Worms and death

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If you've seen BladeRunner, you know the short soliloquy at the end by one of the android replicants, Roy, as he's about to expire from a genetically programmed early death.

"I've seen things you people wouldn't believe. Attack ships on fire off the shoulder of Orion. I watched c-beams…glitter in the dark near Tanhauser Gate. All those…moments will be lost…in time, like tears…in rain. Time…to die."

There's an interesting idea here, that death can be an intrinsic property of our existence, a kind of internal mortality clock that is always ticking away, and eventually our time will run out and clunk, we'll drop dead. There is a germ of truth to it; there are genetic factors that may predispose one to greater longevity, and in the nematode worm C. elegans there are known mutants that can greatly extend the lifetime of the animal under laboratory conditions.

However, in humans only about 25% of the variation in life span can be ascribed to genetic factors to any degree, and even in lab animals where variables can be greatly reduced, only 10-40% of the life span variation has a genetic component. There is a huge amount of chance involved; after all, there aren't likely to be any genes that give you resistance to being run over by a bus. Life is like a long dice game, and while starting with a good endowment might let you keep playing for a longer time, eventually everyone craps out, and a run of bad luck can wipe out even the richest starting position rapidly.

In between these extremes of genetic predetermination and pure luck, though, a recent paper in Nature Genetics finds another possibility: factors in the organism that are not heritable, yet from an early age can be reasonably good predictors of mortality.

Here's the experiment. Start with an isogenic line of Caenorhabditis elegans; these are all nearly perfectly identical genetically, eliminating most of the possibilities of a genetic component. When raising a colony of isogenic animals, of course, they don't all abruptly kick the bucket on the same day at the end of their maximum lifespan (under two months for these worms), but instead a few die every day until they are all gone. The question is, is there anything that will allow one to predict whether a newly hatched worm will die in one week, or in 8 weeks?

Into this worm strain, a marker construct is introduced. The construct consists of a copy of some regulatory elements from the worm genome, attached to the sequence for Green Fluorescent Protein (GFP), a gene that glows bright green. Whenever the normal gene controlled by the regulatory elements is turned on, the GFP gene is also turned on. This is a fairly common technique in developmental biology, to take advantage of the regulatory circuitry in the cell to turn on a gene we can see. It's very clever—it means every time the gene we're interested in is active, the whole cell glows like a Christmas tree light, allowing us to watch genes flick on and off in living cells.

What gene? In this case, the GFP construct lets us see whenever a gene called HSP-16.2 is turned. HSP stands for Heat Shock Protein; it's one of a class of genes that are switched on when cells are stressed by harsh environmental conditions, such as when the temperature is artificially elevated. You can also induce them with cold or oxygen deprivation or disease. Many HSPs are chaperones, or proteins that assist in the folding of other proteins—they prevent proteins from being denatured. Others assist in transporting proteins from one compartment of the cell to another, or in flagging damaged proteins for destruction.

So Rea et al. have a line of worms where they can see an HSP gene being turned on. When these newborn nematodes are examined with a microscope, nothing is glowing; the investigators then crank up the temperature in the incubator from a comfortable 20°C to an unpleasant 35°C for an hour or two, and here's what they see in the scope:

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On the left is the view with normal optics, and on the right the view with fluorescence optics, and you can see the worms are glowing greenly—as expected, they've turned on the heat shock proteins in response to a heat shock. Look carefully, though, and you'll see that there is variation. Some worms turn on HSP strongly (the one labeled "H"), others turn it on to a moderate level ("M"), and still others activate the gene to only low levels ("L", which are nearly invisible in the fluorescence image).

So far, so good, and not too surprising. The gene is turned on when expected, and there is variability, which is also quite common in biological systems. The degree of variability is a little bit surprising, since these are isogenic animals; the variability is not at all genetic, since they can be bred and there is no pattern of inheritance of the brightness.

