Estimating the post-mortem interval using accumulated degree-days in a South African setting

Providing a presumptive identification of badly decomposed or skeletonized remains is the responsibility of a forensic anthropologist. An important component of identification is the estimation of a post-mortem interval (PMI) for the deceased. This information can: provide a window period for death, reduce the number of potential victims, exclude possible assailants and substantiate witness testimony. Due to a large number of open and relatively desolate fields in South Africa, human remains are frequently discovered in an advanced stage of decomposition. The aim of this study was to evaluate the usability of the method of Megyesi and associates (2005) in which Total Body Score (TBS) and Accumulated Degree-Days (ADD) were retrospectively applied to estimate the post-mortem interval (PMI). To achieve this, a longitudinal examination of quantitative variables, TBS and ADD, was conducted over a period of 8 months. This period included both summer and winter seasons. Scatter plots between TBS and PMI, and TBS and ADD were used to illustrate patterns in decomposition. Patterns of decay differed in winter and summer, with winter exhibiting distinct inactivity. Using Loglinear Random-effects Maximum Likelihood Regression, the r2 values for ADD (0.6227) and PMI (0.5503) for combined seasons were less than r2 values for separated seasons (ADD 0.7652; PMI 0.7677). In contrast to other studies, seasonality influenced the ADD model and PMI. Linear regression formulae for ADD and PMI as well as 95% confidence interval charts for TBS for ADD were developed. These equations, along with data from a local weather station, can be used to estimate the PMI with relative accuracy. AFRIKAANS : Verskaffing van 'n vermoedelike identifikasie van erg ontbinde of skeletale oorskot is die verantwoordelikheid van ‘n forensiese antropoloog. ‘n Belangrike deel van identifikasie is die beraming van ‘n post-mortem interval (PMI) vir die oorledene. Hierdie inligting verskaf 'n venster tydperk van dood, verminder die aantal potensiële slagoffers, sluit moontlike aanvallers uit en ondersteun getuienis. As gevolg van 'n groot aantal relatief verlate en oop velde in Suid-Afrika, word menslike oorskot dikwels aangetref in ‘n gevorderde stadium van ontbinding. Die doel van hierdie studie was om die bruikbaarheid van die metode van Megyesi en medewerkers (2005) wat gebruik maak van Totale Liggaams Telling (TLT) en Opgehoopte Graad-Dae (OGD) om die postmortem interval (PMI) te skat, terugwerkend te evalueer. Hiervoor was 'n longitudinale studie van kwantitatiewe veranderlikes, TBS en ADD, oor ‘n tydperk van 8 maande gedoen. Hierdie tydperk sluit beide somer en winter in. Verspreidingsgrafieke tussen TBS en PMI, en TBS en ADD is gebruik om patrone in ontbinding te illustreer. Ontbindingspatrone het verskil tussen winter en somer met duidelike onaktiwiteit in die winter. Logliniêre Tweekansige-effek Maksimum Waarskynlikheid Regressie was gebruik om die r2 waardes van die gekombineerde en geskeide seisoene te bepaal. The r2 waardes vir die OGD (0.6227) en PMI (0.5503) vir gekombineer seisoene was minder as die r2 waardes vir seisoene apart (OGD 0.7652; PMI 0.7677). In teenstelling met ander studies, het seisoenaliteit die OGD model en PMI beinvloed. Lineêre regressie formules vir OGD en PMI sowel as 95% vertrouensinterval kaarte vir TLT vir OGD was saamgestel. Hierdie formules saam met data vanaf ‘n plaaslike weerstasie kan gebruik word om die PMI met relatiewe akkuraatheid te skat.Dissertation (MSc)--University of Pretoria, 2010.Anatomyunrestricte

