Archive for category old age
First off let’s pretend that I went through a lengthly apology for not posting here in quite a while. Secondly let’s pretend that you have accepted this apology graciously and are just happy to have another ramble by Ryan to read. That out of the way let’s meet todays star attraction…
This is Turritopsis nutricula. A few days ago I attended a conference on stem cell biology and this little gem of a beast cropped up. Before I go into why it is such a remarkable creature I’ll have to share a few facts about jellyfish. Jellyfish belong to the Cnidarian phylum and Cnidarians are the most distantly related group on Earth compared to all other animals. This is because Cnidarians diverged from the rest of us animals over half a billion years ago. Consequently they are quite different; they possess radial symmetry unlike us bilateria, they lack the highly conserved (not to mention ancient) hox genes and rather disturbingly their mouth and anus is the same hole. So what did I find particularly fascinating about this specimen? After all it isn’t very remarkable to look at. In spite of the picture T. nutricula don’t grow beyond half a centimeter and whilst the adults have nearly one hundred tentacles there are far more dangerous jellyfish out there. No the remarkable thing about T. nutricula is that it is biologically immortal.
Yup that’s right, immortal. T. nutricula start off life as larvae that attach to the sea floor and form a polyp, this polyp will begin to asexually produce small sexually mature jellyfish that will bud off of the polyp. Different species of jellyfish have different lifespans (hours-months) but after reproducing most jellyfish die. This is where T. nutricula differs; instead of meekly passing away a T. nutricula will begin to turn from a mature jellyfish back into a polyp! This polyp can then recreate the mature form and the cycle can continue indefinitely, literally rejuvenating itself over and over again.
The reason that this was bought up at the stem cell conference is because of the mechanism by which T. nutricula does this remarkable Benjamin Buttonesque trick. It occurs through a process called transdifferentiation. Cells start life as a stem cell that then undergoes a division forming two cells; one cell identical to the original and one more specialized cell. Transdifferation is the rare process by which specialized cells transform into a different type of specialized cell. This is as strange as brain tissue turning into muscle but this is how T. nutricula cheats death. It starts changing into an odd blob that sinks to the sea floor. This blob then anchors on and forms a polyp again. In reality T. nutricula does die thanks to the hazards of the sea (predation, disease etc) but efforts are now underway to keep them safe in the lab and observe their bizarre life cycle for as long as possible. So who knows? Perhaps future generations of stem cell biologists will be studying the same creatures that are even now being investigated for new insights into stem cell medicines. All I know is that I want one. I mean, who wouldn’t want the one pet that wouldn’t get flushed down the toilet after a few months?
One of the more remarkable gifts our technological world is the increase in our life expectancy. Even but a century ago the average life expectancy of a British man was half of that of today, even in the last two decades it’s gone up by five years. This increase has a myriad of reasons; an abundance of food, water, law and order, an increase in hygiene and sanitation and finally massive advances in medical science.
Extending one’s life and capability through innovative means is part of what makes us human. This trend of increasing life expectancy is one that doesn’t seem to be slowing down, indeed as we develop our biosciences we are gaining a deeper understanding as to the mechanisms of ageing. This occurred to me as a topic to talk about when I saw an article on the BBC news website reporting on the state of anti-ageing science. The report highlighted a few issues that were vehemently discussed in the comments, to get to the issues I’ll go over a bit of the science behind ageing.
We don’t fully understand every mechanism that goes on whilst we age. There are many contributing factors that we have discovered though; the most often touted cause of ageing is the shortening of telomeres. These are stretches of DNA found at the end of chromosomes, every time a cell replicates a bit of these telomeres are cut off. Over time this leads to shortened telomeres and a more likely chance of DNA damage. Other contributing factors include protein build up inside and outside of cells, DNA mutation and cellular replacement (many cell types die faster than they can be replaced, this is more apparent in the elderly). Designing therapies to counter all of these (and any undiscovered causes) would lead to a stabilisation and even reversal of the ageing process.
This is all interesting science but it has far reaching consequences for our society and people have a lot of different ideas about the ethics of life extension. Let’s imagine that effective treatments for all the causes of ageing are produced, in this scenario a regime of drugs is introduced to the public that when taken every day reverse your age to a physically fit, healthy 25 year old body and keep it that way. I’ve heard many arguments for why this is apparently a bad thing. A common argument is that we should not “play god” or “mess with the natural order”. The argument states that death is natural and any attempt to prevent death from old age is morally wrong. Whenever I am faced with this argument I simply ask the person if they take medicine, drive cars or use the internet. If the answer is yes then the argument for being unnatural seems pretty thin. Furthermore nobody has ever died from old age; people die from age related disease. Getting old is simply a slow wearing out until finally something vital fails. In curing old age diseases we ramp up the life expectancy. Are these people really going to advocate not researching medicines for these diseases? Are they going to tell elderly patients “we don’t have medicine for your kind. It’s natural! Accept it”?
Another popular argument is that of overpopulation. Proponents state that if we do not allow people to die the world will be overfull. I’m always sceptical of this claim; firstly it assumes that we cannot support this amount of people. In the year 1800 we could not have supported the 6 billion people we have today because it took over 200 years of technological development for us to be able to support us. The claim that there will be too many people assumes that this progression will not continue. Secondly the claim assumes that we will still give birth to as many people as we do today. Add to that the fascinating discovery made over the last century that if you give women rights, education and prospects they (shock horror) don’t want to spend their lives spitting out children like high-throughput human factories! The birth rate in countries with equal rights for women shrinks enormously. Couple this with the decreasing need to have so many children (you don’t need to have 12 in the hope 6 will survive to adulthood to take care of you) and we get a scenario of 1 or less children per adult.
For me life extension always makes me wonder; I am 21 years old; once I’ve lived that many years again I hope to have had kids, be married and have a good career. At that age I can expect that once I’ve lived that many years again I will probably be dead or close to it. But that is on the basis that near 80 is the age I will kick the bucket. If the regime of drugs we have supposed comes to pass and my life expectancy jumps from 80 to several hundred years I doubt my principles will stay the same. Why have kids at any age before 100? Why not spend a few centuries learning, travelling and establishing a good life before tying myself down with other humans to raise?
Personally I would work for decades then take a sabbatical (instead of retirement) and spend a few decades travelling, studying and generally being on holiday. I’m interested to know what you all think. Do you think age-stabilising drugs would be a good thing? What would you do if your life expectancy jumped by orders of magnitude? How do you think society would change? Ultimately these issues are nothing new, but as science marches on our life expectancy is shrinking over the horizon. So who knows? Perhaps one of you will be mulling over this blog on your 200th birthday…