Why do organisms age: Beyond energy trade-offs
Dr. Alexei Maklakov
Reader in Evolutionary Biology, University of East Anglia (UK)
Despite tremendous progress in recent years, our understanding of the evolution of ageing is still incomplete. The long-standing paradigm maintains that ageing evolves because of competing energy demands of reproduction and somatic maintenance leading to slow accumulation of unrepaired cellular damage with age. This paradigm has been increasingly challenged as studies in different organisms managed to uncouple reduced reproduction and increased longevity, thereby questioning the centrality of energy trade-offs in ageing. Emerging theory proposes that ageing is caused by biological processes that are optimised for early-life function but become harmful when continue to run-on unabated in late-life. This theory builds on the realisation that early-life regulation of gene expression can break down in late-life because natural selection is too weak to optimise it. Empirical evidence suggests that suboptimal gene expression in adulthood can indeed result in excessive biosynthesis and reduced cellular maintenance leading to organismal senescence. I will discuss this in the context of the evolutionary theory of ageing, and show recent experimental data testing these ideas in Caenorhabditis nematodes.