Be careful what you wish for. Even if immortality involves living forever in a physically healthy body much as it would be in the prime of life, it would take a miracle to make it bearable in the long run. Boredom can constitute an extreme form of suffering extended over millennia, and this time it would never end. This, to me, has long been the problem with the idea of eternal life in the Christian sense. I chose to resolve this by thinking of the human mind as a closed system within which entropy tends towards a maximum, in this case a form of insanity perhaps, and the options are therefore eternity without God with one’s mind filling up with emotional purulence and stagnating, or eternity with God which links one to the infinite, and therefore an open system, which by some miracle makes it bearable. Just a thought experiment. Olaf Stapledon seemed to have something like this in mind in the “cult of evanescence” – the idea that there is beauty in mortality, though this was in beings with a life expectancy of fifty thousand years.
Even so, people do generally not want to die and when they do it’s often because they find their current life unbearable for all sorts of reasons. Consequently, as a species we like to pursue things which might extend our lives. And there are a few animals who are kind of immortal. There’s a species of starfish, if I remember correctly, who starts off as a swimming form containing a tiny body of the future adult, who is then deposited somewhere and the rest of the larva swims off and doesn’t die. I’m not sure how this works because it makes it sound like eventually all the biomasse of the planet would turn into starfish vehicles, but so I’m told. There’s also a jellyfish who responds to injury and disease by ageing backwards and then growing back towards adulthood, and planaria, flatworms I used to keep as pets along with leeches as a child, way before I went vegan of course, do the same kind of thing. They respond to starvation by shrinking from twenty millimetres long to about three, after which they’re rejuvenated, and since they often reproduce by pulling themselves in half, the planaria living today are in a sense the same individuals as their distant ancestors who knows how many thousands or millions of years ago. Finally, there’s a bird called Leach’s storm petrel who doesn’t age in the usual way for vertebrates. Chromosomes have long bits on their ends called telomeres which prevent fraying damaging actual genes. Every time cells undergo mitosis in a living animal’s body, these shorten slightly until this damage starts to occur. In Leach’s petrel, and probably other related birds, telomeres lengthen with age. Procellariformes, the order including storm petrels, tend to live surprisingly long for animals of their size. A starling has a life expectancy of fifteen years, and is about the same size as one of these birds, but a Leach’s storm petrel can live to about thirty, and is likely to die of a non-age related cause such as infection, accidental death or being eaten.
Ageing could be seen as amounting to accidents which befall the inside of the body, sometimes to do with outside factors. As such, it may not be entirely realistic to think of a human being as simply getting older, and circumstances where humans were impervious to such diseases as cancer, heart disease, infections and diabetes would not also be circumstances where we were immortal because we could step off the kerb and be knocked down by the proverbial ‘bus at any point. It isn’t even clear whether a real distinction can be made between stuff going on outside the body and stuff going on inside it, so a simplistic assessment of how frayed your chromosomes are may not be terribly informative. In fact chromosomes that don’t fray may be problematic, a point to which I shall return.
We are of course chordates. I keep saying this but haven’t explained what it means. In case you don’t know, a chordate is an animal who at some stage in her life cycle has gill clefts, a stiffening back rod and muscle blocks. They often have a post-anal tail, i.e. the end of the digestive system and the genitalia are not always the end of the body. Humans usually but not always lack external tails but of course we do have them and they’re not even vestigial, as anyone who has fractured or bruised theirs will testify – it makes it painful and difficult to do number twos, for instance. We also have gill clefts as embryos and in fact our ears and jaws have evolved from them. If our notochords don’t regress, which normally happens by the age of four, they can eventually cause problems rather like benign tumours although they are usually asymptomatic.
