Lower limb entheseal morphology in the Neandertal Krapina population (Croatia, 130 000 BP)

Entheseal variation and locomotor behavior during growth

Entheses are acknowledged as skeletal markers capable of revealing several biological and behavioral aspects of past individuals and populations. However, entheseal changes (ECs) of juvenile individuals have not yet been studied with a systematic approach. This contribution aims at investigating the morphological changes occurring at the femoral insertion of the gluteus maximus and tibial origin of the soleus muscles to highlight a potential link between the morphological features of those entheses and skeletal maturity in relation to sex, age, and locomotor developmental patterns. The sample consisted of 119 skeletons (age-at-death: 0-30 years) belonging to the Documented Human Skeletal Collection of the Certosa Cemetery (Bologna, Italy). The entheseal variation during the last stages of skeletal maturation in young adults was assessed using existing recording standards. A recording protocol for each enthesis was developed for immature individuals to subdivide the morphological variability into discrete categories. Univariate, bivariate, and multivariate statistical analyses were performed to investigate the variation of entheseal morphologies and measurements in relation to bone metrics, degree of epiphyseal closure, sex, age, and locomotor developmental patterns. A statistically significant relationship was observed between ECs morphological patterns and age for both entheses, while sexual differences were negligible. A relationship between ECs morphological pattern and locomotor milestones emerged only for the gluteus maximus. Even though further testing is needed on other documented skeletal collections, our protocol could be usefully applied in forensic and archaeological fields and serving as important reference for evolutionary investigations.

Main morphological characteristics and sexual dimorphism of hominin adult femora from the Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain)

The excellent fossil record from Sima de los Huesos (SH) includes three well-known complete adult femora and several partial specimens that have not yet been published in detail. This fossil record provides an opportunity to analyze the morphology of European pre-Neandertal adult femur and its variation with different evolution patterns. Currently, there are a minimum of five adult individuals (males or females). In this study, we compiled previously published basic anatomical and biometric characteristics of SH adult femora, emphasizing the most relevant features compared to other recent and fossil hominins. The SH femora exhibited a primitive morphological pattern common to all non-Homo sapiens femora, as well as most of the Neandertal traits. Therefore, the complete Upper Pleistocene Neandertal pattern was well-established in Middle Pleistocene ancestors long before the proper Neandertals appeared. Additionally, we highlight that the SH and Neandertal femora share some morphological traits and proportions with modern humans that hold sexual significance in our species, regardless of size. Keeping this in mind, we discussed the sex determination of the complete SH specimens and re-evaluated sex allocation in two of them.

Estimation of adult age-at-death from entheseal robusticity: A test using an identified Italian skeletal collection

OBJECTIVES

The present study tests the effectiveness of entheseal robusticity (ER) as a potential predictor of adult age-at-death by applying multiple regression models to a large contemporary identified skeletal sample.

MATERIALS AND METHODS

ER was recorded for 23 bilateral postcranial entheses on 481 adult individuals (271 females and 210 males) from the Frassetto identified skeletal collection of Sassari (Italy), following the method of Mariotti et al. 2007. ER scores were used as predictors in multiple regression analyses with age as the dependent variable; the performance of the resulting models was tested through standard error of estimate, the correlation coefficient between predicted and documented age, and the percentage of correctly classified individuals.

RESULTS

ER show a higher correlation with age in females, resulting in more accurate estimates when compared with those obtained for males. Age-at-death is overestimated for male individuals under 45 years old and underestimated for older individuals. Regression models including a reduced set of ER sites result in better estimates compared with those using the complete set of variables.

DISCUSSION

Results suggest the potential usefulness of ER for the estimation of age, especially for female skeletal remains. If used with caution, ER may be a valid complement to existing methods for the reconstruction of the biological profile of skeletal remains of archaeological and forensic interest.

The study of the lower limb entheses in the Neanderthal sample from El Sidrón (Asturias, Spain): How much musculoskeletal variability did Neanderthals accumulate?

