Articular modifications as an indicator of activity in archaeology

Less research has been undertaken on femoral modifications than tibial and talus squatting facets. This may be due to the difficulty in identifying femoral modifications and the limited amount of research which exists on the subject. Regardless, Kovacik et al. (2004) examined Charles’ facets, Martin’s facets and osteochondritic and tibial imprints in a

Byzantine population thought to have undertaken genuflexion daily as part of religious observance. All four traits were found in over 75% of individuals, with Charle’s

facet present in 94% of individuals, Martin’s facet in 77%, osteochondritic imprints in 79%

and tibial imprints in 87.5%. Kovacik et al. (2004) compared these results to known squatting Nigerian populations and found higher prevalence of tibial imprints but lower prevalence of Martin’s facets. The number of osteochondritic imprints was comparable to Nigerians. Kovacik et al. (2004) point out that both populations had a higher prevalence than most other Homo sapien groups. The authors advocated that the force of getting up and down during many multiple genuflexions would create changes in the articular cartilage of the knee. The high frequency of Charles and Martin’s facets in non-squatting populations makes the choice of these modifications for examination confusing as they are not yet confidently linked with squatting or kneeling.

The presence of tibial and talar squatting facets has been taken as evidence for a number of activities and postures adopted in the past. Ari et al. (2003) examined the prevalence of tibial squatting facets in a 13^th-century Byzantine sample. Frequency comparison between modern Europeans, Australians and Indians demonstrated that the Byzantine sample had a higher rate than contemporaneous Europeans, but less than the other two samples. The authors argued, through the use of comparative data, that the appearance of squatting facets is subject to different factors in different populations, yet did not speculate as to what these differences might be. They also added that pes valgus deformity may induce squatting facets, but failed to say how this conclusion was derived from the study presented; no data regarding of the frequency of the deformity is given. The authors failed to state whether their methods matched those used on the comparative material, and hence the inter-population comparison may be affected.

The analysis of single non-pathological modifications provides little information about specific past activities, as multiple activities can be carried out in a squatting position.

Therefore most studies use multiple modifications and additional types of evidence to inform about past lifestyles.

As outlined earlier, Boulle (2001b) examined the presence of lateral squatting facets and tibial retroversion in a diachronic (1^st – 20^th centuries AD) analysis of French and American archaeological series. A decrease in frequency of the lateral squatting facet over time reinforced the idea that a change in social attitudes and the production of chairs meant that squatting as a posture declined in the Middle Ages to modern times.

Similarly to Boulle (2001b), Dlamini and Morris (2005) examined the prevalence of tibial squatting facets of four South African groups and the relationship to historic information on furniture and ethnicity; Later Stone Age (LSA) foragers, Iron Age (IA) farmers, free black slaves (18^th century) and modern South Africans. Only LSA foragers and IA farmers had evidence for a wide adoption of the squatting posture. Only a single free slave had a squatting facet in the modern material. Like Boulle (2001b), the authors suggested that changing use of furniture and house space caused a decrease in the use of the squatting position over time. In addition, cultural and individual preference in posture adoption may influence squatting-facet prevalence in past peoples.

Ubelaker (1979) described bony alterations to the metatarsals, which he believed were caused by prolonged hyperdorsiflexion of the metatarsophalangeal joint adopted while in a kneeling position. The prevalence of metatarsal alterations correlated positively with femoral condyle flattening. No specific activity was proffered as an explanation for the modifications beyond that of a prolonged kneeling for rest or adoption of the posture for work activities.

In one of the only research projects using multiple indicators, Ullinger et al. (2004), Ullinger et al. (2005) and Kovacik et al. (2004) assessed femora, tibiae, tali, metatarsals and phalanges in two groups from medieval Jerusalem to look for evidence of genuflexion and toe hyperdorsiflexion during prayer. The authors found that there was little difference in the prevalence of squatting facets between the monastic (St Stevens) and lay community (Umm el-Jimal), suggesting similar levels of hyperdorsiflexion in both populations.

Although the frequency of metatarsal extensions was higher in the monastic group, it failed to reach a level of statistical significance. When other factors, including eburnation,

osteophytic growth and surface porosity were considered, the monastic group appeared to have placed greater strain on their joints, thus providing evidence for more prolonged kneeling in the monks, and possibly prayer (Ullinger et al. 2004, 2005). The average age at death however was not fully considered by the authors, as this could not be ascertained for the lay group. It may have played a role in the higher level of osteoarthritis in the monastic group and makes this result a little unsound.

Molleson (1989) also observed the metatarsal extensions in some individuals from Abu Hureyra, Syria but, in addition, recorded wedging of the proximal superior surface of the proximal phalanges two to four, as well as the ankle modifications. The author deduced from the shape and size of the querns that the body was moved backwards and forwards by pushing from hyperdorsiflexed toes. Molleson (1989) believed this to be the cause of the skeletal changes at Abu Hureyra. Other evidence taken from musculoskeletal stress markers included well developed deltoid and radial tuberosity attachments. These were attributed to prolonged use of the biceps muscles occurring through pushing the saddle quern backwards and forwards over the grain.

Lai and Lovell (1992) have also used metatarsal modifications as an indicator of prolonged kneeling. Hyperdorsiflexion of the metatarsophalangeal joint while canoeing up river has been suggested as the cause as it was an ethnographically known occupation for the fur trade post men from which their sample derived.