The old age question, revisited

zenoandthetortoise

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As the original thread was closed, I'll revisit on my own.

It is reductionist (and circular) to state that nothing dies of old age, but only specific organ failure, when age may in fact be the cause of the organ failure. That would be the equivalent of listing 'heart stopped' as cause of death, whether the heart stoppage was precipitated by leprosy or ninja assault. The statement would be true, but lacking some significant details.

There are in fact 'expiration dates'; teeth wear down, eyes develop cataracts, joints destabilize or otherwise fail. On a deeper level, there is what's called the Hayflick number, a maximum number of cell divisions that are even potentially possible and this varies tremendously by species. If you want to be scientific about the question, the typical maximum lifespan calculation is the mean value of the longest lived 10% of a given species. At that point, metabolic collapse at either the cellular, organ, or system level is expected.
 

Yvonne G

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Since you seem to be looking for a debate, would you like me to move this to the debate section?

A tortoise never loses the ability to lay viable eggs or to fertilize eggs. They can lay or fertilize right up to the end of their life. So why should we think that other parts in their bodies would wear out and get old?
 

zenoandthetortoise

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Since you seem to be looking for a debate, would you like me to move this to the debate section?

A tortoise never loses the ability to lay viable eggs or to fertilize eggs. They can lay or fertilize right up to the end of their life. So why should we think that other parts in their bodies would wear out and get old?
On the contrary, I was not looking for a debate, I was looking to add clarity. You are of course free to relocate as you feel appropriate.
Regarding your question; I'll accept the premise as stated and without corroboration, because it does not contradict the information presented. As to why you should think one way or the other, I'd suggest evidence and information as opposed to extrapolated conjecture.
 

Iochroma

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Or perhaps the most important "thing" that wears out, is the immune system. The ability to fight infection is integral to survival. Maybe 250 years of life is all a tortoise's system can do before it is overcome.
 

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Several years ago I read a "Reader's Digest" article about research being done on tortoise longevity. The author made specific mention of what was going on at a cellular level, and pointed out several examples of tortoises that were documented and verified at 150+ years of age. Also listed were the CODs of these old animals and in each case something "external" killed them. One was run over by a car. One fell out of the cannon port high on a wall in a Caribbean fort and smashed on the rocks below, etc...

According to this author, there was something different going on at the cellular level than what takes place for us or most mammals. I would love it if one of our expert internet searchers could find that article somehow and share it here. It must be somehow archived somewhere. I would estimate the time frame to be mid 90's if memory serves.
 

zenoandthetortoise

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So I'm going to try again for clarity. The OP of the initial thread asked if anyone had experience with a tortoise dying of old age and the replies negated the question as being invalid; the scenario did not exist. This rebuttal was based on reasoning or conjecture, which by the way, is not a pejorative. However, it does not take the place of actual information which I was hoping to provide. Regardless of my experience or expertise, the Hayflick limit is a real phenomenon that exists; you could google if so inclined. Mitotic divisions result in ever shortening teleomeres; cyclobutane pyrimidine dimmers and other lesions that inhibit transcription accumulate and at some point exceed the capabilities of nucleotide excision repair. This is old age at a cellular level, apart from auto accidents, infection or metabolic failure, the latter two being effects rather than first causes.
 
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tortadise

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Found this rather interesting researching this topic. Danish PHD student and his views. Of course he described no evidence or scientific backing, which I'd like to see too. But the problem with that is knowing these animals live much longer than we do. At what constant or variable could we properly test laboratory findings of immunosenescence? I suppose it could be handed down from generation of research to generation. But how many animals need to be tested to prove this theory.

http://zoophysiologist.tumblr.com/post/42360371334/why-turtles-dont-age
 

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The Hayflick in essence become moot with at least some chelonians. There cellular/molecular mechanisms do not cascade to senesce before an actuarially cause of death occurs. They reproduce at an ever better advantage within a population as they age. The progression of age solidifies the traits that make them biologically immortal. The case in point is in peer reviewed sci lit written by Justin Congdon with Blanding's turtles. Here is one source that can be accessed for free http://onlinelibrary.wiley.com/doi/10.1046/j.1420-9101.1993.6040547.x/abstract

Several species also exhibit the trend that as females grow older/bigger they lay more/larger eggs that have neonates better able to survive. Any given population maintains their niche space with two ends on the spectrum of neonate placement and survival. Any year that incubation favors the species several will hatch and use niche space, then those that are best suited will persist. Young females that lay smaller fewer eggs are a large enough proportion of the population that if they are not taken out by some random event before they age, at least their offspring still carry those traits forward albeit with the relatively wimpy part of their potential or actual reproductive life history.

Green sea urchins are noted to have some mechanism such that they have no age senesces, again the are biologically immortal. All sea urchins do not have the same resilience as greens, so no doubt all chelonians do not, but at least some do, and depending on the species and population examined, at least some are biologically immortal.

From one of those -pedia pages. . .

Biological immortality refers to a stable or decreasing rate of mortality from cellular senescence as a function of chronological age. Various unicellular and multicellular species may achieve this state either throughout their existence or after living long enough. A biologically immortal living being can still die from means other than senescence, such as through injury or disease.

