Living Fossils: How Immortal Organisms Exist and Can Man Also

How to determine the maximum life span

The maximum lifespan is

a theoretical number, the exact value of which cannot be determined using any finite amount of data about a particular organism.

In this regard, the maximum life span is usually determined by the best known maximum number of years to which the organism has lived.

However, individual lifespan is a statistic 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.

The maximum life span empirically depends on several characteristics of the animals.

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.

The typical relationship breaks down in the case of rocksdogs. Large breeds of dogs, although they reach puberty more slowly, live significantly less, the difference is 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 an unlimited existence. Studies confidently classify 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 body. However, such claims have two problems.

The basic 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 a 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 body's survival in the environment.

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

although today it is already possible to noticeably increase the averagehuman life expectancy through factors such as overall improvement in health care, an important issue remains to increase the maximum life expectancy, which can only be achieved by influencing the speed of the aging process.

Researchers have made some progress inAnimal Models: Through factors such as dietary calories, genetic changes, or hormone administration, it has been possible to increase or decrease the lifespan of 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 by limiting the calorie content of the diet while maintaining its usefulness.

By reducing calories by 40-60% in the diet of rats, mice and hamsters, starting the diet before reaching puberty, the average life expectancy increases by 65%, and the maximum - by 50%.

In the case of fruit flies and nematodes Caenorhabditis 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 probability of cancer (for example, rodents) and animals with pathologically low life expectancy as a result of exposure to radiation or chemicals with mutagenic effects.

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 at first the researchers tried to findbiochemical basis of the effect of limited calorie intake on life expectancy, later many new genes were found that have a similar effect. Several strains of mice exist today, with lifespans longer than wild-type mice.

The idea of genetic changes developed later ina new approach - 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 NationalThe Cancer Research Center (Centro Nacional de Investigaciones Oncologicas, CNIO) under the leadership of its director, María Blasco, proved that the lifespan of mice can be increased by a single injection of a drug that directly affects the genes of an animal in adulthood.

They did this with gene therapy, a strategy never 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 animal health by delaying the development of age-related diseases - such as osteoporosis and insulin resistance - and improving aging indicators 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 increasethe lifespan of the nematode Caenorhabditis elegans. To do this, they used mutations of proteins from two metabolic pathways that affect lifespan: the DAF-2 molecule involved in insulin signaling (it usually prolongs life by 100%), and the RSKA-1 (S6K) protein involved in MTOR signaling - rapamycin targets (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 futuresuch drugs may appear in the future. 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 (an analogue of myostatin).

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 lifespan through a mechanism that does not depend on 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 being carried out in animals and cannot offer the replacement of any parts of the aging body with "new" artificially grown parts.

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 this methodis based on the well-known fact that at cryogenic temperatures no significant changes occur in a biological object for thousands of years, and gives the proponents of this method hope that medical technologies of the future will be able to restore a cryopatient and even rejuvenate, 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 the processes of lifeartificial means. Breathing, heartbeat, and other involuntary functions can 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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