A Pain in the Neck: Vertebral steoarthritis and Related Activity Patterns in Early Bronze Age Jordan

L.A. Gregoricka and J.M. UllingerDepartment of Anthropology, The Ohio State University

Introduction

Background

Materials and Methods

Results and Discussion

Conclusion

Acknowledgements

This study hypothesized that an increase in sedentism at the Early Bronze Age site of Bab edh-Dhra’ led to decreased mobility and changing workload demands. This was tested by evaluating changes in spinal degenerative joint disease frequencies over time. Specifically, cervical vertebrae were examined for changes such as vertebral body osteophytic growth, Schmorl's nodes, and eburnation and lipping on the apophyseal joint surfaces.

Adult cervical vertebrae were examined from EB IA (n=139) and EB II-III (n=555). The commingled nature of these remains precluded the identification of individual vertebral sequences. Vertebrae were scored for presence and severity of osteoarthritic lipping, porosity, eburnation, and osteophytosis based on standards outlined by Buikstra and Ubelaker (1994). The rank of ‘present’ includes moderate to severe scores, while ‘absent’ refers to no or barely discernable pathological activity. Schmorl’s nodes were scored based only on presence or absence.

This research was supported by the NSF-REU (SES 0649088) Summer Research in Biocultural Anthropology at the University of Notre Dame, Notre Dame’s Institute for Scholarship in the Liberal Arts, a Smithsonian Institution Pre-doctoral Fellowship, and a Sigma Xi Grant-in-Aid of Research. Thanks to Dr. Susan Guise Sheridan for use of the

collection and laboratory as well as for her support and encouragement.

Located on the Dead Sea Plain in modern-day Jordan, the Early Bronze Age (EBA - 3150-2150 BCE) site of Bab edh-Dhra’ provides evidence of a turning point in the southern Levant in which agricultural intensification and urbanization were taking place (Esse 1989; Mazar 1990). The continuous occupation of Bab edh-Dhra’ throughout the EBA as represented by skeletons from EB I-III allows for a more comprehensive reconstruction of changing subsistence strategies and the resultant modifications in activity patterns.

Degenerative joint disease (DJD) is an age-progressive articular disorder characterized by osteophytic growth on amphiarthrodial joint margins and porosity and/or erosion on apophyseal joint surfaces due to the deterioration of articular cartilage and the resultant reaction of subchondral bone (Lovell 1994). The study of DJD allows for an evaluation of a population’s mechanical loading history as well as a reconstruction of activity patterns in the past. For example, cervical vertebral degeneration may be attributable to the practice of consistently carrying loads on the head, an activity that generates substantial axial strain. Moreover, DJD provides an important glimpse into past societal organization, enabling bioarchaeologists to differentiate between changing activity patterns with the intensification of agricultural practices (e.g., Bridges 1989; Larsen 1995; Cohen and Crane-Kramer 2007). A similar pattern shift has been noted between rural and urban groups (e.g., Danforth 1999; Slaus 2008). The continuous occupation of Bab edh-Dhra’ throughout the EBA thus presented a unique opportunity to examine the complex relationship among subsistence strategies, settlement organization, and pathological bony responses.

Extensive research into the transition from pre-agricultural to agricultural lifestyles has illustrated changes in health and daily activities in response to shifting subsistence patterns (e.g., Angel 1984; Bridges 1989; Larsen 1995; Eshed et al. 2004). A similar pattern shift has been noted between rural and urban groups (e.g., Danforth 1999; Slaus 2008). Particularly with regards to degenerative joint disease, changes in physical activity can result in both an increase and a decrease in the frequency of location-specific lesions. For example, joint deterioration as a result of modifications in body movement involving the thoracic region, shoulders, and elbows increased after the adoption of agriculture, while lower arm and upper leg degeneration decreased (Larsen 1995). Cervical vertebral degenerative joint disease may be attributable to the practice of consistently carrying loads on the head, an activity that generates substantial axial strain. As the most mobile region of the spine, cervical vertebrae are particularly vulnerable to mechanical stress on the head (Mahbub et al. 2006).

This study concluded that an increasingly sedentary lifestyle at Bab edh-Dhra’ led to a more strenuous workload characterized by increased axial loading due to heavier burdens carried over shorter distances, but a lack of change in facet joint degeneration suggests that no changes in neck mobility took place.

Osteophyte frequency increased significantly from EB IA to EB II-III in all cervical vertebrae except C7, which had an inadequate sample size (Table 1). Schmorl’s node frequencies were low, with no differences between time periods (Table 2). The incidence of eburnation did not change significantly and was also rare in both EB IA and II-III (Table 3). No significant differences were found in regards to lipping on the apophyseal joints (Table 4).