So here is the very interesting correlation. The worms could be sorted out on the basis of their brightness after one hour of heat exposure, and then the longevity of the high, medium, and low HSP expressers was measured. The worms with a strong HSP response lived significantly longer than the ones with the low response.

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(a) Data from a typical longevity analysis shown (mean s.e.m.; high = 24.4±1.1 d, median = 18.7±1.1 d, low = 15.35±1.0 d; N = 40; P < 0.025). (d) Survival trajectories of worms used to generate the data in a. "Presort" is the measure of survivorship in a population that was not sorted into high, median, and low HSP expression, and "Preheat" is a population that was not stressed with a heat shock.

Keep in mind that HSP expression is only a marker of some general and incompletely understood processes by which the organism copes with stress; artificially increasing the quantity of HSP in a nematode does improve its life span by a small amount, but not as much as was seen here. They're just seeing one note in the symphony, which is enough to tell it is being played, but not enough to know all the players.

The fascinating thing to me is that they are finding so much significant (I think a 50% increase in average life span is certainly significant!) variation in animals that is not a consequence of heredity, but is clearly an outcome of early, random processes in development and physiology. The authors offer some explanations:

Stochastic variation arises from fundamental thermodynamic and statistical mechanical considerations. A large fraction of individual variation in lifespan must stem from the fact that life results from an integrated series of metabolic reactions that themselves are under physical constraints of the specificity and rigidity with which they, too, can be regulated. At the molecular level, two points are germane to this study. First, when the number of molecules regulating a biological process becomes countably small, chance distributions come into play such that some regulatory molecules can vary severalfold between individual cells. Second, the Maxwell-Boltzmann (M-W) equation specifies the distribution of kinetic energies among molecules and requires kinetic energy to be a distributed function. This equation was used to develop a general theory explaining mortality kinetics. Several sources of variation at the molecular level could conceivably alter GFP (HSP-16.2) expression level and simultaneously affect more global processes. These include intracellular differences and fluctuations in the rates of molecular processes such as transcription, ribosome loading and translation (as previously postulated). Chance variation in the number of HSF effecter molecules present in each cell at the time of heat shock also could have marked phenotypic consequences. Variation in the frequency of mitochondrial genomic rearrangements, as previously observed in isogenic populations of C. elegans could have an effect. There is a growing body of research describing variation among isogenic individuals at the molecular level, typically in microbial or yeast cultures where such effects can be visualized. Substantial variation among genetically identical individuals is a fact of nature, and inherent molecular variability implies that biochemical and molecular genetic processes must have inherent variability.


By the way, since I began with Bladerunner, I've got to complain about one scene in the movie. The replicant Roy confronts his maker Tyrell, and wants to know how to stop his death clock. Tyrell makes excuses.

TYRELL: The facts of life. I'll be blunt. To make an alteration in the evolvement of an organic life system, at least by men, makers or not, it fatal. A coding sequence can't be revised once it's established.

ROY: Why?

TYRELL: Because by the second day of incubation any cells that have undergone reversion mutation give rise to revertant colonies—like rats leaving a sinking ship. The ship sinks.

ROY: What about E.M.S. recombination?

TYRELL: We've already tried it—ethyl methane sulfonate is an alkylating agent and a potent mutagen—it creates a virus so lethal the subject was destroyed before we left the table.

ROY: nods grimly.

ROY: Then a repressor protein that blocks the operating cells.

TYRELL: Wouldn't obstruct replication, but it does give rise to an error in replication, so that the newly formed DNA strand carries a mutation and you're got a virus again…but all this is academic—you are made as good as we could make you.

All of that is total gobbledygook. For instance, EMS is commonly used as a mutagen, but it doesn't create viruses; the contrived rule about coding sequences being incapable of revision doesn't make sense; the stuff about repressors causing replication errors is just babble. That part of the movie always makes me cringe, because it is so clear the writer just plucked random biology words out of some textbook and strung them together in ways that make no sense.

