Age changes of musculoskeletal stress markers and their inter-period comparisons

This study examines the changes with age of 15 musculoskeletal stress markers (MSMs) in the upper and lower limb bones of modem Japanese with documented ages-at-death, on the basis of original scoring criteria corresponding to each advanced stage. The procedure investigated significant differences of mean scores among five age classes at intervals of 10 years from 20 to 69 years for each MSM, and also calculated Pearson's correlation coefficients between MSM scores and age-at-death. These examinations found that most MSMs had significant correlations with aging in both sexes. MSM data of the people from the Yoshigo shell-mound in the Jomon period (Yoshigo Jomon, c. 3000-2300 BP), the Doigahama site in the Yayoi period (Doigahama Yayoi, c. 2100-1800 BP), and modem Japanese were then compared between the 20-39 and 40-59 age categories (younger adult and older adult groups, respectively) for both sexes. Kruskal -allis tests found that many MSMs showed significant differences between periods in each age category. Mann-Whitney tests revealed that many MSMs of the prehistoric Yoshigo Jomon and Doigahama Yayoi showed few significant differences, whereas those of many modem Japanese differed significantly. Principal component analysis indicated that the results of a scatter diagram in the younger adult group were considerably different from those of the older adult group. These findings suggest that MSMs are age structured within human populations, but that differences also arise in association with intensity of activity.