterated.

Recently the value placed on these assessments has been criticised, (Singer, 1953; Cobb, 1955 ; and Krogman, 1962). Krogman expressed it "estimation of age of the skull via suture closure is not reliable", but implied that if that was all that was available for study he would be able to estimate the age to within a particular 1 0-years age range. Pelvis. Whilst the various ossification centres in the pelvis are of value for the first two decades, recent attention has been paid to the development and late changes to the pubic symphysis. By using the changes of the symphyseal face Todd (1920, 1921) was able to extend the age determination well into the later decades.

Page 4: Estimation of Age from Skeletal Remains

A most important progressive contribution to the study of symphysial changes with age has been made by McKern and Stewart (1957) based on the remains of American soldiers killed in Korea. The system divides up the pubic sym- physis into three major components each having five active stages. There is an inter-related system involving both parameters which is used to evaluate any particular case. They were able to estimate the ages from 17 years up to 40 years. As before, the services of an experienced anatomist are required to decide the various categories involved. Humerus. Several workers have reported on the pattern of bone resorption from the cancellous tissue at the upper ends of long bones. The humerus shows the changes particularly well both on radiological examination and on longi- tudinal section. The work of Schranz (1959) is worthy of study and describes the gradual apparent ascent of the medullary cavity towards the surgical neck of the bone in the fifth decade and progressively on towards the epiphyseal line in the sixth and seventh decades. Microscopy on cortical bone. A difficult, but seemingly reliable method, relies on the main structural components of cortical bone viz, whole osteons, circum- ferential lamellar bone and non-Haversian canals, and the encroachment of one on the others. Kerley (1970) with his fine microscopic preparations was able to estimate cortical bone to within 5 years and that on a range of specimens from the second to the ninth decades.

For forensic pathologists and anatomists, presented with a few assorted bones, additional consideration must be paid to signs of degeneration, in the form of erosions, lipping, fusion, osteoporosis, Paget's disease and other changes in the bone. The worker may be many years out in his estimation but at least he will be the first to know of his obvious limitations. Until easier, yet still sophisticated, laboratory methods become available the ageing of skeletal remains will always remain a matter of inspired estimation and a little good fortune.

References BERG, S., 1963, Methods in Forensic Science, Vol. 2, Interscience Publishers,

London. BROTHWELL, D. R., 1972, Digging up Bones, British Museum (Nat. History),

London. CAMPS, F. E., 1968, Gradwohl's Le.cal Medicine, John Wright & Sons, Bristol. CAMPS; F. E.; and PURCHASE, B., 1956, Practical Forensic ~edicine, ~utchinson. COBB, M. W., 1955, The age incidence of suture closure (Abstract), Amer. J.

Phys. Anthrop. (N.S.1, 13, 394. DE VRIES, H., and OAKLEY, K. P., 1959, Radiocarbon dating of the Piltdown

skull and jaw, Nature, London, 184, 224. GREULICH, W. W., and PYLE, S. I., 1958, Radiographic Atlas of Skeletal Development

of the Hand and Wrist, 2nd Edn., University Press, Stanford, California. KERLEY, E. R., 1970, Estimation of skeletal age: after about age 30,

Personal Identification in Mass Disasters, Ed. T. D. Stewart, National Museum of Natural History, Washington.

KNIGHT, B., 1969, Methods of dating skeletal remains, Med. Sci. Law, 9, 247. KNIGHT, B., and LAUDER, I., 1969, Practical methods of dating skeletal remains :

a preliminary study, Med. Sci. Law, 7, 205. KROGMAN, W. M., 1962, The Human Skeleton in Forensic Mediiine, Thomas Ltd.,

Springfield, Illinois. MCKERN, T. W., and STEWART, T. D., 1957, Skeletal Age Changes in Young

American Males, Technical Report, Headquarters Quartermaster Research and Development Command, Natick, Mass.

PARSONS, I?. G., and Box, L. R., 1905, The relation of the cranial sutures to age, J. Roy. Anthrop. Inst., 25, 30.

PYLE, S. I., and HOERR, N. L., 1955, Radiographic Atlas of Skeletal Development of the Knee, Thomas Ltd., Springfield, Illinois.

Page 5: Estimation of Age from Skeletal Remains

SCHRANZ, D., 1959, Age Determinations from the Internal Structure of the Humerus, Am. J. phys. Anthrop. (N.S.), 17, 273.

SINGER, R., 1953, Estimation of age from cranial suture closure, J. For. Med., 1. 52.

TODD, T. W., 1920, Age changes in the Pubic Bone, I : Male White Pubis. Amer. J. phys. Anthrop., 3, 285.

TODD, T. W., 1921, Age changes in the Pubic Bone, 11: Male Negro-White hybrid, 111: Pubis of White Female, IV: Pubis of Female Negro-White hybrid, Amer. J. phys. Anthrop., 4, 1.

TODD, T. W., and LYON, D. W., 1924, Endocranial suture closure, Part I, Adult males of White stock, Amer. J. phys. Anthrop., 7, 325.

TODD, T. W., and LYON, D. W., 1925, Cranial suture closure, Part 11, Ecto- cranial closure in adult males of White stock, Zbid, 8,23.