The taphonomic effects of long-term burial in the South African Highveld

Taphonomy studies the environmental effects on remains from the time of deposition to the time of recovery and has been integrated into the field of forensic anthropology. The changes to skeletal remains are dependent on the method of disposal and the surrounding environment. This study focused on buried remains where the type and chemical composition of the soil and the microorganisms present need to be considered. The aim was to investigate the type, frequency, and correlations of the taphonomic alterations of buried domestic pigs. Six taphonomic alterations were observed which included depositional staining, adipocere formation, bone weathering, acidic soil corrosion, and plant, and animal activity. Depositional staining, weathering and plant activity were the most common alterations followed by adipocere which was present on 92.3% of the remains. The bones were mostly stained dark brown and brown; however, the trunk region was the only region to present with black staining. The right sides were darker than the left due to the body positioning as most pigs were placed on their right sides and thus were in direct contact with the cadaver decomposition island. Additionally, the right sides presented with more adipocere as well as increased plant activity suggesting that the soil retained water. Darker stains were correlated with a more complete skeleton as adipocere provides some protection. The study confirms that there are various complicated relationships between different taphonomic alterations. A good understanding of them is needed in forensic anthropology to assist in reconstructing the events that occur after death.The National Research Foundation (NRF) in South Africa as well as the J.J.J Smieszek Fellowship award. Open access funding provided by University of the Witwatersrand.http://link.springer.com/journal/414hj2024AnatomyNon

Scoring of decomposition : a proposed amendment to the method when using a pig model for human studies

Decomposition studies often use pigs as proxies for human cadavers. However, differences in decomposition sequences/rates relative to humans have not been scientifically examined. Descriptions of five main decomposition stages (humans) were developed and refined by Galloway and later by Megyesi. However, whether these changes/processes are alike in pigs is unclear. Any differences can have significant effects when pig models are used for human PMI estimation. This study compared human decomposition models to the changes observed in pigs. Twenty pigs (50–90 kg) were decomposed over five months and decompositional features recorded. Total body scores (TBS) were calculated. Significant differences were observed during early decomposition between pigs and humans. An amended scoring system to be used in future studies was developed. Standards for PMI estimation derived from porcine models may not directly apply to humans and may need adjustment. Porcine models, however, remain valuable to study variables influencing decomposition.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1556-40292018-07-30hj2017Anatom

Comments on Mpeta et al. (2018): Black living standards in South Africa before democracy

Mpeta et al. recently published a paper in which they used secular trends in stature of South Africans to make inferences about living standards. The use of documentation of living standards and the fluctuations thereof as a result of economic growth to explain the secular changes observed in height is a viable approach. The authors gave an excellent review of the history of South Africa and the differences in living conditions that existed between the population groups. However, we believe the biological data were incorrectly used, in order to support inferences regarding the socio-economic situation. The average stature of a population group indeed has a direct relationship with the living conditions and the per capita income of the individuals. For example, decreased stature may be an indicator of nutritional deprivation as a result of a lower income. However, it is important to note that there are many other factors that can influence stature. The size and shape of human bodies vary considerably among population groups across the world and body size is not fixed. Changes in height are continually taking place. In this study the authors repeatedly imply that the living standards can be explained by differences and changes in height, e.g. ‘by analysing the mean height…, we shed light on the standard of living’ (p. 1); ‘black living standards as measured by height’ (p. 1). Height should not be used simplistically to indicate the standard of living or socioeconomic status as it is influenced by too many other variables such as climate, diet, genetics/gene flow, family size and urbanisation. Rather, standard of living should be used, as one of many possible factors, to explain the observed differences in height.http://www.sajs.co.zaam2019Anatom