This definition of immortality has been challenged in the new Handbook of the Biology of Aging,[1] because the increase in rate of mortality as a function of chronological age may be negligible at extremely old ages, an idea referred to as the late-life mortality plateau. The rate of mortality may cease to increase in old age, but in most cases that rate is typically very high.[2] As a hypothetical example, there is only a 50% chance of a human surviving another year at age 110 or greater.

The term is also used by biologists to describe cells that are not subject to the Hayflick limit.
 

zenoandthetortoise

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Found this rather interesting researching this topic. Danish PHD student and his views. Of course he described no evidence or scientific backing, which I'd like to see too. But the problem with that is knowing these animals live much longer than we do. At what constant or variable could we properly test laboratory findings of immunosenescence? I suppose it could be handed down from generation of research to generation. But how many animals need to be tested to prove this theory.

http://zoophysiologist.tumblr.com/post/42360371334/why-turtles-dont-age
Great article. Thanks for sharing. This thread had devolved into one of the more confusing/frustrating conversations I have had of late.
I suspect a cell culture line could be used to establish a model that would not be dependent on the actual lifespan of the animal. Lack of Immunosenescence would certainly be evidential of longevity, but actual pluripotentency or something like it would indicate that old age is non factorial.
 

theguy67

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Where exactly were Cnidarians used as an example? Urchins are echinoderms, which do not follow that life cycle. Also, I believe Will was using them as an example of the potential some animals have which is relevant to the discussion (which was after the article discussing turtles).
 
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mike t

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As the original thread was closed, I'll revisit on my own.

It is reductionist (and circular) to state that nothing dies of old age, but only specific organ failure, when age may in fact be the cause of the organ failure. That would be the equivalent of listing 'heart stopped' as cause of death, whether the heart stoppage was precipitated by leprosy or ninja assault. The statement would be true, but lacking some significant details.

There are in fact 'expiration dates'; teeth wear down, eyes develop cataracts, joints destabilize or otherwise fail. On a deeper level, there is what's called the Hayflick number, a maximum number of cell divisions that are even potentially possible and this varies tremendously by species. If you want to be scientific about the question, the typical maximum lifespan calculation is the mean value of the longest lived 10% of a given species. At that point, metabolic collapse at either the cellular, organ, or system level is expected.
Well said.
 

zenoandthetortoise

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Where exactly were Cnidarians used as an example? Urchins are echinoderms, which do not follow that life cycle. Also, I believe Will was using them as an example of the potential some animals have which is relevant to the discussion (which was after the article discussing turtles).
My apologies. This is the danger of typing and editing on a phone, particularly while driving.
In the paragraph that was inadvertently deleted, I questioned whether it was in fact the green sea urchin he had in mind or the oft cited Red Sea urchin, Strongylocentrotus franciscanus, (biologists often use Latin for clarity). The next example referenced is typically
Turritopsis dohrnii, the so-called 'immortal jellyfish' and here is where the Cnidarian reference would have made more sense. Nevertheless, the point stands- both phyla are orders of magnitude less complex that the vertebrates under discussion, and I would suggest irrelevant, though there's clearly some contention on that point. Whether the contention is sincere or not is immaterial to me as the dialogue did advance past the conjecture level, and I'm calling that a win. Anyway, for anyone interested here is an article abstract describing the teleomere phenomenon in Red Sea Urchins:

FEBS Lett. 2006 Aug 21;580(19):4713-7. Epub 2006 Jul 24.

Lack of age-associated telomere shortening in long- and short-lived species of sea urchins.

Francis N1, Gregg T, Owen R, Ebert T, Bodnar A.

Abstract


The red sea urchin, Strongylocentrotus franciscanus, can live in excess of 100 years while the sea urchin Lytechinus variegatus has an estimated lifespan of only 3-4 years. In an effort to understand the molecular mechanism underlying the difference in their longevity we characterized telomere biology in these species of sea urchins. Telomerase activity was found throughout early stages of development in L. variegatus and is maintained in adult tissues of L. variegatus and S. franciscanus. Terminal restriction fragment analysis indicated a lack of age-associated telomere shortening. These data suggest that long- and short-lived sea urchins do not utilize telomerase repression as a mechanism to suppress neoplastic transformation.

And here's one describing why telomerase in chelonians is different, and in fact varies between blood cells and epidermal cells.

Genes Genet Syst. 2008 Oct;83(5):423-6.
Shorter telomere length with age in the loggerhead turtle: a new hope for live sea turtle age estimation.
Hatase H1, Sudo R, Watanabe KK, Kasugai T, Saito T, Okamoto H, Uchida I, Tsukamoto K.

