Cross-Species Analysis Reveals No Universal Programmed Aging Mechanism: Insights from Single-Cell Transcriptomics in Zebrafish, Fruit Fly, and Nematode

The question of whether aging follows a universal programmed process has been a topic of debate for a long time. Previous arguments, either supporting or refuting programmed aging, were mainly based on different evolutionary biology theories. In this study, we analysed single-cell RNA sequencing data from zebrafish, fruit fly, and nematode at various stages of development to explore gene co-expression modules across these species. We successfully identified a co-expression module related to ribosomal protein genes that is shared across the early development stages in multiple tissues of all three species. However, we did not find any cross-species shared gene co-expression modules related to aging. Further analysis of gene regulatory networks (GRNs) demonstrated that although certain aging-related genes are conserved, their regulatory mechanisms vary significantly between species. These findings suggest that aging is not governed by a conserved universal program but rather by species-specific adaptations to damage and environmental conditions.