The use of craniofacial measurements in body size estimation:implications for fossil hominins

This master thesis studies the use of craniofacial measurements in body size estimations using a reference sample of 74 extant African apes and creates new size estimation equations for fossil hominins. Size estimation is one of the most important tools in palaeoanthropology and there are many features reducing the use of postcranial bones in size estimations. As a results, there is demand to study the application of craniofacial dimensions as predictors in the body size estimations. The main focus was to study if some of the craniofacial measurements have strong relationship to skeletal frame size (SFS) which in this study was utilized as a proxy for the body size. These analyses were based on Pearson correlations which were performed separately for sex- and species specific samples. Measurements with the strongest correlations were further utilized to create the equations and size estimations for the apes by applying least square regression and their accuracy were then examined. Further size estimations were computed for 15 fossil skull casts (representing 13 species) that were available in the Zoological Museum of the University of Oulu. In the end these new size estimations for fossil hominins were compared to the previous size estimations of these species to determine how the new equations work in reality and could be used in future research. All the analyses were done with IBM SPSS Statistics. Results from the correlations showed a very strong relationship between craniofacial measurements and SFS. The highest correlations were found with facial size and GIL (r=0.951). Altogether 8 measurements were chosen to be used in the regressions and size estimations. Additionally, it was decided to create own equations for males and females. The results of the linear regressions and size estimations for apes demonstrated promising results, with the smallest MAPE of facial size between 12–14% in all samples and all samples having at least a few equations which produced predictions where 70% of specimens fall within ±20% of the SFS. Although clearly the best results were received using facial size, in general most of the results were comparable to those of previous studies. However, when the fossil cast size estimations were performed it became apparent that majority of the craniofacial measurements would not work as a size predictor. Results included many over- and underestimations but did not differ much amongst the pooled, male or female equations. Only facial size was able to produce fairly accurate estimations and its sole problem seemed to be the very small-sized H. floresiensis. The reasons behind this most like stem from the size range of the reference material which had much larger specimens compared to the fossil hominins. As a result of this study facial size seem very promising size predictor which probably is related to the fact that it represents the overall size of the face instead of just one dimension. However, the use of facial size as body size predictor requires more research. Particular important would be to test its’ applicability with reference material including smaller species and individuals to obtain better equations for smaller hominins.Pro gradu -tutkielmani aiheena on tutkia kallon mittojen käyttöä kokoarvioiden teossa hyödyntäen aineistona 74 yksilön Afrikkalaisen ihmisapinan otosta ja luoda uudet kokoarviointilaskukaavat, joita voisi sitten käyttää fossiili hominien kokoarvioinnissa. Aihe tarvitsee lisäselvityksiä, sillä kokoarviointi on yksi paleoantropologjen tärkeimmistä työkaluista tutkittaessa muinaisia hominineja. On myös ilmennyt monia seikkoja, jotka ovat heikentäneen postcranialisten luiden käyttöä koko-arvioinneissa. Tämä on luonnut tarpeen tutkia kallon mittasuhteiden hyödynnettävyyttä. Tarkoituksena oli ensinnäkin tutkia mitkä kallon yksittäiset mitat osoittavat vahvaa suhdetta luuston kehyskoon kanssa (SFS), joka kuvastaa tutkimuksessa ruumiin kokoa. Yksittäisiä mittoja tutkittiin Pearson korrelaatio analyysin avulla käsitellen lajien ja sukupuoliryhmien välisiä eroja. Tämän jälkeen tehtiin least square regressio analyysi niille mitoille, jotka osoittivat vahvaa korrelaatiota SFS:n kanssa. Tällä tavalla saatiin luotua kokoarviokaavat ja apinoille kokoarviot, joiden paikkansa pitävyyttä sitten tutkittiin. Seuraavaksi laskettiin uudet kokoarviot 15 fossiili kallovalokselle (edustivat 13 lajia), jotka olivat saatavilla Oulun Yliopiston Eläinmuseossa. Lopuksi fossiilien uusia kokoarvioita verrattiin jo olemassa oleviin lajien kokoarvioihin ja selvitettiin kaavojen toimivuutta sekä niiden hyödynnettävyyttä tulevissa tutkimuksissa. Kaikki analyysit tehtiin IBM SPSS Statistics tilasto-ohjelmalla. Korrelaatioiden tulokset osoittavat vahvaa suhdetta kallon mittojen ja SFS välillä. Korkeimmat korrelaatiot saatiin kasvojen koolle ja GIL:le (r=0.951). Kaiken kaikkiaan 8 mittaa valittiin käytettäväksi lineaarisessa regressiossa ja kokoarvioissa. Tämän lisäksi uroksille ja naaraille luotiin omat kokoarvio kaavat. Regressiot ja apinoiden kokoarviot tuottivat hyvin lupaavia tuloksia. Pienin MAPE (12–14 %) löytyi kaikissa otoksissa (kaikki, urokset ja naaraat) kasvojen koolta. Kaikissa otoksissa ainakin muutama laskukaava tuotti kokoarvioita, joista 70 % osui ±20% sisälle SFS koosta. Vaikka selvästi parhaimmat tulokset saatiin käyttäen kasvojen kokoa laskukaavioissa, kokonaisuudessaan suurin osa tuloksista oli samaa luokkaa aiempien tutkimusten tulosten kanssa. Sen sijaan, kun fossiilien kokoarvoit laskettiin, tuli selväksi ettei suurin osa kallon mitoista toimi luotettavina kokoarviojana. Tulokset osoittivat monia koon yli- ja aliarviointeja, mutta eri otoksilla luotujen kaavojen tulokset eivät juuri eronneet toisistaan. Ainoastaan kasvojen koko sai tuotettua suhteellisen tarkkoja arvioita ja sen ainoa ongelma vaikutti olevan pienikokoinen H. floresiensis. Syy tähän todennäköisesti liittyy aineiston yksilöiden kokoon, missä on paljon suurempia yksilöitä verrattaessa homineihin. Tämän tutkimus osoittaa että kasvojen koko vaikuttaa lupaavalta kokoarvioijalta. Tämä liittyy todennäköisesti siihen että mitta edustaa kasvojen kokonaiskokoa eikä vain yksittäistä mittaa. Tästä huolimatta kasvojen koon käyttäminen kokoarvioiden teossa vaatii vielä lisätutkimuksia. Varsin tärkeätä olisi käyttää aineistoa, johon kuuluisi pieniä yksilöitä, jotta saataisi luotua parempia laskukaaviota, joita voitaisiin hyödyntää myös pienempiä homineita tutkittaessa

