- Aging & Longevity
What is Negligible Senescence
Definition of Senescence
In biological terms, senescence refers to the process of aging. It includes accumulative changes which disrupt metabolism resulting in the deterioration of the organism and eventually death. Senescence occurs at two levels:
- cellular senescence whereby normal diploid cells lose the ability to divide
- organismal senescence involves the aging of the whole organism characterised by
- the declining ability to respond to stress,
- decreased reproductive capability,
- decreased strength and mobility,
- reduced sensory acuity
- increased homeostatic imbalance,
- and increased risk of age-related diseases and associated death rate.
Immortality is a long shot, I admit. But somebody has to be first. — Bill Cosby
Definition Of Negligible Senescence
The term 'negligible senescence' was first used in the 1990s by professor Caleb Finch to describe organisms like lobsters and hydra which showed no signs of senescence as they aged. Negligible senescence refers to a lack of symptoms of aging in a few select animals. These animals:
- do not have measurable reductions in reproductive capacities with age;
- do not have measurable functional decline with age including strength and mobility;
- do not have increased death rate with age.
There is strong scientific grounds to suggest that humans of advanced ages are negligibly senescent.
Just how organisms and some humans that exhibit negilgible senescence accomplish the feat of staying 'young' forever is a hot topic for longevity scientists. If the secret to their longevity and anti-aging could be discovered it could provide a stepping stone for research into extending human longevity by technological means.
Organisms Thought To Be Negligibly Senescent
Maximum Observed Life Span (years)
Aldabra Giant Tortoise
Emydoi dea blandingii
Eastern Box Turtle
Fresh water pearl mussel
Geoduck saltwater clam
Great Basin Bristlecone Pine
Lamellibrachia tube worms
Ocean Quahog clam
Red Sea Urchin
Acipenser transmontanus, acipenser
Do Creatures Displaying Negligible Senescence Die?
Creature exhibiting negligible senescence do not age and therefore do not die of age related conditions. These creatures do die however but from the following:
- habitat changes
- adverse environmental conditions
If there was a way of creating the condition of Negligible Senescence in humans would you take the treatment to achieve immortality?
What Causes Aging In Humans And Other Organisms
Most biologists attribute ageing or senescence in humans and other animals to 'telomeres'. Telomeres are the tiny caps on the ends of every chromosome that protect DNA from being corrupted. However, for every cell division, these telomeres become shorter. For each shortening, the cell duplicates itself a little worse than before. When they have become too short, the cell can no longer divide, a phenomenon known as the Hayflick Limit. The decay of telomeres is the biological root of death from old age. In many organisms, the enzyme telomerase maintains the telomeres during cell division. Once the organism reaches maturity, this enzyme stops functioning and the ageing process officially begins.
The Hayflick Limit can have a number of consequences leading to ageing in organisms:
- Mechanical senescence becomes an issue with many as when cells no longer divide, tissue cannot regenerate leading to wearing out of body parts such as feeding apparatus (teeth, mouth parts) and other body parts such as the gut and muscle tissue.
- Hormone-driven processes break down which reduce sexual drive, reduce reproductive processes, decrease the desire to feed and cause disease such as arthritis, arteriosclerosis and others.
Theories Explaining Negligible Senescence
Natural selection logically would not favor negligible senescence in most circumstances. Reproducing favorable genotypes leads to the reproductive individuals being favored. Once they have accomplished this feat, post-reproductive organisms become redundant and utilize resources to the detriment of reproductive and pre-reproductive individuals. There are, however, cases where negligible senescence is a favorable attribute.
1. Organisms that live in stable but crowded conditions favor longevity.
- In this condition new opportunities for space for mature individuals arise infrequently.
- Organisms that outlive their neighbors provide growing space for their own seedlings or larvae when they die.
- The Bristle cone pine and the Arctic quahog are two species which live in this type of environment and appear to use this strategy.
2. Planarians or flatworms have the capability to perpetually regenerate and thus, exhibit biological immortality.
- They are able to restore any damaged organ, including their brains.
- This capability gives them virtual immortality baring predation, accident or lack of resources.
- An equivalent enzyme to telomerase is present in asexual flatworms and is responsible for the flatworms 'immortality'.
- This enzyme does not appear to degrade at any point in the flatworm's life cycle thus, their telomeres remain in perfect condition allowing for their perpetual regeneration.
3. In general, asexual reproduction tends to lead to longer lifespans.
4. Organisms with extremely high infant mortality may favor negligible senescence for individuals reaching maturity to ensure longer reproductive capabilities for the few survivors.
5. Organisms such as the worm, Lamellibracia grow in nutrient poor environments. They have a slower growth rate and thus reach the Hayflick Limit at a much slower pace resulting in significantly longer lifespans.
6. Some organisms such as the Walleye have significantly longer lifespans when their habitat is in colder waters.
- For the Walleye, they experience a five fold increase in longevity in colder waters.
- Lower temperatures mean organisms reach maturity at a much slower rate.
- They reach the Hayflick Limit at a delayed rate greatly slowing the onset of age related deterioration.
7. Molting in crustaceans, such as the Lobster, replaces hard tissue, reducing wear and tear and thus, results in a longer life span.
de Magalhães, PhD, João Pedro. senescence.info. Some Animals Age, Others May Not. 2012
programmed aging. Negligible senescence. 2010
Wilkins, Alasdair. Negligible Senescence These immortal flatworms regenerate like real lifetime Lords. February 28, 2012..
Treating Senescence By Technological Means
A number of scientist are exploring technological means of increasing human longevity by studying those creatures which display negligible senescence. English transhumanist, Aubrey De Grey founded the S.E.N.S or "Strategies for Engineered Negligible Senescence" in 2002. Through this foundation, De Grey researches medical strategies for increasing the human lifespan with the ultimate goal of providing human 'immortality' through technological means. At this point, research is still a long way from achieving this goal.
Physican Terry Grossman claims to have remedies he proposes will keep many clients alive to the 125 year limit he feels humans can now aspire to. One of his clients is Ray Kurtzweil, famous inventor and futurist.