Deities in religion and myth live as the only beings capable of sustaining eternal life. For the rest of existence, death is considered inevitable. Although preventable external forces account for the majority of deaths, aging remains the only killer that is considered unavoidable. Aging brings with it some positive changes, such as increased strength and mobility. Other changes, however, negatively impact physical and mental capacity. What if scientists could discover the secret to controlling the aging process? With further investigation of particular and unusual organisms, this wacky fantasy can potentially become a reality.
Certain life forms have the ability to escape aging and fight death through biological processes. The hydra, an incredibly simple multicellular organism, provides an example of such a life form. Despite its small size, less than half an inch long, the hydra’s uncanny power to regenerate tissue can prove useful to humans. “The hydra is in a constant, stable state, and you can learn the basic biological principles of higher animals from it,” said Richard Campbell, a professor and researcher of cell and developmental biology at the University of California, Irvine.
The budding process, which replaces mating in these organisms, may allow the hydra, a simple polyp, to achieve immortality. With budding, a type of asexual reproduction, the offspring develops from a part of the parent. Thus, the Hydra got its appropriate name from the “Lernaean Hydra” of Greek mythology, a many-headed creature capable of replacing a missing head with three others in its place.
Similar to the Lernaean Hydra, the Hydra does not die easily due to its regenerative ability. This process makes it similar to another organism that can prevent aging: the planarian flatworm. Both organisms can recreate large amounts of tissue from a relatively small part of the original organism.
The fact that stem cells become unable to proliferate or multiply with age causes negative effects of aging in humans. A hydra’s stem cells, however, remain permanently active during the budding process, allowing it to avoid aging altogether. Research from the University of Kiel has shown that the FoxO gene allows a hydra’s stem cells to remain active throughout its life. “Surprisingly, our search for the gene that makes Hydra immortal led us to the so-called FoxO gene,” said Anna-Marei Böhm, a doctoral student at the University of Kiel.
Strangely, the FoxO gene also causes aging in humans. “Our research group demonstrated for the first time that there is a direct relationship between the FoxO gene and aging,” said Thomas Bosch from the University of Kiel. Because humans and Hydra share the same gene responsible for aging, Hydra could become pivotal in the future study of human anti-aging processes.
Surprisingly, other organisms besides the hydra and the planarian flatworm possess immortal capabilities. A microscopic organism classified as an extremophile can achieve more than simply escape death from aging. More commonly known as the “water bear” or “moss sucker”, the tardigrade has the ability to survive extreme conditions, such as severe heat exceeding the boiling point of water to temperatures slightly above absolute zero. In addition to the harsh temperatures, the tardigrade can survive pressures greater than those in the deepest ocean trenches and can live for 10 years without food or water. Furthermore, in 2007 the tardigrade became the first organism to survive in the vacuum of space.
How can the tardigrade persevere under these circumstances? Every time a tardigrade comes into contact with these extreme conditions, it enters a dormant state called cryptobiosis. In the study of biology, there are several different types of cryptobiotic responses. These types include anhydrobiosis, a response to lack of water; anoxibiosis, a response to lack of oxygen; chemobiosis, a response to harmful nearby toxins; cryobiosis, a response to low temperatures; and osmobiosis, a response to a large amount of solute in a solution in which an organism lives.
The strange nature of the tardigrade allows it to suffer from all known types of cryptobiosis! When subjected to cryptobiosis, the tardigrade does not appear to age and can rehydrate at any time and continue to roam the land in virtually any available habitat. Compared to Hydra, tardigrades have more traits in common with humans. In How to Find Tardigrades, Michael Shaw said, “…they are similar to us in some ways. They have a mouth, an alimentary tract, they eat food and excrete it just like we do.”
Obviously, the techniques used by potentially immortal organisms work differently. The investigation of the different organisms, therefore, can become useful for the human race in multiple ways. For example, the Hydra research could allow scientists to modify the FoxO gene to halt the negative effects of aging altogether. However, research on tardigrades would likely help develop ways to preserve living tissue for long periods of time.
Turritopsis dohrnii, nicknamed the “immortal jellyfish,” has the ability to defeat aging in a peculiar way. Basically, he can transform from an “adult” to a young jellyfish when needed. Their aging process could be described as opposite to that of humans, which can be useful in helping people maintain self-sufficiency at the end of life. “Increasing human longevity makes no sense, it is ecological nonsense. What we can hope for and work on is to improve the quality of life in our final stages”, said Stefano Piraino from the University of Salento.
Another organism, the lobster, has a relatively late aging cycle similar to that of the immortal jellyfish. Immortality in the lobster may seem unlikely, but the lobster actually becomes more functional with age. They grow larger by molting and become more fertile, but they do not return to a youthful state like immortal jellyfish. “These species, of course, still die. They contract disease, are injured or hunted. But, unlike humans, they don’t die as a result of their own metabolism; there doesn’t seem to be a life expectancy built into their lifespan.” cells,” said biologist Simon Watt.
Biological immortality also defines cells that are not affected by the “Hayflick limit”. The Hayflick limit shows the amount of cell division that will occur until the cells cannot divide. HeLa cells, cancer cells of the late Henrietta Lacks, represent a famous example of cells described as biologically immortal. This example of immortality could discover new ways to make cells divide continuously for life, similar to the cells of a Hydra.
Immortality may seem like too powerful a divine power for life on earth. It turns out that evolution has produced several organisms that can carefully achieve immortality. With intensive research on these organisms, the ability to prevent the debilitating effects of aging while exacerbating its positive effects may be possible in the not too distant future.