Physical Ageing Using Ectocranial Suture Closure of the Skull - Research Paper Example

Name: Tutor: Title: Physical Ageing Using Ectocranial Suture Closure of the Skull Course: Date: Physical Ageing Using Ectocranial Suture Closure of the Skull Introduction Examination of bones has proven to be a very important instrument in forensic anthropology. This examination has been found useful in determining the age of a skull, its race, sex and even stature. According to White et al (2012), this use of human osteology has been found useful when trying to identify the recently deceased and this has to be done legally. This is categorized as forensic osteology. Byers (2002) argues that the study of human bones can also be applied in historical contexts, where the context could be ancient hence purely paleontological; (like the case of pre-cultural hominids called Pliocene in Africa). The historical context could also be recent and used as part of a record for archeology. An example of this is the chroniclization of human bones which was done a few hundred years ago at the Aztec centers (Mexico) by the Spanish while conquering Mexico. This kind of archeological research gives a lot of information on the cultural residues of the former human existence. Further, the study of human skulls has developed and according to White et al (2012), it has attained a fashionable name, bioarcheology. When used in carrying out investigations, matches may be found between unknown remains and individuals who are missing. According to Rhine (1998), bones do not lie. The analysis of bones can therefore be used as a very important tool in establishing origins and the existence of people and even culture. This paper will investigate the technique of physical ageing using Ectocranial Suture of the Skull. It will explain how the technique can be achieved including its reliability, advantages and disadvantages and a projection on its future. Methodology Determination of age of an individual or animal at death was boosted by the presentation of a new method which is reliant on the degree of closure of the suture. Meindl and Lovejoy (1985) stated that this method uses a simple Ectocranial specific site scoring on an external table. From tests carried out on 236 crania obtained from a collection of Hamann-Todd, lateral anterior sutures are found to be more superior to vault sutures. It was also found out that the ectocranial was superior to the endocranial and that estimation of age was not dependent on race and sex. These findings led them to conclude that closure of the suture could be used to provide estimates of a sample’s age at the time of death in both forensic and archeological contexts if combined with other indicators of skeletal age. The main purpose of this technique is to study the state of skull sutures as they close at definite points located on the cranium. According to Bryson (2011), a complete skull will give two ages; one from values of ectocranial vault sutures while the other from figures of the suture of ectocranial Lateral Anterior. Examination of skull sutures is done at the following 10 points: Mid lambdoid, lambda, obellion, anterior sagittal, bregma, mid coronal, pterion, sphenofrontal, inferior sphenofrontal and superior sphenofrontal. The lengths of the points should be taken at 1 cm and a numerical value assigned as per the stage of closure. The relations of the numerical value and the stage of closure of the sutures are as indicated below: 0- No ectocranial closure observed at site 1- Minimal closure; small to moderate closure (from one bony bridge to 50 % site synopsis) 2- Significant closure; a marked degree though some portion is not totally fused. 3- Total obliteration; the site is fused completely. From the scoring system above, the observer needs to make a significant judgment and choose between scores 1 and 2 for any site with considerable activity. From the experience of Meindl and Lovejoy (1985), they concluded that it is not difficult to make that judgment in all cases, with the exception of a few. It was also found out that the system is very repeatable from observer to observer. Research findings Most studies on cranial suture have their base on the degree of obliteration. According to Kirk (2007), the first observations of cranial suture closure were traced back in the 1st century in some work by Hippocrates. However, they were not used as identifications for age. Kirk (2007) further states that credit should be given to Vesalius, together with his pupil Fallopius because they noted the development of suture obliteration with age. The development of this concept of cranial suture closure was given positive boosts and further studies done because many believed that there had to be something to it since a lot of studies had been done already. This came despite criticism on its feasibility. Key et al (2004) carried out an experiment on 183 skulls. These were from Spitalfields, London. They were observed both endocranially and ectocranially. Four areas of the skeleton were used; pubic symphysis, humeral head, femoral head and the endocranial sutures. Later, the ectocranial sutures were also observed and it was found out that endocranially, ossification occurred earlier as compared to ectocranially. Upon splitting of crania into 5 year age groups, there was a uniform trend which started with a rapid closure and then gradually slowed down with time. To further advance this technique, Key et al (2004) introduced a new method where 70 % of the ages were found to be accurate. Zambrano (2005) observed 388 crania. These were from three different collections of skeletons and were both documented and forensic. From the scores, 18 were recorded for ectocranial, 7 for endocranial, 2 for facial and 4 were recorded for landmarks from palatal suture. Analysis of results indicated that degeneration equations that accurately evaluated a great number of landmarks showed a continuous variation of actual populations. However, the equations