Why are some animals seemingly immortal while others live only for a brief moment?
Several species such as the tardigrade, planarian and lobsters live for a very long time in comparison to us, and in particular in comparison to the Mayflies, who go from reproductive age to deceased in just 24 hours. The "immortal" species are in no way particularly stronger than other species as they too are very fragile and can parish under the wrong conditions. Tardigrades are very sensitive, and yet very durable and the same goes for the lobsters. When contemplating what they have in common, their phenotype i.e. the mare appearance does not give us any clues. So could it be in their genes?
Taking a closer look at the genetic structure of these three creatures (tardigrade, planarian and lobsters), one can find that all three have one particular thing in common. They have seemingly non affected telomere length. Telomere is to DNA as the plastic tips are to your shoestrings. It protects the genetic material from "untangling" and being damaged. More on Telomeres HERE.
So if telomere is at play here, how can we benefit from that fact? Well, we've known for a long time that we can affect telomere length through lifestyle. Telomere shortens if you expose your DNA to stressors, such as oxidative stress and toxic environments. Avoiding things that are toxic to your body, can maintain your telomere. But that is not the whole story.
Maintaining a long life span is not just a matter of telomere, even though it seems to be an excellent start to protect and prolong the process of cell degeneration, some species have done without telomere.
The conflict comes within our own genetics. Genes such as the P53 are there to protect us against cancer, shortening our telomere faster, but keeping those who have its desire polymorphism protected against cancer. Thus we trade a long life, for a healthier life. Why would evolution allow it?
It allows it because we are a species which on population level has (historically) not lived beyond the first tier of aging (50 years old). With better conditions, and elimination of all natural predators we've developed possibilities for longer lifespans, in fact to such point that we've experienced a group of men which actually outlive women. Well educated men outlive poor and uneducated women, which from a purely biological point of view is outstanding. We've truly mastered life span.
So beyond lifestyle, what else promotes longer lives? Well, the disposable soma theory is a compliment to the theory of the telomere. It simply says that reproduction is hard and demanding. If we delay reproduction, our somatic cells (which are involved in reproduction) will delay deterioration. Westendorp & Kirkwood did a study in 1998 in which they compared British aristocrats and the age at which they had children and noted that the older the parents were when the first child was born, the longer they lived (independently of health status or economic status). The results was only significant in women, but was seen as a trend amongst men as well. The biological hypothesis came from a study performed by Kirkwood in 1991 in which he delayed the reproductive age of drosophila files and expanded their life span by 20-70%.
So all in all, our genetics make it impossible for us to prolong life and at the same time sustain a good population as we can not prolong reproduction forever due to menopause, and due to the deteriorating condition of what makes a baby, the egg and the sperm.
Though biology seems to be the answer, all species which have come to live long lives have done so by implementing it in their genetic make up. We have implemented a great possibility for such scenario, if the conditions are excellent (which they never are). The sun sends radiation, there are toxins in most plants we eat, there are oxidative stressors in meat, there are predators and viruses.
So what can we do?
One suggestion is to bypass biology all together. Several projects are ongoing within medical technology that are making it possible for us to integrate technology in to our biology, one such pioneer is Kevin Warwick (pictured above). E.g. microchips that replace damaged cells in the hippocampus, or prosthetics that are attached to the brain so that amputees can control the movement and actions of their bionic limbs more smoothly. So instead of prolonging our biological expiration date, we might consider integrating our biology with a far more sustainable material, which will be easy to upgrade, download and repair. Instead of fearing a Terminator apocalypse, we should embrace a new step in our evolution of becoming the Terminators, rising above it all.