Identifying forensically relevant urban scavengers in Johannesburg, South Africa

Presented in part at the American Academy of Forensic Sciences 72nd Annual Scientific Meeting in Anaheim, California, USA (17-21 February 2020), and at the 48th Annual Conference of the Anatomical Society of Southern Africa in Durban, South Africa (19-21 April 2021).Unidentified human remains are frequently recovered in urban environments in South Africa, which undergo forensic (medico-legal) investigations. These remains often exhibit animal scavenging modifications and are frequently scattered by animals. This impacts the collection and forensic analysis of the remains. This study aimed to identify scavenging animals present in two urban environments in Johannesburg, South Africa, and describe their scavenging and scattering behaviours. Six pig carcasses (Sus scrofa domesticus) (30–80 kg) were placed in a veldt in Johannesburg and in an abandoned building complex. Motion-activated cameras recorded the scavenging activities. Scavenger species were identified and their behaviours, scattering pattern, and scavenging bone modifications were described. Slender mongooses (Galerella sanguinea) were the most prolific veldt scavengers. They scattered remains to a maximum distance of 10.5 m in two directions: north and southeast. These mongooses scavenged during the advanced and dry decomposition stages. Gnawing on the angle of the mandible - with multiple parallel scores on the flat surfaces and the angle margin having a stepped appearance - may be a distinguishing scavenging modification feature of the slender mongoose. Hadeda ibis (Bostrychia hagedash) were the only scavengers recorded scavenging on the intestines of a pig carcass in the abandoned building complex. They favoured colonizing insects and created multiple, large holes in the skin and removed the lips to access the insects. The described scavenging behaviours will assist in the reconstruction of postmortem events in forensic cases and the location and collection of scattered remains in Southern Africa.National Institute of Justice and the Forensic Technology Center of Excellence along with the American Academy of Forensic Sciences Humanitarian and Human Rights Resource Center.http://www.elsevier.com/locate/scijushj2023Anatom

Animal scavenging on pig cadavers in the Lowveld of South Africa

Scavenging animals often scatter skeletal remains of forensic interest and leave bite marks. This study aimed to identify scavenging animals in the rural Lowveld of South Africa and to describe their scattering pattern and bite marks on bone. Ten pig cadavers (Sus scrofa domesticus) (40–80 kg) were placed at the Wits Rural Facility, Limpopo, South Africa during the summer and winter seasons. Motion activated cameras recorded the scavenging. Scavenger species were identified and their behaviors, scattering pattern, and bite marks were described. Scavenging was primarily by vultures (hooded, white-backed, and lappet-faced). Marabou stork, slender and banded mongoose, genet, civet, warthog and honey badger also actively scavenged. Vultures began to scavenge the pig cadavers after 18hrs in summer and between 26 and 28 h in winter and skeletonized pig cadavers rapidly between 5 and 98 min. Skeletonization occurred more rapidly and diffusely in summer while winter cases were densely scattered. Overall the scattered remains were within an area of 157.9 m2/1705.5 ft2 with a radius of 7.09 m/23.3 ft. Vultures cleaned bones thoroughly with very minimal markings - primarily nonspecific scores. The described scattering pattern and bite marks will assist in the recovery and analysis of scavenged remains.National Institute of Justice and the Forensic Technology Center of Excellence along with the American Academy of Forensic Sciences Humanitarian and Human Rights Resource Center.https://www.elsevier.com/locate/forsciinthj2022Anatom

Age estimation from the acetabulum in South African black males

Anthropologists are constantly seeking to improve methods for age estimation in the human skeleton. A new method was introduced about a decade ago that assesses the morphological changes that take place in the acetabulum as an individual ages. The pelvis is usually well preserved in forensic cases, which makes this method potentially valuable as an adult age indicator. This method employs seven variables, each with its own set of phases. To test the accuracy and reliability of this method, 100 black South African male acetabula from the Pretoria Bone Collection were assessed based on the criteria described in the original study. Box plots and transition curves were constructed to establish whether progression with age was visible and how it could possibly be modelled. Inter-observer reliability was also assessed by making use of Fleiss’s Kappa statistic. Five specimens were used as out-of-sample examples for which maximum likelihood (point) estimates were calculated. The results demonstrated that middle and older individuals’ age estimates were vastly underestimated. Inter-observer repeatability was poor, which suggested that the classification system most likely needs to be modified. A discussion and recommendation is given for improvement of reliability and repeatability of this method.The National Research Foundation (NRF) of South Africahttp://link.springer.com/journal/4142017-05-30hb201

Estimating the postmortem interval (PMI) using accumulated degree-days (ADD) in a temperate region of South Africa