We have, as I mentioned yesterday, evolved from fish-like invertebrate chordates, but the story doesn’t begin there. Early chordates were like sea squirts, and this time I’ll seek out a picture of an individual sea squirt rather than the admittedly pretty Haeckel-stle illustration I used previously:
Date
10 October 2006
Source
Own work
Author
Nhobgood Nick Hobgood
Sea squirts are I think completely brainless filter feeders as adults. The two siphons whose openings you can see suck water in and blow it out, trapping plankton in a mucous “net” which is then eaten. They have hearts which pump their blood sporadically in either direction arbitrarily and swap over sporadically. Their blood is also unique for being high in vanadium, possibly to make them poisonous to potential predators. This is an adult sea squirt, who lives facing head down, attached to the sea bed. Sea squirts are probably the ancestors of all vertebrates, but looking at one like that, and there are considerably stranger ones out there, it might be hard to guess. That’s because it’s an adult.
Sea squirts start off as tadpoles. Here’s a comparison of an ascidian (as they’re known) and a frog tadpole side by side:
The resemblance is remarkable and is a clue to how fish, our ancestors, came to be: a process called neoteny, which occurs a lot in evolution. Neoteny is when the younger form of an organism becomes its life-long form. It happened in humans when we evolved from other apes – we are more like baby apes of other species than their adults. Sea squirts start their lives as tadpoles, with vision and brains guiding their activity, seek out a suitable site to attach to, then do so head down, lose their eyes and brains and develop into their adult stage. There’s another group of invertebrate chordates called the larvaceans, so called because they stay in their larval form but are otherwise like juvenile sea squirts. This is one called Oikopleura:
It’s thought that fish evolved from these via lancelet-like forms, and therefore in a sense all vertebrates are larval. Now I don’t know if there is anything left of the genes or mechanisms which would allow a vertebrate to change from her larval to an adult form, but considering that humans spend all their lives, up to ten dozen years, in their larval form I sometimes wonder if we could do a little tweak and make ourselves metamorphose into our adult form as giant marine blind and brainless sea squirts. The adults live up to thirty years, and the tadpoles take only a day and a half to settle and start to change, so proportionately, assuming three score years and ten to be our life expectancy, we could live up to half a million years. But would it be worth it? Intuitively, a post-human sea squirt doesn’t seem to be much more than a sarcophagus or memorial, although knowing that the oceans are where all our family members end up living might change our attitudes towards their stewardship.
That scenario is of course quite fanciful and is almost certainly impossible, not to mention pointless, but it would effectively be immortality of a kind. There is another kind which is much more feasible and closer to home, which also involves the sea. I’ll start with dogs.
There is a tumour affecting dogs, wolves and coyotes referred to as Canine Transmissible Venereal Tumour. Thousands of years ago, a dog developed a tumour in his genitalia which could be passed on through coitus. That dog’s genome survived to some extent to the present day because he is now effectively that tumour. It contains his genome to some extent. It can also be passed on by other social contact such as licking and can also infect the nose. I found out recently that this tumour is one of the few survivors of the dogs who used to cohabit with Native Americans, incidentally. It can cause urinary obstruction and can recur after surgery. So there’s that.
Then there’s the famous Henrietta Lacks:
This is a photograph of Henrietta Lacks, legally speaking ALONE property of the University of Harvard, taken in the late 1940s. It will be removed solely on request of a member of her family or a legal representative of her family. It will absolutely not be removed on request of the University of Harvard.
I suppose it’s possible that you don’t know who Henrietta Lacks is. I’m not going over that again. Look her up if not.
Ms Lacks’s cervical cancer is good evidence that a transmissible tumour could occur in human bodies, even a transmissible venereal tumour. So far as anyone knows, it hasn’t happened yet. However, since the human population of this planet is increasing, the probability of the requisite mutations occurring is also increasing. This is how someone can, in a sense, achieve immortality.
HeLa cells are able to survive in vitro, which happens sometimes with certain cell lines but is fairly unusual. This is interesting because clearly lab conditions are very different from inside the body. It’s this ability to survive in a different environment which persuades some to regard them as a different species. The karyotype (chromosomal number) is also unique and not like that of most human somatic cells. HeLa cells are at least triploid for every chromosome if not more. Most animal cells are diploid, including a pair of each chromosome. HeLa have up to five copies of some, and there are also some mixed chromosomes and they can vary in chromosome number, which is not surprising since they’re cancer cells.