Clinical studies of carrying loads on the head illustrate pathological modifications on the cervical spine associated with heavy loading (e.g., Joosab et al. 1994). Two identified techniques of load-carrying on the head include (a) carrying lighter loads over longer distances or (b) carrying heavier loads over shorter distances (Echarri and Forriol 2005). Individuals traveling shorter distances while supporting heavier loads display a higher incidence of cervical degeneration and injured intervertebral disks as compared to those transporting lighter burdens across a longer distance. This fits with what is known regarding mechanical loading in vertebrae, namely that apophyseal joints are largely responsible for movement while intervertebral joints limit mobility but provide much-needed support (Weber et al. 2003).

osteophytes but no change in the incidence of osteoarthritic lipping. More mobile populations may have carried lighter loads on the head in order to more efficiently cope with these burdens over greater distances. Alternatively, year-round sedentism may have entailed less overall movement across the landscape, resulting in shorter distances required to reach the settlement; in conjunction with higher yields generated by intensified food production, a heavy load/short distance pattern may have emerged. Subsequently, increasingly severe cervical osteophytosis without apophyseal joint change from the EB IA to II-III may have signaled a shift in transportation techniques from the more mobile individuals of the EB IA carrying lighter loads over longer distances to the more sedentary agriculturalists of the EB II-III carrying heavier loads on the head over shorter distances. This corresponded to increasing stress on intervertebral joints and hence elevated rates of osteophytosis while accounting for a lack of change in apophyseal lipping, as significant changes in neck movement did not occur.

n # % n # %

C1-7 Superior* 114 0 0 380 3 0.8C1-7 Inferior 122 0 0 523 3 0.6

EB IA EB II-IIILocation

n # % n # %

C1-7 Superior* Right 139 0 0 540 2 0.4C1-7 Superior Left 135 0 0 521 0 0C1-7 Inferior Right 133 0 0 551 3 0.5C1-7 Inferior Left 133 0 0 555 2 0.4

EB IA EB II-IIILocation Side

FIGURE 1: Degree of vertebral body osteophytosis 0-3

BD 1488.82 BD 1275.1089 BD 1448.1001BD 1134.3004

n % EB IA EB II-III n % EB IA EB II-III

Harappa* Pakistan 3000-2000 BC 108 36.0 <0.01 <0.01 186 18.0 0.01 <0.01 Lovell 1994Tomb II, al-Sufah UAE 2400-2300 BC 117 0 1 <0.01 98 3.0 0.08 0.25 Blau 2001

Mowaihat UAE 2300-2100 BC 136 5.0 0.02 <0.01 101 2.0 0.03 0.11 Blau 2001Bahriyah Oasis Egypt 332-30 BC 143 19.6 <0.01 0.06 159 38.4 <0.01 <0.01 Hussien 2009Khan el-Ahmar Judean Desert 428-1250 AD 82 6.1 0.01 0.03 - - - - Hershkovitz et al 1995Mamilla Cave Jerusalem ca. 614 AD 39 5.5 0.06 0.09 70 9.9 0.43 0.11 Nagar et al 1999

Bab edh-Dhra' EBIA Jordan 3150-3050 BC 120 0 - <0.01 133 8.3 - 0.15 present studyBab edh-Dhra' EBII-III Jordan 2900-2300 BC 486 13.8 <0.01 - 539 5.4 0.15 - present study

ReferenceDateRegionCollectionOsteophytes Fisher's Exact p-value Osteoarthritis Fisher's Exact p-value

TABLE 2: Occurrence of Schmorl’s nodes in cervical vertebrae.

n # % n # %

C1-7 Superior 112 0 0 358 55 15.4C1-7 Inferior 120 0 0 486 67 13.8C2 Inferior 23 0 0 129 27 20.9C3-6 Superior 71 0 0 345 53 15.4C3-6 Inferior 69 0 0 343 40 11.7C7 Superior 19 0 0 13 2 15.4C7 Inferior 20 0 0 14 0 0

EB IA EB II-IIILocation

TABLE 1: Occurrence of osteophytes in cervical vertebrae.

Significant differences (p<0.05) are indicated with bold text.

*None of the results are significant (p<0.05).

TABLE 3: Occurrence of eburnation in cervical vertebrae.

*None of the results are significant (p<0.05).

The transition to a more sedentary way of life at Bab edh-Dhra’ was accompanied by an increased frequency of osteophytes but no change in the incidence of osteoarthritic lipping. More mobile populations may have carried lighter loads on the head in order to more efficiently cope with these burdens over greater distances. The transition to a more sedentary way of life at Bab edh-Dhra’ was accompanied by an increased frequency of

n # % n # %

C 1-7 Superior* Right 137 9 6.6 543 29 5.3C 1-7 Superior Left 135 12 8.9 514 31 6.0C 1-7 Inferior Right 132 5 3.8 547 19 3.5C 1-7 Inferior Left 133 11 8.3 539 29 5.4

EB IA EB II-IIILocation Side

TABLE 4: Occurrence of lipping in cervical vertebrae.

*None of the results are significant (p<0.05).

TABLE 5: Comparative data of degenerative changes in cervical vertebrae.

Period Date Subsistence Mortuary Practices Settlement

EB IA 3150-3050 BCEHorticulture/ Agriculture

Shaft tombsNo significant archaeological

remains

EB IB 3050-2900 BCE Agriculture Round charnel houses First permanent settlement

EB II-III 2900-2300 BCEIntensive

agriculture with orchards

Large, rectangular charnel houses

Increasingly sedentary; fortification and large wall; irrigation system

Periods of occupation at Bab edh-Dhra’.