Comparison of bone density patterns of the subaxial spine between chimpanzees and gorillas:a case study

Abstract Case study on the bone density pattern of subaxial vertebral column in African apes. Introduction: African apes have been noted to experience fewer back ailments than humans and to have higher vertebral bone density. Yet, research on the subject is quite limited and has usually included only one or few vertebrae. However, to understand vertebral column as whole and how posture and locomotion might have affected it, we need to know how bone density varies between adjacent vertebrae. Materials and Methods: Bone density in the vertebral body was measured for all subaxial vertebrae of five specimens including two Pan troglodytes (1 male and 1 female) and three Gorilla gorilla (2 males and 1 female) using peripheral quantitative computed tomography (pQCT). Results: The results tentatively indicated differences between species, especially in the trabecular density of the cervical segment and support the need for further studies on this subject

Sex- and site-specific, age-related changes in bone density:a Terry collection study

Abstract As modern populations are living longer, age-related health issues have become more common. One growing concern is the age-related bone density loss that increases the individual’s risk for fractures, which unfortunately seems to disproportionately afflict women. These fractures are not only detrimental to the individuals’ lives but also come with a great economic burden to the societies. Although age-related bone loss is a normal phenomenon, studies on archaeological individuals have demonstrated that the pattern how this occurs has experienced changes due to our changing lifestyles. Hence, to add to our understanding of secular trends in age-related bone loss, we studied age- and sex-related differences in vertebral and femoral bone densities of a recent past population of late 19th and early 20th century Americans. We used a sample of 114 individuals (55 males, 59 females) from the Robert J. Terry Anatomical Skeletal Collection. Peripheral quantitative computed tomography (pQCT) was used to scan the dry bones. We took one scan from the 4th lumbar vertebra and three scans from the femur. The associations between the age, sex and bone density were analyzed. We were able to detect age-related bone loss in both vertebra and femur. It was observed that men tended to lose more bone density on the vertebra, whereas bone loss in women was more pronounced in the femur. We speculate that differences to modern and earlier archaeological populations are related to the major lifestyle differences between the periods

