Researchers at the Leibniz Institute on Aging - Fritz Lipmann Institute (FLI) in Jena announced on Apr. 1 the development of AEGIS, a free software tool that allows scientists to simulate evolution and investigate how lifespan and aging evolve under different ecological pressures and genetic constraints. The new platform is described in a study published in PLoS Computational Biology.
The diversity of aging patterns across species has long puzzled biologists, with some organisms living only weeks while others survive for centuries. Understanding what evolutionary forces drive these differences remains one of biology's central questions.
AEGIS (Aging of Evolving Genomes In Silico) was developed by researchers in the Valenzano laboratory at FLI as an individual-based modeling framework. It simulates populations where each virtual individual carries a heritable genome influencing age-specific survival and reproduction probabilities. Users can adjust parameters such as extrinsic mortality factors, reproduction modes, generation overlap, mutation rates, and more. The tool includes a graphical interface, web server access for those who prefer not to install it locally, built-in visualization features, and full documentation.
"AEGIS is designed to run in silico experiments, where researchers allow virtual populations of organisms, but also cells, to evolve genetically under different selective pressures and environmental and niche constraints," said Prof. Dario Riccardo Valenzano, Scientific Director at FLI.
The publication demonstrates that when individuals replicate with heritable gene modules affecting survival and reproduction at specific ages—without any imposed equations or dedicated aging programs—aging emerges naturally after sexual maturation. "AEGIS shows that with a few simple ingredients — replication, mutation, and evolvable gene modules affecting survival and reproduction at discrete ages — aging emerges inevitably after sexual maturation," said Valenzano.
One demonstration using AEGIS replicates Rose's classic 1984 fruit fly experiment: flies selected for late-life reproduction evolved longer lifespans over generations; however, this advantage diminished when exposed to simulated environments with high external hazards—a result consistent with theoretical predictions about senescence under natural risks.
Beyond reproducing known results from evolutionary biology studies like Rose’s experiment on Drosophila melanogaster fruit flies or Hamilton’s mathematical predictions from 1966 regarding hereditary variation under age-structured selection pressure—the tool provides outputs supporting population genetics analyses such as site frequency spectra or allele dynamics without imposing model assumptions about mortality plateaus or survivorship curves.
"With AEGIS you can run experiments on your laptop and accumulate large amounts of data," said Valenzano. "We are thrilled AEGIS is finally out... I look forward to seeing this tool adopted by an increasing number of researchers interested in how evolution molds lifespan and aging." The project began with conceptual contributions from former intern Arian Šajina before being advanced by Will Bradshaw during his PhD work; Martin Bagic completed the project through analysis validation writing efforts leading up its publication.
