Becoming immortal would mean trading your body for that of a machine with the 2045 Initiative.Corbis Images

Can money buy immortality? Russian Internet mogul Dmitry Itskov believes that through his newest venture he'll be able to give humans the ability to live forever through his 2045 Initiative.

By the year 2045, Itskov's group aspires to create the technology in which the person's consciousness is transferred into "hologram-like human avatars." Itskov's idea might not be technologically possible now, but that doesn't mean it isn't plausible in the near future.

However, if there's one constant so far in the history of men pursuing the eternal life, it's that none of them have succeeded.

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Even 4,000 years ago, humans sought the secret to eternal life.Corbis Images

Dating back to the 18th century B.C., the Epic of Gilgamesh tells the story of the ancient Sumerian king of the same name. The epic poem is one of the oldest surviving literary works in history.

After Gilgamesh's close friend, Enkidu, becomes ill and dies, the tragedy leads the king to pursue the secret to immortality. Gilgamesh searches for Utnapishtim, the equivalent of Noah, who survived a flood created by the gods in an attempt to destroy humankind. Prior to the flood, the god of wisdom, Ea, tipped Utnapishtim off to the impending disaster, so Utnapishtim built a giant boat for his family and every animal could endure the event.

Gilgamesh didn't succeed in his quest, but he came to understand that his legacy through the kingdom he built would give him some measure of immortality.

Terracotta warriors adorned the tomb of China's first emperor.Corbis Images

After uniting China and becoming its first emperor, Qin Shi Huang became obsessed with the idea of living forever to preserve the power he had fought so hard to achieve.

In his later years, the emperor sought out the mythical elixir of life, which would confer immortality onto anyone who consumed it.

So obsessed was the emperor with living forever that he in fact died consuming mercury pills that he believed would extend his life.

Gunpowder might be the among the furthest things possible from the recipe for immortality.Getty Images

The search for the secret to eternal life didn't die with Qin Shi Huang. Successive Chinese emperors would pick up where he left off.

Around the 9th century, Chinese monks working on the recipe for immortality discovered gunpowder. The recipe they stumbled upon would be the foundation of a technology that would ensure the sudden and immediate mortality of hundreds of millions of people for centuries later.

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An illustration of the fabled king Prester JohnCorbis Images

Starting in the 12th century, legends emerged about the Christian kingdom of Prester John, a lost land to the nations of then Catholic Europe struggling against the Muslim Moors. Within his domain, Prester John was said to have lived a long and luxurious life thanks to his possession of, among other treasures, the fountain of youth.

For nearly five centuries, explorers sought out Prester John's kingdom, but never found this everlasting Christian stronghold.

Ponce de LeonCorbis Images

Perhaps among the most famous expeditions to pursue the secret to eternal life was that of explorer Ponce de Leon.

Prior to his first expedition to Florida, de Leon heard a story from native Caribbean islanders of a fountain of youth that would restore the vitality of anyone who swam in its waters. In the course of searching for the Fountain of Youth, as well as other riches on behalf of the Spanish crown, de Leon would explore what would become the state of Florida.

Stories of de Leon's quest to find the fountain only emerged after his death, so he may in fact never have sought the fountain. Today, however, St. Augustine, Fla., the oldest city in the United States, hosts a tourist attraction for the Fountain of Youth as a tribute de Leon's journey.

Turritopsis dohrniiPhoto: Turritopsis dohrnii Credit: YouTube

Human immortality may still be beyond the reach of technology, but eternal life might be biologically possible. Or at least that seems to be the promise of one species of jellyfish, Turritopsis dohrnii, reported on by the New York Times last year.

During the jellyfish's life cycle, it grows from a polyp into an adult. Instead of dying, however, in what earned the marine animal the nickname the Benjamin Button jellyfish, the adult instead regresses back to a polyp.

The effect appears to give the jellyfish the ability to live over of these cycles. How long the jellyfish can continue this rhythm and whether Turritopsis dohrnii could maintain it indefinitely is unknown.

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Patients at the Alcor Life Extension Foundation are placed into these large metal casings that are cooled to -320 degrees Fahrenheit.Corbis Images

Modern technology has made immortality seem somehow within reach, even if the science for eternal life still appears generations away.

That's the thinking behind one avenue of self-preservation: cryonics.

Cryonics is the process of preserving recently deceased individuals with the intention of reviving them using future medical science and technology. The individuals are frozen after their hearts stopped, so they have died legally, but before their brains are dead.

The Alcor Life Extension Foundation based out of Scottdale, Ariz., is one organization offering to preserve individuals in liquid nitrogen after death in the hopes of being able to live again.

To have the entire body preserve costs around $150,000. For $50,000, an individual can have just their brains held in cryonic suspension.

Telomeres are small strands of DNA at the tips of chromosomes.Corbis Images

Given how far and wide humans have traveled for the secret to eternal life, it would be a fitting end to the search if the key to immortality was hiding inside our genes all along.

Humans have 23 pairs of chromosomes that compromise our DNA, who we are. Each chromosome is tipped with stretches of DNA known as telomeres. Telomeres shorten each time our cells replicate as we get older. Eventually, if the telomeres become too short, the cell can die.

The idea goes that if there were a way to keep telomeres long to prevent damage to chromosomes and later cell death, then that could be a means of keeping an individual alive longer -- perhaps indefinitely.

The role telomeres play in cellular reproduction was a major scientific discovery, earning three scientists the Nobel Prize in Medicine in 2009.