How to determine the maximum life span
Maximum lifespan is
In this regard, the maximum lifespan is usually determined by the best known maximum number of years to which the organism has lived.
However, individual lifespan is a statistical variable, and this approach is highly dependent on sample size, making comparisons between species difficult.
The end of an individual's existence is usually consideredthe moment of death, that is, the moment when irreversible changes in the body reach such a stage that the individual no longer retains his characteristic organization.
However, there is often a relativelya short period during which it is difficult to tell whether the organism is still alive, although in most cases this period is quite short and does not pose a problem in determining the maximum life span.
Hydra (Hydra oligactis), a potentially immortal animal.
What determines life expectancy
The maximum lifespan is very strongdiffers between animal species. It was noted that the difference between the average and maximum life expectancy also significantly depends on the species, and is determined by the survival strategy.
Maximum lifespan is empirically dependent on several animal characteristics.
- Fertility of an animal: the more offspring an animal gives, the less it lives.
- Animal size, brain size, and metabolic activity. For example, smaller animals tend to have shorter lifespans, while larger animals have a longer lifespan.
Typical dependence is violated in the casedog breeds. Larger breeds of dogs, although they reach sexual maturity more slowly, live much shorter lives, the difference reaches about 2 times between the largest and smallest breeds.
This is the kind of relationship that also has for birds, but birds in general live longer than mammals, despite higher body temperatures and rates of natural metabolism.
Low energy expenditure and the possibility of constant growth explain the long lifespan of some vertebrates. For example, the Galapagos tortoise (Geochelone nigra) can live up to 177 years, and some fish, such as sturgeon, reach an age of more than 150 years. However, the life span and aging of these animals is very poorly studied.
What species can live endlessly
It is likely that some organisms are potentiallyimmortal. If an accident does not stop life, they may be capable of unlimited existence. Research confidently classifies sea anemones and freshwater hydras as such organisms. In addition to them, this ability is often attributed to certain fish and reptiles, especially those that are capable of unlimited growth of their bodies. However, there are two problems with such claims.
The basal metabolism and activity of these animals is very low, usually tens of times lower than the corresponding characteristics of mammals and birds, which provides for much slower aging.
In addition, unrestricted body growth helps the animal slow down or even stop aging, but it is the increase in size over time that reduces the survival of the organism in environmental conditions.
For example, the inability to obtain sufficientthe amount of food, loss of secrecy and mobility, and many other negative factors in the aggregate, sooner or later lead to the death of the body. Thus, it is difficult to distinguish between death directly from old age and death from external causes.
Carolina box turtle. One of the types of animals whose body does not age
Attempts to increase life expectancy
A large branch of research in gerontology is the attempt to increase life expectancy, especially in humans. X
However, today it is already possible to significantly increase the averagehuman life expectancy through factors such as general improvements in medical care, an important issue remains the increase in maximum life expectancy, which can only be achieved by influencing the rate of the aging process.
Researchers have made some progress onAnimal Models: Using factors such as calorie intake, genetic changes, or hormone administration, lifespan has been increased or decreased in several model organisms.
However, it has not yet been possible to continue human life, although advances in gerontology have already made it possible to treat several diseases that are characterized by accelerated aging.
- Reducing the calorie content of food
The simplest method of influencing the lifespan of some animals is to limit the calorie content of the diet while maintaining its nutritional value.
By reducing calories by 40-60% in the diet of rats, mice and hamsters starting before puberty, average lifespan increases by 65% and maximum lifespan by 50%.
In the case of fruit flies and nematodesCaenorhabditis elegans, the effect of slowing aging and increasing longevity is achieved immediately, regardless of the age of the animal.
- Antioxidants
Some impact on life expectancyhave antioxidants. Adding antioxidants to the mammalian diet increases average lifespan by up to 30%, but no change in maximum lifespan.
Antioxidants have the greatest effect onanimals with a high risk of cancer (for example, rodents) and animals with pathologically low life expectancy as a result of exposure to radiation or mutagenic chemicals.
Perhaps the effect of antioxidants is limited to a decrease in the likelihood of certain diseases, rather than changes in the rate of aging of the whole organism.