Cancer cells are in a sense a triumph of evolution. They mutate in order to avoid the “kill signal” sent to cells which have gone awry, they can survive while circulating in the blood out of contact with their usual environment and they are, ironically, much better at handling anærobic respiration. The reason this is ironic is that there’s a fake cancer treatment called lætrile which is based on the hypothesis that theyŕe worse at it, which as well as being dangerous even in a healthy person would quite possibly encourage the growth and spread of tumours. Cancer cells are also immortal, at least up until the point where they kill the host, and as CTVT, HeLa cells, a sarcoma found in hamsters and devil facial tumour which affects Tasmanian devils demonstrate, even beyond that point.
Author
Bernd Schierwater
Placozoa are a phylum of very simple multicellular animals consisting of a flat mat of cells which absorbs organic débris from the surface they’re living on and reproducing by shedding clumps of cells. They may also produce eggs. They are the simplest animals of all, and looked at another way they’re basically free-living tumours. HeLa cells can survive outside the body. I’ve also mentioned organoids before. These are the result of cells shed from the human digestive tract into sewers which multiply and form tiny organised bits of organs in sewage works. These too are human cells which can survive outside the body. They’re also nightmare fuel of course.
Putting all of those things together, a couple of possible scenarios arise. One is that there could be a human tumour transmissible through sexual contact, and it’s possible also that this could cause sterility. If that spread sufficiently and early enough in fertile life, it would probably reduce the population considerably and perhaps completely. That seems unlikely, however. I can easily see that there could be a tumour transmissible between humans in this way but it would eventually come to light, at least by the time it had reached parts of the planet which have medical facilities. However, the human species seems bent on its own destruction thanks to global capitalism. It’s hard to imagine what will happen once we’re gone, except that there may be a lot of nuclear power station meltdowns and poisoned areas around them, which however might stimulate evolution just as they did at Chernobyl with the mould which uses ionising radiation as a source of energy. I think it’s feasible, given the state of the planet right now, that it will bounce back after a period of chaos and instability. In order for that not to happen, it would mean that even microörganisms living in deep sea thermal vents would have to be wiped out. It could even be that evolution will be stimulated, as it often seems to be, by mass extinctions, and that there will be greater biodiversity in a few million years’ time than there was before the onset of the recent ice ages. Mammalian diversity, for example, has been in decline for millions of years even without the influence of human activity.
The Doomsday Argument, which I’ve mentioned from time to time in this blog, is a probability-based argument that the human species will soon become extinct. It emphatically does not depend on any specific apocalyptic process, which is important to note because it seems at first to suggest that our extinction will be caused by overpopulation. Rather, it works as follows, and I’m going to use out of date statistics and trends here to argue for it just to illustrate the principle. First of all, for the purposes of this argument to count as human it has to be possible that the individual concerned can have the thought that humans will cease to exist physically. It was estimated several decades ago, when the population was at around 4 000 million, that there had been 75 000 million humans from 200 000 years ago to the day the estimate was made, and at the time population doubled about every thirty years. The thought of human extinction has occurred in all sorts of situations throughout history, for instance in connection with Christian eschatology, and it’s easy to imagine a small tribe of people unaware of anyone else fearing for their survival back in Palaeolithic times. The probability that one is living at the end of human history increases as population increases, and given those figures, which are not now as accurate as they were because population growth is slowing, the final human birth is due to occur in about 2130 relative to my own birth in 1967. Of course this argument has many flaws. However, it requires human sentience.
Imagine this then. Humans as we know them die out. In the meantime, cell lines from a transmissible venereal tumour have come to thrive in sewage and nearby warm seas, perhaps parasitic on other animals. Humans will therefore survive and be immortal, just not in a state which can contemplate its own demise, but more like tumours living off other vertebrates living in the Caribbean or somewhere similar.
Immortality!
A Box Of Chocolates 