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5 An Overview of the Biology of Aging: A Human Perspective

George M. Martin, Caleb E. Finch


The power of genetic analysis in model organisms, notably yeast, worms, flies, and mice, has yielded enormous understanding of the genetic modulations of life span, as clearly demonstrated in the pages of this volume. We now have at hand the first demonstrable “public” mechanism for life span modulation—variations in the function of the insulin/insulin-like growth factor-1 (IGF-1) signaling pathway, a signaling transduction network that evolved in nature to enhance reproductive fitness in the context of metabolic trade-offs (Partridge and Gems 2002). These lab creations, however long-lived they may be, would be unlikely to survive as long in the real environments wherein the wild types had evolved (Walker et al. 2000).

Recognizing the divide between the lab and the Darwinian world should not deter us from further digging in the gold mine of model systems and looking for yet other gero-rich veins. We anticipate that other insect species with multifarious diapauses and life history alternates in nature (Brown and Hodek 1983; Finch 1990) might be “tweaked” by investigators to learn their secrets of slowing and accelerating biological time through epigenetically determined alternative developmental phenotypes. Enticing prospects are offered by the social insects, with many examples of life history alternates, best known at present in the 100-fold difference in life spans of worker bees and queen bees. This is becoming an especially attractive area of research, given the growing genome database of social insects (Birney et al. 2006) and the emergence of sociogenomics (Robinson et al. 2005).

Our tidy yeast and...

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