used showed some great degrees of errors but Zambrano still concluded that the general trend of the regression equations indicated a relation between age and closure of cranial sutures. Despite the fact that modifications have been made in the studies done on cranial suture closure and its relation to age, the methods have been seen to be traditional since even the most recent studies still using the same framework as that used in the 19th century. According to Lynnerup et al (2003), these studies were dependent on qualitative observations made on the degrees of closure of sutures and analysis of non-parametric relations done between the discreet observation values. An example is given of Meindl and Lovejoy’s (1985) analysis where a score of 1 represents ‘about 50 %’ synostosis while that of 2 represented the degree of closure. Kirk (2007) argues that the difference between these two scores gives a significant judgment, although the authors still believe in the high repeatability of the system; basing on the fact that observers recorded a small number of contrasting scores. Buikstra et al (2003) argued that this brings to question the reliability of the technique since the ‘about 50 %’ synostosis cannot be clearly observed qualitatively. It is further argued that there is no much difference between 51 % and 49 % to the human eye. As for the score of 2, the purported ‘marked degree of closure’ is also not clear to an observer. It could lead one to the assumption of it being between 50 -100 %. Despite these, developments in technology have facilitated the discovery of new ways of carrying out research on closure of sutures and therefore collection of data can now be done efficiently and from various perspectives. According to Lynnerup and Jacobsen (2003), even the advent of new technological methods cannot prevent unbiaseness from occurring. They argue that scoring systems have often been subjective and that locating suture sites is difficult. They therefore proposed that use of fractal geometry might be more light-shedding. Calculations were done on fractal dimensions of sutures of coronal and sagittal from 31 white crania whose ages were known. A tape was placed over the sutures and used to take dimensions and a digitizer was used to input the traces. The fractal dimensions were correlated though none of them was seen to relate with age. The future of this technique is still under exploration as further developments were tried by Singh et al (2004) by use of CT scans, though they still could not get accurate and precise closure of the sutures. Another new method of estimating age out of closure of cranial suture has been introduced by Kirk (2007). It involves use of laser instrumentation in quantification of the magnitude of reflected light from the skull’s ectocranial surface. This device is accurate because laser reading from within the sutures are higher than from the surrounding bone. This new invention found out that as the sutures obliterate and begin to resemble the surrounding bones, scores of the laser decrease, approaching those found at Y points (scores revealing a reading pattern for lasers). These scores at Y points are consistent and relate well with the suture scores and with one another (Moore et al, 2005). Advantages Disadvantages Simple to carry out, since it is based on observation of the closure on the skull and tallying with the scores, Not very reliable since comparison of closure and score might be very close, hence difficult for the human eye to tell the difference, Has shown repeatability of results from past experiments done hence ease of comparison of findings. Location of suture sites on the skull is difficult Conclusion of the findings is an estimate of the real age; the 50 % synopsis of the scores cannot be analyzed qualitatively Conclusion Use of the closure of ectocranial suture for age determination has been investigated for a long time and the findings have been almost similar. Despite arguments that the technique is unreliable, most authors still believe it has a bearing in age determination. This, probably, is the reason behind the many research work being done on it. Issues of inconsistency have been the main concern but with further development of the laser technique, there clearly is some light at the end of the tunnel. Bibliography Bryson David, 2011, Teaching Forensic Anthropology with a small skeletal collection, Cladonia Resources, UK. Buikstra et al, 2003, Forensic Anthropology and Bioarchaeology in the American Anthropologist: Rare but Exquisite Gems, American Anthropologist 105(1):38-52. Byers, N. Steven, 2002, Introduction to Forensic Anthropology: A Textbook, Allyn and Bacon, Boston. Key et al, 2004, Cranial Suture Closure and its Implications For Age Estimation, International Journal of Osteoarchaeology 4(3): 193-207. Kirk D. Jason, 2007, Cranial Suture Closure: A Quatitative Method For Age Estimation Using Laser Instrumentation, Wichita State University. Lynnerup and Jacobsen, 2003, Brief Communication: Age and Fractal Dimensions of Human Sagittal and Coronal Sutures. American journal of physical anthropology 121: 332-336. Meindl and Lovejoy, 1985, Ectocranial Suture Closure: A Revised Method for the Determination of Skeletal Age at Death Based on the Lateral-Anterior Sutures, Ohio, USA. Moore et al, 2005, Estimating age for Cranial Suture Closure Using Laser Instrumentation. Paper Presented at the Annual Meeting of the Midwest Bioarchaeology and Forensic Anthropology Association, Terre Haute, October 8. Rhine, Stanley, 1998, Bone Voyage: A Journey in Forensic Anthropology, University of New Mexico Press. Singh et al, 2004, Age Estimation in Old Individuals by CT scan Of Skull. Journal of Indian Academy of Forensic Medicine 26 (1):10-13. White et al, 2012, Human Osteology, 3rd Ed, Elsevier Inc. USA. Zambrano J. Carlos, 2005, Evaluation of Regression Equations Used To Estimate Age at Death from Cranial Suture Closure, M.S. Thesis, University of Indianapolis. Read More