In Pursuit of Immortality
12–26–16, Lefko
Alright team, let’s talk about death.
The biological term for aging is called “senescence,” and is formally defined as “gradual deterioration of function characteristic of most complex lifeforms, arguably found in all biological kingdoms, that on the level of the organism increases mortality after maturation. The word “senescence” can refer either to cellular senescence or to senescence of the whole organism.”
To give a little more meaning to this definition, let’s think about the implications of the terms:
Your body is made of about 37 trillion cells (and that doesn’t even include the microbes — which number about 40 trillion cells). Think about that for a second…generous estimates put the observable universe at 200 billion galaxies…that means your body has almost 200 times more cells than there are galaxies in our known universe!
Let’s back up a bit. You start from a single cell and expand to 37 trillion over the course of your life. To reach that point, you will experience 10,000,000,000,000,000 (10 quadrillion) cell divisions over the course of your lifetime! In order for life to continue those cells are continually metabolizing and functioning normally, splitting into new cells when they grow too big and killing themselves off when things start to go wrong.
When your cells split, you make a copy of your own DNA by replicating each of your chromosomes. Each chromosome is capped with a bundle of non-coding DNA, proteins, and RNA. Because the replication process is imperfect, each cellular split shortens the length of the chromosome. The telomeres play a protective role by allowing the process a buffer zone to lose some of the chromosome without cutting any coding DNA regions short. When telomeres get too short, cells stop dividing because it’s dangerous and could compromise the integrity of your genetic code.
In the lab, cells stop dividing and are no longer of use. In a human, that means when your cells stop dividing and can’t split to create “fresh” new cells that would revitalize your metabolism…there’s actually a number known as the Hayflick limit, which claims that human cells can’t split more than 40–60 times before senescence (most of the things that I have explained are very much an oversimplification and I am neglecting many other details of cellular aging, of course). This all translates to and correlates with — very roughly — the timeline of organismal aging. Organismal aging is what we commonly recognize as aging in humans…things like wrinkles, memory struggles, weak bones. Formally, it leads to things like “characterized by the declining ability to respond to stress, increased homeostatic imbalance, and increased risk of aging-associated diseases.”
Clearly, aging is an incredibly complex topic, and there are actually a few organizations who have devoted themselves to understanding this topic (see the SENS research foundation: http://www.sens.org/about/about-the-foundation, BioViva: http://bioviva-science.com/, and cryonics: https://en.wikipedia.org/wiki/Cryonics). Hopefully you now have an idea of some of the things that happen to your cells and your bodies.
So there are a few organizations devoted to extending life…are there any natural organisms for them to look to for inspiration? That is, are there any immortal organisms already in existence? Good question.
Very few animals come close to true immortality, and every one in the following list is susceptible to an external death-causing factor (think radiation, slicing and dicing, trauma, etc.):
- Rougheye rockfish (Sebastes aleutianus) — 205 years
- Olm (Proteus anguinus) — 102 years
- Painted turtle (Chrysemys picta) — 61 years
- Blanding’s turtle (Emydoidea blandingii) — 77 years
- Eastern box turtle (Terrapene carolina) — 138 years
- Red sea urchin (Strongylocentrotus franciscanus) — 200 years
- Ocean quahog clam (Arctica islandica) — 507 years
- Great Basin bristlecone pine (Pinus longaeva) — 4,713 years
Some other notable organisms:
Some animals like hydra, sea anemone and planaria are capable of total regeneration because they have stem cells that can regenerate every cell type in the animal. This means that the animal can constantly “rebuild” itself, so its cells don’t accumulate damage and don’t exhibit other signs of aging (like humans do). Intriguingly, hydra and planaria maintain their telomere lengths throughout their lives, and no one knows why.
Turritopsis dohrnii, or Turritopsis nutricula, is a small (5 millimeters (0.20 in)) species of jellyfish that uses transdifferentiation to replenish cells after sexual reproduction. Transdifferentiation is the process by which an organism can take a fully developed and defined cell, bring it back to a stem-cell-like state (aka “undifferentiated”), and then “redifferentiate” into a new defined cell that can replenish where the organism is missing some crucial cell. No word on telomeres in these bad boys though.
Lobsters. Research suggests that lobsters may not slow down, weaken, or lose fertility with age, and that older lobsters may be more fertile than younger lobsters. This one has a really interesting twist. There is an enzyme called telomerase which replaces telomeres on DNA as cells divide. This enzyme is very active as organisms are first developing but loses activity with age, which is why telomeres shorten with age. In lobsters, however, telomerase doesn’t stop working. That being said, lobsters are not immortal they really only live to 30–50 yrs). Lobsters grow by moulting which requires a lot of energy, and the larger the shell the more energy is required. Eventually, the lobster will die from exhaustion during a moult. Older lobsters are also known to stop moulting, which means that the shell will eventually become damaged, infected, or fall apart and they die.
So, let’s summarize. What do we know about aging? It sucks, telomeres are probably involved, there are some animals that live long as fuck, and we really have no idea how to put it all together and apply it to humans…yet
Anyway boyos, that was my foray into the search for immortality. Hope y’all enjoyed