The validity of the method in which total body score (TBS) and accumulated degree-days (ADD) are used to estimate the postmortem interval (PMI) is examined. TBS and ADD were recorded for 232 days in northern South Africa, which has temperatures between 17 and 28 °C in summer and 6 and 20 °C in winter. Winter temperatures rarely go below 0 °C. Thirty pig carcasses, which weighed between 38 and 91 kg, were used. TBS was scored using the modified method of Megyesi et al. [1]. Temperature was acquired from an on site data logger and the weather station bureau; differences between these two sources were not statistically significant. Using loglinear random-effects maximum likelihood regression, an r2 value for ADD (0.6227) was produced and linear regression formulae to estimate PMI from ADD with a 95% prediction interval were developed. The data of 16 additional pigs that were placed a year later were then used to validate the accuracy of this method. The actual PMI and ADD were compared to the estimated PMI and ADD produced by the developed formulae as well as the estimated PMIs within the 95% prediction interval. A validation of the study produced poor results as only one pig of 16 fell within the 95% interval when using the formulae, showing that ADD has limited use in the prediction of PMI in a South African setting.NRF (National Research Foundation of South Africa) and Navkom (University of Pretoria).http://www.sciencedirect.com/science/article/hb2013ay201

A comparison between decomposition rates of buried and surface remains in a temperate region of South Africa

Several studies have been conducted on decomposition patterns and rates of surface remains; however, much less are known about this process for buried remains. Understanding the process of decomposition in buried remains is extremely important and aids in criminal investigations, especially when attempting to estimate the post mortem interval (PMI). The aim of this study was to compare the rates of decomposition between buried and surface remains. For this purpose, 25 pigs (Sus scrofa; 45–80 kg) were buried and excavated at different post mortem intervals (7, 14, 33, 92, and 183 days). The observed total body scores were then compared to those of surface remains decomposing at the same location. Stages of decomposition were scored according to separate categories for different anatomical regions based on standardised methods. Variation in the degree of decomposition was considerable especially with the buried 7-day interval pigs that displayed different degrees of discolouration in the lower abdomen and trunk. At 14 and 33 days, buried pigs displayed features commonly associated with the early stages of decomposition, but with less variation. A state of advanced decomposition was reached where little change was observed in the next ±90–183 days after interment. Although the patterns of decomposition for buried and surface remains were very similar, the rates differed considerably. Based on the observations made in this study, guidelines for the estimation of PMI are proposed. This pertains to buried remains found at a depth of approximately 0.75 m in the Central Highveld of South Africa.http://link.springer.com/journal/4142019-01-12hj2018AnatomySchool of Health Systems and Public Health (SHSPH)Statistic

Secular trends in stature of late 20th century white South Africans and two European populations

During the 20th century a general positive secular trend for stature is observed in developed countries around the world while shorter statures, often associated with a lack of a positive secular trend, have mostly been observed in populations with lower SES. The purpose of this study was to compare secular changes in stature between 20th century South Africans of European descent and two European populations. The comparative samples include Dutch males with which there is an assumed genetic relationship, and Swiss males for which the genetic association is less clear. The sample comprised anthropometric stature data of white South Africans (17–62 years), Swiss and Dutch males (18–21 years) obtained from military conscripts with birth cohorts of 5 years from 1946 to 1995. The stature of white South African males did not increase at a significant rate compared to those observed in Swiss and Dutch males. South African and Dutch males were of similar height following World War II, but a considerable trend was observed only in the Dutch group. The Swiss group was initially shorter than the South Africans, but due to a positive secular trend their average stature is on a par with that of South Africans in the most recent cohort. The lack of a significant positive secular trend in the South African group could suggest that factors such as gene flow and poor economic and social development in South Africa resulted in shorter statures in white South African groups than expected.The National Research Foundation (M. Steyn) and the Department of Anatomy at the University of Pretoria.http://www.elsevier.com/locate/jchb2018-12-30hj2018Anatom