Entheses have rarely been systematically studied in the field of human evolution. However, the investigation of their morphological variability (e.g., robusticity) could provide new insight into their evolutionary significance in the European Neanderthal populations. The aim of this work is to study the entheses and joint features of the lower limbs of El Sidrón Neanderthals (Spain; 49 ka), using standardized scoring methods developed on modern samples. Paleobiology, growth, and development of both juveniles and adults from El Sidrón are studied and compared with those of Krapina Neanderthals (Croatia, 130 ka) and extant humans. The morphological patterns of the gluteus maximus and vastus intermedius entheses in El Sidrón, Krapina, and modern humans differ from one another. Both Neanderthal groups show a definite enthesis design for the gluteus maximus, with little intrapopulation variability with respect to modern humans, who are characterized by a wider range of morphological variability. The gluteus maximus enthesis in the El Sidrón sample shows the osseous features of fibrous entheses, as in modern humans, whereas the Krapina sample shows the aspects of fibrocartilaginous ones. The morphology and anatomical pattern of this enthesis has already been established during growth in all three human groups. One of two and three of five adult femurs from El Sidrón and from Krapina, respectively, show the imprint of the vastus intermedius, which is absent among juveniles from those Neanderthal samples and in modern samples. The scant intrapopulation and the high interpopulation variability in the two Neanderthal samples is likely due to a long-term history of small, isolated populations with high levels of inbreeding, who also lived in different ecological conditions. The comparison of different anatomical entheseal patterns (fibrous vs. fibrocartilaginous) in the Neanderthals and modern humans provides additional elements in the discussion of their functional and genetic origin.

A muscular imprint on the anterolateral surface of the proximal femurs of the Krapina Neandertal collection

OBJECTIVES

The purpose of this study is to report and interpret a feature on the anterolateral surface of the proximal femurs of the Krapina hominid collection that we briefly described in 2006 (Periodicum Biologorum, 108, 319-329).

MATERIALS AND METHODS

We recorded the presence or absence of the feature in all the proximal femurs of the Krapina collection (six specimens recordable) and in 622 modern human adult femurs.

RESULTS

The feature consists in a series of crests delimitating three raised or depressed areas. This feature has been found in three out of four adult Neandertal femurs observable. The two observable subadult Neandertal femurs do not show this character. None of the modern femurs displayed the feature.

CONCLUSION

We interpret this feature as a muscular imprint, probably representing the m. vastus intermedius origin and discuss a possible interpretation. We did not find any other references for such imprint in the existing literature regarding the Neandertal femurs.

Lower limb activity in the Cis-Baikal: entheseal changes among middle Holocene Siberian foragers

Lower limb entheseal changes are evaluated in order to reconstruct activity levels and more fully understand cultural and behavioral variation among the middle Holocene (ca. 9,000-3,000 years BP) foragers of Siberia's Cis-Baikal region. The four cemetery samples examined span a period of diachronic change characterized by an 800- to 1,000-year discontinuity in the use of formal cemeteries in the region. Two of the cemetery samples represent the early Neolithic Kitoi culture, dating from 8,000 to 7,000/6800 cal. BP; the other two represent the late Neolithic-early Bronze Age Isakovo-Serovo-Glazkovo (ISG) cultural complex, dating from 6,000/5,800 to 4,000 cal. BP. Findings suggest a dynamic pattern of cultural variability in the Cis-Baikal, with spatial distribution (i.e., site location within particular microregions) appearing to be just as important a factor as cultural/temporal affiliation in explaining intersample differences in entheseal morphology. In addition, intrasample comparisons reveal increasing sexual disparity with advancing age at death, emphasizing the influence of sex-related activities on lower limb entheseal changes. Finally, results from the separate fibrous and fibrocartilaginous datasets appear to be largely congruous, implying that activity patterns in the Cis-Baikal may have similar effects on the morphology of both types of entheses.