In 1958, Theodosius Dobzhansky published an essay discussing the relation between homoeostasis and senility, and how natural selection affects both1. On it, Dobzhansky reflected on the concept of homoeostasis, defined by Walter Cannon some years before as the wisdom of the body2, or the ability to, through controlled changes in the organism, adapt to changes in the eviroment, provided that they are within the “normal” changes the organism had evolved to withstand. He also linked this concept with ageing, by defining the later as the reduction of this adaptability or plasticity agains “normal” enviromental changes. Specifically, he proposed that the homeostatic buffering against enviromental shocks is weakened during the postreproductive phase.
In his work The Causes of Evolution, Haldane considered this topic without any clear conclusion. To him, natural selection may either favor or hinder the prolongation of life during the postreproductive phase3. To Dobzhansky, the fact that homoeostatic mechanisms tend to deteriorate during the autumm of life, while the same function most efficiently during youth and maturity, is indication of how these are fashioned by natural selection. Of course, we now understand in much more detail how far the link between homoeostasis and ageing goes, knowing specific cell paths, cellular systems, and other homoeostasis mechanisms for which heritable malfuction (or even slightly under-optimal function) is a cause for a hastened ageing process.
After decades of tentative work on these determinants of ageing, in 2013, a seminal work finally established a precise framework to study how genetic determinants and their interaction with the environment regulates this process4. The framework is based on nine hallmarks of ageing.
- Dobzhansky, T. (1958). Genetics of Homeostasis and Senility. Annals of the New York Academy of Sciences, 71(6):1234–1242.
- Cannon, W. B. (1934). The wisdom of the Body. Nature, 133:82.
- Haldane, J. B. S. (1933). Causes of evolution. Longmans Green & Co.
- López-Otín, C., et al. (2013). The hallmarks of aging. Cell, 153(6):1194.