- Genetic changes
Much work has also been done in the direction of genetic changes that affect the lifespan of model organisms.
If researchers first tried to findbiochemical basis of the effect of caloric restriction on life expectancy, many new genes were later found that have a similar effect. Today there are several strains of mice, with lifespans longer than wild-type mice.
The idea of genetic changes developed later inA new approach is Strategies for Engineering Negligible Senescence (SENS), in which researchers are trying to design a genetically modified organism with a significantly longer lifespan.
Life Extension Strategies
- Gene therapy
In 2012, scientists from the Spanish NationalCancer Research Center (Centro Nacional de Investigaciones Oncologicas, CNIO) under the leadership of its director María Blasco have proven that the lifespan of mice can be increased by a single injection of a drug that directly affects the genes of the animal in adulthood.
They did this using gene therapy, a strategy never before used to combat aging. The use of this method in mice has been found to be safe and effective.
Mice treated at one year of agelived longer on average by 24%, and at the age of two years - by 13%. In addition, the treatment led to significant improvements in the animals' health, delaying the development of age-related diseases such as osteoporosis and insulin resistance and improving indicators of aging such as neuromuscular coordination.
This study “shows that you candevelop an anti-aging gene therapy based on telomerase without increasing the incidence of cancer, ”the authors argue. Thus, gene therapy is becoming one of the promising areas of the emerging therapeutic area of radical life extension and aging arrest.
- Life-prolonging mutations
Researchers have achieved a fivefold increaselifespan of the nematode Caenorhabditis elegans. To do this, they used mutations in proteins from two metabolic pathways that affect lifespan: the DAF-2 molecule, which is involved in insulin signaling (it usually prolongs life by 100%), and the RSKA-1 protein (S6K), which is involved in MTOR signaling. - target of rapamycin (it usually prolongs life by 30%).
To the surprise of scientists, together, thanks to synergy, they gave a fivefold increase in life expectancy (instead of the expected 130%).
- Drug therapy
The latest research shows that in the near futureIn the future, such drugs may appear. Already, some of their prototypes can be named, these are metformin and acarbose (anti-diabetic drugs for the treatment of type 2 diabetes in humans), rapamycin (an immunosuppressant that suppresses the MTOR pathway), a protein called GDF11 (a myostatin analogue).
Until recently, this list includedalso resveratrol and melatonin. In the near future, it is expected that this list will be replenished with synthetic analogues of the fasting hormone - FGF21, which, by increasing the level of adiponectin, can increase life expectancy through a mechanism independent of AMP kinase, MTOR and sirtuin pathways.
Therefore, therapy with FGF21 in combination withby interfering with the pathways of AMP, MTOR and sirtuins, may have a synergistic effect similar to the above 5-fold increase in nematode lifespan by double mutation.
- Organ cloning and replacement
Biotechnology and cloning researchparts and stem cells are currently conducted on animals and cannot offer replacement of any parts of the aging body with “new” parts grown artificially.
Brain transplant experiments conducted onmonkeys and dogs in the middle of the 20th century, failed due to the processes of rejection and the inability of the body to quickly restore the neural connections that ensure the functioning of the body. Proponents of body replacement and cloning argue that the necessary biotechnology may come in the future.
- Cryopreservation
Rationale for using this methodis based on the known fact that at cryogenic temperatures no significant changes occur in a biological object for thousands of years, and gives supporters of this method hope that future medical technologies will be able to restore a cryogenic patient and even rejuvenate him, thus prolonging his life.
For cryopreservation of humans or animalsfrozen to ultra-low temperatures, using cryoprotectants to prevent the appearance of ice crystals. Cryonics advocates hope to revitalize cryonics patients through organ growing and nanotechnology.
- Slowing down life
Slowing down life - slowing down life processesby artificial means. Breathing, heart beating, and other involuntary functions may occur, but they can only be detected by special means.
Experiments were carried out on dogs, pigs andmice. Strong cooling is used to slow down functions. Scientists replace the blood of animals with chilled solutions (saline) and they are in a state of clinical death for three hours. Then the blood is returned and the circulatory system is started with the help of electrical stimulation of the heart.
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