Development, the process that gives rise to an adult organism also causes aging, according to Harvard Medical School researchers Joao Pedro de Magalhaes and George Church.
In “Genomes Optimize Reproduction: Aging as a Consequence of the Developmental Program,” appearing in the August issue of the journal Physiology, Joao Pedro de Magalhaes and George Church assert that the aging process is driven by the same genetic processes that drive development.
The idea that development is linked to aging has been frowned upon by scientists for decades, but new evidence demonstrates the two are not only linked but that aging and development are regulated by the same genetic mechanisms. “We now know of several animals that can delay development and as a result delay aging as well,” said lead author de Magalhaes. “Even in mammals there is growing evidence that aging is a consequence of developmental mechanisms. For instance, the pace of development influences the pace of aging, suggesting that the timing of developmental mechanisms determines the timing of aging in mammals.” Hence, the researchers argue that the same genes that regulate the way children grow and develop will later be responsible for their degeneration.
While the same genes drive development and aging, the researchers do not consider that aging is an intentional product of evolution like development. “I don’t think aging is under strong selection,” de Magalhaes said. “What happens, at least in higher organisms like mammals, is that evolution is not about selecting for long life. Evolution is about optimizing developmental mechanisms for reproduction. Once an organism has passed its genes to the next generation evolution gives up on it and the same genes responsible for the growth and maturation of that organism will inadvertently end up killing it. Examples include cell proliferation genes that are crucial in embryonic development but at older ages become harmful and can cause cancer and other age-related diseases.”
One optimistic aspect of this new work is that scientists already know a number of genes regulating development and aging. “Some hormones like growth hormone and genes involved in insulin-like signaling appear to do just that: they regulate growth and development early in life and later contribute to aging. Still,” de Magalhaes warned, “there is a lot of work to be done before we know all the genes involved. Development and aging are so complex that it will be some time before we fully understand them.”
