1. Reconstruction of labour intensity in Neolithic early agriculturalists from central Poland Wiesław LORKIEWICZ Marta KUREK Agnieszka ŁĘGOCKA Joanna URBANIAK

2. Objectives The objective of this work is to compare the usefulness of markers of musculoskeletal stress markers for reconstructing the specificity and intensity of physical activity in skeletal population studies. To achieve this goal, two skeletal series were selected from the osteological collection of the Chair of Anthropology of the University of Łódź, which represent human populations that should be characterized by marked differences in terms of lifestyle and level of biomechanical loading of the skeleton. Material The material comprises two skeletal series: a Neolithic one, dated to 4600- 4300 BC (49 males and 38 females) and a modern one from the 17 th -18 th centuries AD (29 males and 22 females), representing human populations inhabiting the same settlement micro-region in Kuyavia, Central Poland. The Neolithic group comes from the early waves of settlers who had arrived from the south and started the neolithization of the North European Plain. Studies conducted to date as well as the literature on early farming populations indicate a high prevalence of stress factors that affected their biological condition. In the case of the population under study, this finding is corroborated by the low average age at death of adults (35.8 for men, 33.2 for women), short stature (161.9 and 150.9 cm for men and women, respectively (Pearson method)), diminished sexual dimorphism in terms of stature and a high incidence of cribra orbitalia, enamel hypoplasia and Harris lines. The basis of subsistence was manual cultivation of small fields with hoes as well as cattle and goat farming. The studies of the concentrations of Sr, Ca, Ba and Mg indicate a mostly plant-based diet in the Neolithic population. The modern skeletal series represents the inhabitants of a medium-sized town, and the privileged localization of the burial sites near a grand town parish church (and in some cases also the remains of valuable objects placed in the graves) suggests their higher social status. This is reflected in the much higher average age at death of adults (48.2 for men and 44.2 for women), and also much higher values of the metric traits of the skeleton and body stature (165.8 cm and 152.9 cm, respectively) A map of Poland showing the location of analysed sites

3. Methods The sex and age of individuals were determined in accordance with the generally accepted methods, taking into consideration skull and pelvis morphology as well as dental attrition, cranial suture obliteration and changes in the pubic symphyseal surface. Mechanical skeletal properties were assessed on the basis of external measures of long bone shafts of the limbs: circumference in the middle of the shaft of the clavicle, humerus, radius, ulna, femur and tibia, and the largest and smallest diameter in the middle of the shaft of these bones (except for the ulna and tibia). Furthermore, in the case of the humerus, these measurements were taken at 35% of the length of the bone from the distal end. As Stock and Shaw’s studies (2007) reveal, these measures show a strong correlation with cross- sectional geometric measures of biomechanical bone strength. For the standardization of diaphyseal robusticity measures, in accordance with the suggestion of the above-mentioned authors, the product of the length of a given bone and body mass estimated with the Ruff et al. equations (1997) was used. The sexual dimorphism of the metric traits was calculated as the difference between the arithmetic mean for men and women standardized to the arithmetic mean for men (Borgognini and Repetto 1986). Musculoskeletal patterns were studied on the basis of 11 muscle insertion sites on the upper and lower limb bones and one ligament site: the lateral border and infraglenoid tubercle of the scapula (the teres minor and triceps brachii muscles), the crest of the greater tubercle and deltoid tuberosity of the humerus (the pectoralis major and deltoideus muscles), the radial tuberosity and lateral surface of the shaft of the radius (the biceps brachii and pronator teres muscles), the brachial tuberosity of the ulna (the brachialis muscle), the gluteal tuberosity and linea aspera of the femur (the gluteus maximus, vastus and adductors muscles), the tibial tuberosity and soleal line of the tibia (the quadriceps and soleus muscles), and costoclavicular syndesmosis on the clavicle. The scoring of muscular and ligament attachments is performed on the basis of scales prepared by Myszka (2007) for an early medieval skeletal series from Poland (three-point scales that take into account only changes of the robusticity type). Some more pronounced changes (stress-induced lesions), observed in the material under study, were marked as 4. The significance of differences in metric traits was assessed with the use of t-test, and in the case of MSM traits, with the U-test and sign test.

4. Robusticity scores of the infraglenoid tubercle on the scapula (Fig.1-3) Fig.1. Grade 1Fig.2. Grade 2 Fig.3. Grade 3

5. Costal impression on the clavicle (Fig.4-6) Fig.4. Grade 1 Fig. 5. Grade 2 Fig. 6. Grade 3

6. Results The populations studied reveal marked sex-specific differences in terms of absolute values of circumferences of bone shafts of the limbs: men from the modern period series are characterized by greater values of these features, while in women differences (with the same direction) concern only the circumference of femur shafts (Tab.1). A closer analysis clearly indicates that these differences are due to the large size of male bones from the modern period series, which is in turn reflected in the significantly more pronounced sexual dimorphism in this population (Tab.2).

