The struggle to stop aging (without starving) advances another step
Friday, April 18th, 2008Talking about slowing down or stopping aging seems like talking about magic, something unnatural, the substance of a movie, a sign of excessive fear of the inevitable, a foolish desire to avoid a promising afterlife, an attempt to sell something to the gullible, or just a short cut to losing all credibility. Aging is baked into our understanding of the world, into the structure of families, the unfolding of human history, the forms of our storytelling, and into how people decide upon their beliefs.
Yet because aging has been inevitable does not mean it will continue to be. David Hume once pointed out, “No amount of observations of white swans can allow the inference that all swans are white, but the observation of a single black swan is sufficient to refute that conclusion.” Human history has been filled with the white swan of aging, and it makes us doubt the black swan of a method to halt aging could actually exist.
There are reasons to believe that aging at the rates humans experience isn’t inevitable and could be modified. The first reason is that different species age at different rates. Charles Darwin explained that species evolved from common ancestors, through the pressures of selection and time. The rate of human aging may therefore be an evolutionary accident or due to selection pressures humanity could use its creativity to escape.
A second reason is that some human beings have diseases which cause them to appear to age significantly faster than normal (see wikipedia article on progeria). If the process of aging can be modified by a genetic abnormality in one direction, it could possibly be modified in the other direction.
A third reason is that aging has already been slowed down significantly in many creatures by severe caloric restriction. This appears to effect metabolism, which then effects the rate of aging. While caloric restriction has worked in even lower order mammals, large scale human studies have yet to be completed. Even if caloric restriction was shown to work in people it requires significant discipline while impacting lifestyle significantly.
These reasons provide potential means for exploring the processes of aging. A great deal of fruitful research has been done on aging in yeast cells. It is the current scientific understanding that inside a yeast cell a reduction in caloric intake causes a reduction in three enzymes (TOR, Sch9, and PKA) that are part of the metabolism process. Reductions in TOR in particular decreases the rate by which a cell creates new proteins and slows aging.
Now, in the April 18, 2008 issue of the journal Cell (see link), a team of researchers led by Brian Kennedy and Matt Kaeberlein have published research linking ribosomes, the protein-making factories in living cells, and Gcn4, a specialized protein that aids in the expression of genetic information, to the pathways related to dietary response and aging.
By studying different strains of yeast cells they found that mutations in the large subunit of ribosomes sometimes led to increased lifespan. They also tested diazaborine, a drug which interferes with the large subunit of ribosomes, and found that treated cells lived 50 percent longer than untreated cells. They also found that longer lived yeast strains with mutations in the large subunit of the ribosome produce an extraordinary amount of Gcn4, a specialized protein which helps transfer genetic information during cell growth. They then tried preventing the increase of Gcn4 to see if it would effect life span, and it did in fact lead to shorter life spans. The researchers have thus found three different ways to effect aging in yeast cells. (This is not the only research approach being followed; see my prior post)
The path from such research in yeast cells to a treatment for human beings will likely be a very long one. While it is possible that a means to short circuit the aging process without significant side effects may be discovered (as was discovered for creating a twin of a sheep; see my prior post), it is far more likely to take decades, or a century.
Yet there could come a time when denying someone anti aging treatments is considered cruel and unusual. Perhaps some people born today will live to see that time. If so, they may be the only people living to have once thought of aging as natural and inevitable. They may have great difficulty in convincing anyone that aging was anything other than a disease, waiting for a cure.
