Dental biorhythm is associated with adolescent weight gain

Abstract

Background Evidence of a long-period biological rhythm present in mammalian hard tissue relates to species average body mass. Studies have just begun to investigate the role of this biorhythm in human physiology. Methods The biorhythm is calculated from naturally exfoliated primary molars for 61 adolescents. We determine if the timing relates to longitudinal measures of their weight, height, lower leg length and body mass collected over 14 months between September 2019 to October 2020. We use univariate and multivariate statistical analyses to isolate and identify relationships with the biorhythm. Results Participants with a faster biorhythm typically weigh less each month and gain significantly less weight and mass over 14-months, relative to those with a slower biorhythm. The biorhythm relates to sex differences in weight gain. Conclusions We identify a previously unknown factor that associates with the rapid change in body size that accompanies human adolescence. Our findings provide a basis from which to explore novel relationships between the biorhythm and weight-related health risks.

Human‐like enamel growth in Homo naledi

“…Accumulating evidence indicates that RP reflects an underlying biological cycle that acts upon the mammalian hypothalamus. It is hypothesized that the cycle regulates cell growth when compared between mammalian species (Bromage et al, 2009), and it has been observed that RP relates to body mass and maturation rate within human adolescents (Mahoney et al, 2022). These findings have been important for developing ideas about the evolution and pace of primate life history (Bromage et al, 2012), whereby the higher mean RP of recent humans relative to other hominins may relate to a unique life history profile (e.g., Hogg et al, 2020).…”

“…Teeth were sectioned through the midline of the canines and the distal cusps of the molar passing through the dentin horn. Standard procedures (see Mahoney et al, 2022) were employed but with one modification to accommodate subsequent chemical and molecular analyses. Specifically, teeth were embedded in crystal bond (Agar Scientific) before additional embedding in resin (Buehler EpoxiCure), so that the sectioned portions of each tooth could be removed from the resin.…”

Longitudinal changes in juvenile and adolescent body mass indices before, during, and after the COVID‐19 lockdown in New Zealand

“…We do not offer an hypothesis but suggest that a tentative set of empirically supported relationships may offer clues for future investigations. First, biorhythm variation identified in deciduous teeth (the number of daily cross‐striations between striae of Retzius) from a sub‐sample of these Dunedin school children is associated with their weight gain over the full period of the study, but not in a linear manner (Mahoney et al 2022). A portion of the variation in this expressed biorhythm might reflect physiology that is more sensitive to changing conditions of energy availability.…”

“…Students were recruited in their last year of primary school and followed as they transferred to intermediate schools in the Dunedin area. The participants were part of the Biorhythm of Childhood Growth project (Mahoney et al 2022). The project is an ongoing prospective cohort study that investigates childhood development in middle‐income children from Southern New Zealand.…”