Before puberty, the human body actively maintains the function of ribosomal DNA (rDNA)—a section of the genome essential for cell survival. However, in adulthood, its efficiency declines, triggering molecular mechanisms of aging. This conclusion was reached by researchers from Germany, and their findings were published in Aging-US.

The scientists analyzed blood samples from 280 individuals ranging in age from birth to 18 years. They assessed two key indicators: the number of rDNA copies and their level of methylation—a chemical tag that “switches off” gene activity. It turned out that in children and adolescents, the number of active (unmethylated) copies does not decrease but rather slightly increases. This means that at a young age, cells maintain rDNA function in a “youthful” state.

In adults, however, the opposite process occurs: with age, the number of active copies decreases, while methylation levels rise. According to the researchers, such changes serve as a reliable biomarker of cellular aging.

“Our data show that in the tissues of young people, the active state of rDNA is maintained at the molecular level. This may be part of a natural mechanism for preserving cellular youth,” the authors of the study noted.

The research also showed that changes in rDNA are not associated with developmental delays in children and therefore are not the cause of early pathologies.

The results support the idea that biological aging is not a continuous process but rather a mechanism that activates once the body becomes ready for reproduction. The researchers note that this discovery may change the approach to combating aging. Instead of treating its consequences, scientists suggest focusing on strengthening the mechanisms that, in youth, protect cells from age-related changes.