7. However, the standardization of shaft circumferences using bone length (that is, computing typical robusticity indices) reveals a different picture: male bones from the modern period population are only slightly more robust than those in the Neolithic series (no difference being statistically significant), while upper limb bones in Neolithic women are of stronger build (Tab.3). Further information is provided by analysis of asymmetry of the circumference of limb bone shafts: it is markedly larger in the modern population (especially in terms of the upper limbs), which is most probably functionally conditioned (Tab.4).

8. The above differences in metric traits characterizing the size and proportions (robusticity) of the bones obviously result from a number of factors, and not only differences in the type and intensity of physical activity. One of the factors that must be taken into account while comparing the populations in terms of measurements of long bone shaft circumference is the much older age at death of individuals from the modern period population. Due to periosteal bone apposition, which is probably a compensatory response to endosteal bone loss with advancing age (Larsen 1997), one would expect larger shaft circumference in older individuals. Although this phenomenon may be observed in the studied material, it is only responsible for part of the differences between the populations (it is quite difficult to assess its possible impact as both series are not very numerous). Another factor affecting the above differences is the better biological condition of the modern period population, due to e.g. a better diet (the degree of sexual dimorphism is a recognized indicator of biological condition in skeletal population research). Nevertheless, the model of differences between both populations observed above, and in particular the fact that they affect the upper and lower limbs to different degrees and that they are observed in a trait that has a strongly functional character (asymmetry), indicates a significant role of physical activity in their creation. In order to exclude yet another factor affecting bone robusticity – body mass – diaphysis circumferences and the product of the smallest and largest diaphysis diameter were standardized using the product of bone length and body mass. The results are similar to those for robusticity indices (Tab.5). Summarizing the part of the analysis based on external measures of skeletal robusticity, it may be concluded that: 1) differences in activity between both populations concerned activities involving the upper limbs; 2) in the Neolithic population women were much more burdened with work (both in comparison to the modern period population and to males from the same population); 3) the type of physical activity in the Neolithic population was characterized with a significantly smaller lateralization of upper limb loading. This model of physical activity in the Neolithic population remains in accordance with expectations in terms of the state of knowledge about life in early farming populations.

9. MSM analysis As there was no significant relationship between the degree of MSM expression and age (due to the insufficient size of the series, only the Neolithic series was studied in this respect and was divided into two age groups: 17-30 and 30-50), the influence of this factor was ignored in analysis. Generally, in a simple comparison of the mean degrees of particular MSM in both populations, out of 48 examined attachment sites 37 are more strongly pronounced in the modern period series (Tab.6). The most consistent direction of differences is observed in the lower limbs. These results probably reflect the relationship between MSM and body mass (Myszka 2007), which should affect the lower limbs to a greater degree as a consequence of their locomotive and supportive functions. The general picture of variation in both populations in terms of MSM is well illustrated by the sums of mean MSM scores computed for the shoulder girdle, arm and leg (Fig.7.). They reveal a stronger pronouncement of the studied traits in the modern period population, an in both populations – in men as compared to women. Once again one can observe the relationship between body size and greater muscle markers (e.g. Weiss 2003).

10. The results of MSM examination do not, however, reflect the main elements of variation in skeletal biomechanical loading in the populations, which was observed on the basis of metric traits. Though more statistically significant differences is also noted between female series and with respect to the humerus, they are conditioned by higher values of the MSM scores in the modern period population. Neither characteristic differences in terms of sexual dimorphism nor a clear picture of directional asymmetry (which could be interpreted as evidence of functional lateralization) were observed. Conclusions The Neolithic and modern period populations reveal marked differences in terms of external measures of diaphyseal robusticity, which most probably (among other factors) reflects different models of biomechanical loading of the skeleton conditioned by the specificity of physical activity. The variation in MSM does not correspond to the specific traits of physical activity reconstructed on the basis of metric traits. The main factor responsible for the differences in MSM in the studied populations was body size. Fig.7. Sums of the mean MSM scores computed for the shoulder girdle, arm and leg.

11. References cited 1. Stock J.T. and C. N. Shaw. 2007. Which measures of skeletal robusticity are robust? A comparison of external methods of quantifying diaphyseal strength to cross-sectional geometric properties. Am J Phys Anthrop 134(3):412-423. 2. Ruff C.B., E. Trinkaus, and T.W. Holliday.1997. Body mass and encephalization in Pleistocene Homo. Nature 387: 173-176. 3. Borgognini Tarli S.M. and E. Repetto. 1986. Methodological considerations on the study of sexual dimorphism in past human populations. Hum Evol 1: 51-66. 4. Myszka A. 2007. Reconstruction of the somatic structure of man on the basis of selected skeletal traits. Poznań UAM 5. Larsen C.S. 1997. Bioarchaeology. Interpreting behavior from the human skeleton. Cambridge Univ Press. 6. Weiss E. 2003. Understanding muscle markers: Aggregation and construct validity. Am J Phys Anthrop 121:230-240.