He should have just said his lifespan was in part an ontogenetic consequence, and it couldn't be corrected short of rewinding his entire life history back to fertilization, and replaying his development. That's one of the lessons of this paper, at least.


Rea SL, Wu D, Cypser JR, Vaupel JW, Johnson TE (2005) A stress-sensitive reporter predicts longevity in isogenic populations of Caenorhabditis elegans. Nature Genetics, published online 24 July 2005.

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Couldn't have said it better. It's my favorite movie until that gush of cartoonish nonsense. It would be great to have a version in which that sequence is dubbed over with something scientifically defensible.

Gobbledy gook or not (and it is...) Blade Runneris still one of the finest films ever made. Beats the pants of Do Androids Dream of Electric Sheep IMO. The effects still look great by today's standards.

You do of course realize the Phillip K. Dick wrote that goobledygook in 1968? I don't think the scriptwriters would be in the position to correct Mr. Dick.

Anyway, like most SciFi, the technology isn't really important, it's the consequences of the technology on the people involved.

thanks,

Film (the directors cut) was better than the book. Best twist of any story, IMHO. [unicorn scene]

Also, taking a step back and looking at death from a species / evolution perspective: clearly for the process to work old generations must be cleared, unfortunatley.

Also, consider this, if you worked with test tubes and they had 5% chance per day of getting smashed.. how long would you make their 'natural life'?

Somewhere I saw an estimate of human life expectancy with all age-related causes taken out. Something like 700 years. So accidents, homicide, etc. do happen, but most deaths are linked to aging.

That part of the movie always makes me cringe

But everything else makes so much sense. LOL!

Right.

By Great White Wonder (not verified) on 09 Jan 2007 #permalink

Or in the immortal (no pun intended) words of Chuck Palahniuk: On a long enough timeline, the survival rate for everyone drops to zero.

'S funny, inserted gobbeldygook doesn't bother me as much as some people. I always just translate it in my head into what the writer meant, which in this case is basically, "Did you try the obvious things?" "Yep. Don't work." "I came up with this clever notion..." "Tried that too." and let it roll on. To link back to the real topic, writers are mortal too-- there wasn't TIME to put Phil Dick through ten years of biology, he never would have gotten the novel done.

That said, "midichlorians" do still make me want to strangle George Lucas.

However, accidents homicide etc. are far less common in modern industrial society than for hunter-gatherers. So the current life expectancy without age-related causes is not very relevant to the evolution of aging in humans.

By Jim Baerg (not verified) on 09 Jan 2007 #permalink

Substantial variation among genetically identical individuals is a fact of nature, and inherent molecular variability implies that biochemical and molecular genetic processes must have inherent variability.

Nothing new here. God may not play dice with the universe, but he definitely plays dice with Einstein's balls.

As for the "several fold" differences observed in the worms, nothing surprising there either. Bacteriologists work with clones all the time.

Surely there have been studies on traits which correlate in the twin which exits the human vagina first? Am I wrong?

And I'm not slagging on the work these researchers did. It looks like a decent study. I'm just a little bored of longevity studies in nematodes, but I understand that longevity is "sexy" and therefore it's going to get milked until the grant money dries up.

By Great White Wonder (not verified) on 09 Jan 2007 #permalink

Yeah, the crap about midichlorians make the sequence from Blade Runner look like top-notch science.

Keep in mind that exchange between Tyrell and Roy has nothing to do with Phillip Dick, it's from Hampton Fancher, who wrote this section of the screenplay. But I wouldn't be so hard on him. He claims to have written that exchange from the top of his head, no background research. And he has no scientific training.

Also another bit of science-related Blade Runner trivia..the enlargement of the "snakescale" when Deckard visits animoid row is actually a real electron microscope photo of a female cannabis plant.

Dboy

That 700 year estimate ... that's not real. It says something like that in the bible, of course... (or am I missing a joke here?)

