Live Young and Prosper: The Dauer Way

The global average life expectancy during the early twentieth century was 31 years; today it stands at 67.2 years. The “Big Three”: food, health and hygiene are being hailed as miracle life longevity factors; however improving overall quality of life is far more complex than simply extending it. Without actually slowing down the pace at which we age, all this proposes is potentially a greater number of years spent with age related diseases, such as Alzheimer’s. But how much do we truly understand about aging?

35 genes believed to determine lifespan have been unveiled by research at the Louisiana State University Health Centre, coding for a wide range of cellular functions they indicate aging is multifactorial. At least four physiological processes are thought to play a role in aging including metabolic control, resistance to stress, gene deregulation and gene stability. Scientists will persevere in unravelling the mystery of aging and the complexity of the process means it may be one of the hardest nuts we will ever try to crack. The very nature of aging makes it difficult to gather substantial data; long term experimentation on human beings is unfeasible due to the crippling time constraints. Nevertheless, when there is a will there is a way and this is where model organisms step in.

Caenorhabditis elegans

The nematode, Caenorhabditis elegans makes an excellent aging model organism; living 2-3 weeks, the hermaphrodites among them are able to produce around 300 genetically identical offspring, providing the advantage of allele homozygosis and its small 97 megabase genome is fully sequenced. Most importantly, the Caenorhabditis elegans shares 35% similar genes with us, that are used as candidate human longevity genes and the development stages of each somatic cell are known from zygote to adult worm. Going through the complex developmental processes of embryogenesis, morphogenesis and growth, in four stages (L1, L2, L3 and L4) there is plenty to suggest that what we learn from the Caenorhabditis elegans may be directly applicable to us. When placed in harsh conditions, the L1 and L2 larvae become dauer larvae with delayed development and dark intestines produced by storage of fat. When the harsh conditions subside they re-enter the developmental process, carrying on as normal. This may seem insignificant, however these dauer larvae live 10 times the average lifespan of a normal nematode, in human terms that means reaching the age of about 700!

A study carried out by Golden JW and Riddle DL identified pheromone, food and temperature as dauer-inducing factors. The pheromone is a measure of population density, causing dauer formation at L2 and inhibiting recovery based on pheromone dose. Lack of food causes caloric restriction, a method which has also proven to extend lifespan in rodents. The enhancement of the dauer larvae formation needs exposure to high temperature at L1 stage. Two sensory mutants defective in thermotaxis have altered sensitivity to the pheromone but the pheromone response remains temperature dependent. The ways in which the dauer respond to inducing factors was found to be age dependent, with the older larvae having a greater tendency to recover. The dauer larvae seem to able to control the pace at which that metaphorical clock ticks, no doubt the day we learn to apply this in humans will be pivotal to the very nature of science.

To date the oldest age a human being has got to is 122 years, while average lifespan has certainly increased, maximum lifespan is yet to be understood and manipulated. As technology develops, our knowledge will continue to grow and maybe soon birthday cards will go up to 700 years or more.

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Technology, Time and Ageing

The question that many polymaths, scientists, technology-enthusiasts and intellectuals have been curious about ever since educational institutions were introduced is- will the world reach the period where the length of human life can be expanded? Many individuals in the global society have wished to look younger when their facial characteristics started aging and do surgical procedures as well as use cosmetics as a feature of the extended human phenotype to fulfill their desires. Technology has extended the phenotype of man to unprecedented heights. Human technologies differ from animal technologies in their inventiveness, multiplicity and sophistication. Noted experts throughout the ages have searched for the formula to the miraculous phenomenon: “Can one turn back the clock of time?” Although time travel has been a traditional plot device in science fiction since the late 19th century and the theories of special and general relativity allow methods for forms of one-way travel into the future via time dilation, it is currently unrevealed whether the laws of physics would permit time travel into the past.

Some theories, most notably special and general relativity, propose that suitable geometries of spacetime, or specific types of motion in space, might allow time travel into the past and future if these geometries or motions are possible. In technical papers, physicists generally avoid the commonplace language of “moving” or “traveling” through time (“movement” normally refers only to an adjustment in spatial position as the time coordinate is varied), and instead discuss the potentiality of closed timelike curves, which are world lines that form closed loops in spacetime, allowing objects to return to their own past. There are known to be solutions to the equations of general relativity that describe spacetimes which contain closed timelike curves (such as Gödel spacetime), but the physical plausibility of these solutions is uncertain.

Many in the scientific community believe that backwards time travel is highly implausible. Any theory that would allow time travel would require that problems of causality be resolved. The classic example of a problem involving causality is the “grandfather paradox”: what if one were to go back in time and kill one’s own grandfather before one’s father was conceived? However, some scientists believe that paradoxes can be avoided, by appealing either to the Novikov self-consistency principle or to the notion of branching parallel universes.

Nevertheless, the theory of general relativity does suggest a scientific basis for the possibility of backwards time travel in certain unusual scenarios, although arguments from semiclassical gravity suggest that when quantum effects are incorporated into general relativity, these loopholes may be closed. These semiclassical arguments led theoretical physicists to formulate the chronology protection conjecture, suggesting that the fundamental laws of nature prevent time travel, but physicists cannot come to a definite judgment on the issue without a theory of quantum gravity to join quantum mechanics and general relativity into a completely unified theory.

Dr. Bill Andrews has spent two decades solving the molecular mechanisms of aging. His mission is to extend the human life span to 150 years or die trying. In the 1990s, as the director of molecular biology at the Bay Area biotech firm Geron, Andrews supported a team of researchers that, in alliance with a laboratory at the University of Colorado, just barely beat out the Massachusetts Institute of Technology in a furious, near-decade-long race to identify the human telomerase gene. This basic science took on the trappings of a hysterical Great Race is a testament to the biological preciousness of telomerase, an enzyme that maintains the ends of our cells’ chromosomes, called telomeres.

Telomeres get shorter each time a cell divides, and when they get too short the cell can no longer make fresh copies of itself. If humans live long enough, the tissues and organ systems that count on continued cell replication begin to falter: The skin sags, the internal organs grow slack, the immune-system response weakens such that the next chest flu could be the last. Telomerase was first discovered by Professor Elizabeth Blackburn and Molecular Biologist Carol W. Greider who were both awarded the Nobel Prize in Physiology or Medicine in 2009 for this work. Though, what if bodies could be induced to express more Telomerase? That is what Dr. Andrews intends to do in order to prolong human life which would demonstrate one of the greatest breakthroughs on planet earth.

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