Author information

Abstract

We verified whether telomere length shortens with age in the loggerhead sea turtle (Caretta caretta) by measuring telomere lengths (relative telomere to single copy gene [T/S] ratios) in whole blood and epidermis from 20 captive individuals with a real-time PCR method. There was no significant correlation between age and relative T/S ratios in blood. Although the correlation between age and relative T/S ratios in epidermis was not significant, older turtles had smaller relative T/S ratios in epidermis. It was thus demonstrated that telomere length in epidermis could be a useful age estimator for sea turtles. Relative age information obtained with this simple, rapid, non-invasive technique may help to advance our understanding of the ecology of endangered sea turtles. This is the first publication on age-related changes in telomere length among chelonians.
 

turtlemanfla88

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Hey I am no expert ,but I have a question for all of you. i pay attention to my animals just like the rest of us. Well my oldest pair of Kwung-Tung/red -neck pond turtle/ nigricans are close to 30 years old well in the last couple of years I observed something around the same time each year they start breathing heavy and gapping and acting weird will not eat foods they eat all year long. I bring them in and start feeding them earthworms and pellets slowly through winter and then they do again during same time in the summer. This old pair is amazing once produced over 45 eggs in a season.I remember when nobody wanted babies for $25 dollars so I kept them I am going to be heartbroken ,but like the late David Lee gave me great advice build your assurance colonies for the species you work with. I know living in FL I get sinus problems which I never had growing up in NY. Could turtles and tortoises have sinus problems?.
 

leigti

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Hey I am no expert ,but I have a question for all of you. i pay attention to my animals just like the rest of us. Well my oldest pair of Kwung-Tung/red -neck pond turtle/ nigricans are close to 30 years old well in the last couple of years I observed something around the same time each year they start breathing heavy and gapping and acting weird will not eat foods they eat all year long. I bring them in and start feeding them earthworms and pellets slowly through winter and then they do again during same time in the summer. This old pair is amazing once produced over 45 eggs in a season.I remember when nobody wanted babies for $25 dollars so I kept them I am going to be heartbroken ,but like the late David Lee gave me great advice build your assurance colonies for the species you work with. I know living in FL I get sinus problems which I never had growing up in NY. Could turtles and tortoises have sinus problems?.
Maybe put this in the health section and one of the vets on the forum could answer that. I am not up on tortoise and turtle anatomy but if they have a sinus they could have a sinus problem :) are those types of turtles native to where you live? If not maybe the different climate and weather etc. could be bothering them that time of year. We are totally off-topic now by the way :) like I said start a new thread with this and see what answers you get from more experienced people
 

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Is your pint pot half full or half empty. Depends how you view life. The outcomes the same. 6 of 1, or 1/2 dozen of the other.
Is my grandma so fit for her age because she has 5 sugars in her tea. However her teeth are dead. :)
 

Tortoisefan

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This whole thread hurts my head... I have a dictionary and a biology book out and I am trying not to drool on myself. Here's my science they spend most of their life living in slow motion so it takes longer for them to die. There! Now on to solving the double slit experiment.
 

Anyfoot

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This whole thread hurts my head... I have a dictionary and a biology book out and I am trying not to drool on myself. Here's my science they spend most of their life living in slow motion so it takes longer for them to die. There! Now on to solving the double slit experiment.
Hi there Totoisefan, Welcome, Honest you can learn about torts aswell on this forum, its excellent.
Theres this women called yvonne G, she is the wise one and knows a heck of alot.
Its hurting your head, I just let it ride over mine:) I'm only just getting to grips with winning trophy points for the first time in my life. fpmslf:D I used to be round back of bike shed at school whilst others were out earning there trophies.;)
Anyway everyone, A mouse lives 1yr an elephant lives 50yrs and a tortoise lives 150yrs, They all have roughly the same amount of heartbeats in there life span.
Their hearts died of old age through usage and in turn they died. So was this classed as death of old age or death of a vital organ that died of old age.:p
 

Kapidolo Farms

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"There (Their) cellular/molecular mechanisms do not cascade to senesce before an actuarially cause of death occurs."

Congdon suggests that as Blanding's reproductive capability/capacity increases with age, that other life history traits are also not the norm. That norm being reproductive senescence followed by age senescence. Most vertebrates experience actuarial death or reproductive senescence followed by age senescence. Mechanism known or unknown, it is a reasonable assertion that based on similarity in some life history traits (bigger and more eggs with size and age in some chelonians) that those same chelonians die an actuarial death before a senesce death.

That is literally what biological immortality means, death by stochastic event before death by age degeneration. If an average adult tortoise has a 1:100 chance of dying due to predation, poor retreat choice, lighting strike, whatever, in any one year, then a single cohort of 100 individuals will have one that lives to the age of 100, plus years to reach adulthood. In some cases there will be individuals that live even much longer. In some cases it will be a 1:200 ratio, those are population dependent ratios.

Captive tortoises are not in a 'normal' population. But captives are the individuals whose age can best be guessed, as people have recorded their individual life. Congdon's study (published over several venues) is one of the best for long term wild animals. The assertion that wild tortoises die due to an actuarial cause before age degeneration is reasonable.
 

ascott

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Every living creature has its "shelf life"...then factor in the daily events that either increase or decrease the bottom line...lets not forget about the soul of a living creature (each has their own idea of what the word "soul" represents), the will to live as well as the will to not.....oh, and there is no scientific report that I have ever seen that proves or disproves this belief 100% without waiver....there are a lot of theories, but no PROOF.


 
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