Hey, Greg Laden, I'm commenting on a science post! :-)

I'll cut Ridley Scott and his crew some slack since Blade Runner was such a top-notch film, just like his first two (The Duellists and Alien). But really, filmmakers should do their homework if they're going to make science an important part of a film's setting or plot. War films hire retired DIs and commandos and put their actors through boot camp--why can't a science film hire 2 or 3 PhDs as technical advisors?

My friend (a computer science prof) is similarly annoyed by the portrayal of computers in films, just as I (a librarian) get irritated at how information in general is handled. Not just the arrogant Jedi librarian in Attack of the Clones, but in the late 80s/early 90s, when computers were becoming more ubiquitous, many shows and films operated under the Law of Conservation of Information. As in, if a digital file was downloaded from a database it no longer existed in the database! This notion of treating electronic files like physical documents kind of undermines one of the main reasons for the digital version in the first place.

I'd like to see PZ review Gattaca. I liked that movie, but I'd like to know what someone closer to the field has to say about it.

By False Prophet (not verified) on 09 Jan 2007 #permalink

No that 700 estimate might be real. I've seen others up to a few thousand years. They are not that hard to do - in the crudest form just figure out the chances of homicide, suicide, and accidental death per year per person - we have those statistics - and then just figure out what the average lifespan would be if they were the only causes of death. You can look at variations by age, projected trends, geography, etc to get more tricky.

I'd like to see PZ review Gattaca

I second that request. But what about The Fifth Element? That broad had 5-stranded DNA!!!

:)

I'm not sure I've quite got this -- the science part, not the movie part. (Go slow with me, please, I'm just a curious civilian....)

Do I understand the experiment properly? Take some genetically identical organisms and put them in identical environments. Change that environment identically for all the organisms, and random, inherent, variable molecular activity results in different reactions among the organisms, correlating with differences in longevity?

One implication being that random, inherent, variable molecular activity will occur "in the wild" and also result in different reactions among organisms which will also correlate with differences in longevity irrespective of the genetic similarities of organisms?

In what sense are random, inherent, variable molecular activities "in between" genetic predetermination and pure luck? (How come that isn't "pure luck?")

And by the way, how do we know that inherent variable molecular activity of this sort is not heritable?

By Jeff Chamberlain (not verified) on 09 Jan 2007 #permalink

Obviously PZ needs to write a book on bad biology so it can go on the shelf next to 'Bad Astronomy'.

By idragosani (not verified) on 09 Jan 2007 #permalink

Star Trek scriptwriters, when they come to scenes like this, simply type "TECH", short for, "Insert technobabble here", meaning, "Hey, science consultant, go look up some [botany] [physics] [medicine] stuff I can use in this scene."

I wish scriptwriters would be a little more conscientious about their use of technobabble. I remember one sterling example of Getting It Right, in some cutesy forest-fairies cartoon, where the wise old mole physician sent our heroes to find herbs for a pesticide-exposed butterfly (or something like that), and rattled off a list which I recognized as being things (Eye Bright, liverwort) that an herbalist would indeed give to a poisoned person.

The Fifth Element? Boron, The Movie? It was so bad it needs robot shadow puppets making fun of it!

A close look at the graph may reveal further heterogeneity. Note that the high mortality (low hsp response) group drops quickly over the first 15 or so days. Those that are still alive at that time have the same expected maximum life span and half life from then on as the low mortality, high hsp group.

On the same lines, what is up with the Preheat group? They have a low mortality early on and then high mortality from ~6-15 days, then level off with the low expressors.

Given the differences between most of the heat shocked animals and the Preheat, is it possible that a key mortality difference is the immediate consequences of the heat shock and the sequelae before day 10? Or the coupling of that to notable increase in mid-life survival of the greens as a consequence of having been heat shocked? In other words, maybe the heat shock response induced by heat shock, is indeed what extends life (compare presort to preheat), not a marker of life extending goodness in the absence of heat shock.

