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Biorhythms, deciduous enamel thickness, and primary bone growth: a test of the Havers‐Halberg Oscillation hypothesis
Author(s) -
Mahoney Patrick,
Miszkiewicz Justyna J.,
Pitfield Rosie,
Schlecht Stephen H.,
Deter Chris,
GuatelliSteinberg Debbie
Publication year - 2016
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1111/joa.12450
Subject(s) - enamel paint , deciduous , molar , deciduous teeth , dentistry , biology , anatomy , orthodontics , chemistry , medicine , botany
Across mammalian species, the periodicity with which enamel layers form (Retzius periodicity) in permanent teeth corresponds with average body mass and the pace of life history. According to the Havers–Halberg Oscillation hypothesis ( HHO ), Retzius periodicity ( RP ) is a manifestation of a biorhythm that is also expressed in lamellar bone. Potentially, these links provide a basis for investigating aspects of a species’ biology from fossilized teeth. Here, we tested intra‐specific predictions of this hypothesis on skeletal samples of human juveniles. We measured daily enamel growth increments to calculate RP in deciduous molars ( n = 25). Correlations were sought between RP , molar average and relative enamel thickness ( AET , RET ), and the average amount of primary bone growth ( n = 7) in humeri of age‐matched juveniles. Results show a previously undescribed relationship between RP and enamel thickness. Reduced major axis regression reveals RP is significantly and positively correlated with AET and RET , and scales isometrically. The direction of the correlation was opposite to HHO predictions as currently understood for human adults. Juveniles with higher RP s and thicker enamel had increased primary bone formation, which suggests a coordinating biorhythm. However, the direction of the correspondence was, again, opposite to predictions. Next, we compared RP from deciduous molars with new data for permanent molars, and with previously published values. The lowermost RP of 4 and 5 days in deciduous enamel extends below the lowermost RP of 6 days in permanent enamel. A lowered range of RP values in deciduous enamel implies that the underlying biorhythm might change with age. Our results develop the intra‐specific HHO hypothesis.