Ever fancied immortality? Stupid question I know. Well, the jellyfish Turritopsis dohrnii may have the answer we’re looking for.It is one of the only animals that is capable of living indefinitely and its secret lies in a unique biological process known as cell transdifferentiation, which essentially reverts the animal back into an embryo. Don’t be too jealous though, the jellyfish often die early due to predators and disease.

Another similar organism is the hydra, a small freshwater animal which some scientists say could live forever. The method of preventing any ageing here is their production of a “FoxO gene”. Hydras injected with large amounts of this gene produce lots of stem cells, which can specialise into any cell, and aid the ability of a hydra to stop ageing.

Rather interestingly, this gene has also been found to be more prevalent in people who live to over 100 years than those who don’t. However, scientists can’t thoroughly prove this gene is the key to achieving human immortality, since this would require genetic modification, and ethical issues start arising here.

The humble lobster is another very interesting organism. It is said that lobsters’ longevity can be attributed to their continued production of a chemical called telomerase. This repairs any age-induced shortening of their genes, and helps to keep the older lobsters even more fertile than the young.

Many of the animals I have mentioned have not actually been observed to live to very old ages due to disease or predators. The oldest continuously living organism isn’t an animal but probably a colony of quaking aspen trees with one massive underground root system, known as Pando. Thought to be 80,000 years old, Pando is also the heaviest known organism.

The oldest single organism on earth is probably a tree in California that is supposedly 5,063 years old and is somewhat affectionately called Dennis. The oldest terrestrial animal ever known to have lived was a 255 year old Aldebra giant tortoise, called Adweita who died in 2006. To give some perspective, he was born before both the founding of the British museum and the Battle of Trafalgar.

Perhaps a more philosophical approach to immortality is the theory of biocentrism. The theory goes that life is at the centre of existence and reality, and it is life that creates the universe, not the universe that creates life. In other words, space, time and death are simply thoughts in our mind which we are taught and believe, but our lives are continuous.

It is possible that there are infinite universes, meaning that all possibilities are happening at once at this point in time. Thus when we die in one universe, we are born again and carry on living in another, and we carry on living in another. A respected scientist, Professor Robert Lanza, put forward this idea and has used quantum physics to provide evidence for it.

An experiment called the double slit shows that when a particle is fired toward a multi-slit barrier, and it is being watched by scientists, the particle only passes through a single slit. Whereas, when it is not watched, the particle passes through two slits at the same time.

Lanza suggests that this observation imposes reality onto the particle; we see it as only passing through one slit, much like we perceive ourselves as existing in one life. However, the particle is clearly capable of existing in two slits; could the same be applied to our view of ourselves?

This is all very interesting, but what can we do now to lengthen our mortal lives? One study found that taking a 30 minute walk three times a week can add 10 years to your life. Another found that being optimistic is the key, since stress provokes a damaging physiological response. A study from Yale University showed that people with a more positive view of ageing lived, on average, seven and a half years longer than those with negative views.

The data still showed this significant pattern even when factors such as age, gender and health were taken into account. Similarly, people who do volunteer work and help others tend to live longer, statistically speaking. In the end, just remember that the average age of nearly everyone’s body cells is just seven to ten years and only a very few cells remain throughout life. You’re younger than you think, but sadly no closer to being immortal.