Estimation of stature from dimensions of the fourth lumbar vertebra in contemporary middle-aged Finns

Abstract Background: Accurate stature estimation plays an essential role in the identification of unknown deceased individuals. For cases in which conventional methods of stature estimation are not applicable, we studied the stature estimation potential of the fourth lumbar vertebra (L4) among a large living sample of representative contemporary Finns. We also generated stature estimation equations for the middle-aged Finnish population. Material and methods: Our study population comprised the Northern Finland Birth Cohort 1966 for which lumbar magnetic resonance imaging (MRI) scans and objective measurements of stature were available from midlife (n = 1358). After screening the MRI scans for vertebral pathologies, we measured the maximum and minimum widths, depths and heights of the L4 body with high precision and reliability. We then calculated their sums and means together with approximations of vertebral cross-sectional area and volume. By constructing simple and multiple linear regression models around the L4 parameters, we generated equations for stature prediction, and investigated their accuracy on the basis of the adjusted R squared (R2) and standard error of the estimate (SEE) values of the models. Results: The multiple linear regression models of the mean width, depth and height of L4 yielded the highest prediction accuracies with the lowest prediction errors (for the entire sample, R2 = 0.621 and SEE = 5.635 cm; for men, R2 = 0.306 and SEE = 5.125 cm; for women, R2 = 0.367 and SEE = 4.640 cm). Conclusions: When conventional methods for estimating stature are not applicable, the lumbar vertebrae may be utilized for this purpose. Relatively accurate stature estimates can be given on the basis of only L4 dimensions

Body mass estimation from dimensions of the fourth lumbar vertebra in middle-aged Finns

Abstract Although body mass is not a stable trait over the lifespan, information regarding body size assists the forensic identification of unknown individuals. In this study, we aimed to study the potential of using the fourth lumbar vertebra (L4) for body mass estimation among contemporary Finns. Our sample comprised 1158 individuals from the Northern Finland Birth Cohort 1966 who had undergone measurements of body mass at age 31 and 46 and lumbar magnetic resonance imaging (MRI) at age 46. MRI scans were used to measure the maximum and minimum widths, depths, and heights of the L4 body. Their means and sum were calculated together with vertebral cross-sectional area (CSA) and volume. Ordinary least squares (OLS) and reduced major axis (RMA) regression was used to produce equations for body mass among the full sample (n = 1158) and among normal-weight individuals (n = 420). In our data, body mass was associated with all the L4 size parameters (R = 0.093–0.582, p ≤ 0.019 among the full sample; R = 0.243–0.696, p ≤ 0.002 among the normal-weight sample). RMA regression models seemed to fit the data better than OLS, with vertebral CSA having the highest predictive value in body mass estimation. In the full sample, the lowest standard errors were 6.1% (95% prediction interval ±9.6 kg) and 7.1% (±9.1 kg) among men and women, respectively. In the normal-weight sample, the lowest errors were 4.9% (±6.9 kg) and 4.7% (±5.7 kg) among men and women, respectively. Our results indicate that L4 dimensions are potentially useful in body mass estimation, especially in cases with only the axial skeleton available

Temporal trends in vertebral dimensions:a case study from Finland

Abstract Vertebral fractures and other back problems represent a major, increasing worldwide health problem. This has increased the need to better understand the reasons behind this phenomenon. In addition to a reduction in bone mineral density and overall size of the vertebral body, research has indicated a possible association between the shape of the endplate and spinal disorders. As one previous study has shown changes in vertebral body dimensions between contemporary people and their medieval counterparts, we wanted to examine the potential temporal trends in vertebral size and dimensions in Finnish samples of archaeological and contemporary individuals. To conduct this study, we utilized three archaeological populations from the 16th–19th century and clinical materials from two population-based Finnish birth cohorts. As the average height of people has increased greatly since the first time period, we also height-adjusted the dimensions to provide a clearer picture of the dimensional changes that have occurred in the later temporal group. Our results were in agreement with those of the earlier study. The archaeological samples had a larger vertebral size than the contemporary population when height was adjusted for. Vertebral mediolateral width in particular had decreased, and the shape of the vertebral body had changed