By MIke McKeown (not verified) on 09 Jan 2007 #permalink

I love Fifth Element because it doesn't even pretend that the science makes sense. I mean, the point where the big alien spaceship stops at a row of traffic lights in space should really be a hint that it's the kind of movie where spaceships travel at the speed of plot. We can all relax and watch the pretty lights.

By Stephen Wells (not verified) on 09 Jan 2007 #permalink

The only part I liked in The Fifth Element was the opera scene. There is something titillating about the idea of intelligent beings from outer space appreciating Earth's great geniuses (artists and composers). I know Carl Sagan thought about it -- he even sent some Bach into outer space.

BTW, the opera singer character's name was Plavalaguna -- what a great name for a blog!

Bruce Willis' worst movie?

Thankfully, I have no idea how such determinations are made.

Maybe in the next thread we can discuss Rachel Ray's worst recipe.

By Great White Wonder (not verified) on 09 Jan 2007 #permalink

Markk:No that 700 estimate might be real. I've seen others up to a few thousand years. They are not that hard to do - in the crudest form just figure out the chances of homicide,

There are two kinds of animals (by one way of reckoning) Those with determinant lifespans and those with indeterminate lifespans. (This is an oversimplification but but will get us to a place way more correct than thinking that if nothing bad happens to you you will live for several centuries, so please bear with me).

Animals with indeterminate lifespans have to get run over by a bus to die. (or eaten by a shark, or whatever). They may even grow continuously throughout life, but often very very slowly (most animals, by count, do not grow throughout life, I think ... certainly not most vertebrates).

Animals with determinant lifespans literally age. They don't get older just because they get crapped on by stuff that happens, but they actually undergo a series of changes that usher them from one stage of life to another, with the final stage being some sort of old age which generally and eventually leads to death.

All mammals have determinant lifespans. If any verts have indeterminate lifespans it would be among the reptiles (maybe amphibians, but I highly doubt that).

There can be a huge difference in some species between typical lifespan under "normal" (i.e. wild) conditions and highly protected conditions. Animals that live in the wild for an average of 5 years with a typical maximum of 8 or so may be found to live in zoos for 10 or 20 years. A doubling or tripling of total lifespan happens, but is not typical.

Among certain clades of verts, there are interesting variations in life history that have to do with aging. For instance, the opposum (there are several species) generally has a short life span. Here's why: Opposums are so easily preyed on (and cant hibernate) that in some populations the chance of a male living through to a second breeding season is so close to zero that there it might as well be zero. Therefore, the distribution of energetics across the 'possom's lifespan is such that the males mate, then shortly after get old and die. Most actually die of old age at about a year or so, depending on the species or population, if they are not first killed by someting. One island population on the Atlantic coast (And I can't think for the life of me of the species name ... but I'm pretty sure it's got one. A google search for "Carolina Possum" leads mostly to recipes) Anyway, males in this island group/species have the shortest lifespan for body size of any mammal. They are born,grow up, mate (hopefully) and by the time any other mammal would have finished the first post-coital cigarette, they are dead of old age. (only slightly exaggerating here ... they live a total of just a few months)

(This is primarily true of North American possums, but in general this clade lives to aobut 80% of the average lifespan of non-arboreal terrestrial eutherians)

Anyway, that is the general pattern. Mammals age. Extending lifespan is not just staying away from the bus stop and eating a lot of antioxidants (though perhaps both can help), but it would involve changing life history events that are as inevitable as, say, puberty.

We are all anxiously waiting to see what happens to Michale Jackson. Who, by the way, was born on the same exact day as me. So maybe I'm the control...

While higher HSP expression was associated with lengthened lifespans under those particular conditions, there are also costs to heat shock protein activation and associated processes. For example, heat shock proteins are implicated in some forms of autoimmunity in mammals.

Whether developmental differences (including HSP expression or even propensity for such due to underlying processes) resulting from chance are advantageous or detrimental is often dependent on environmental context. These environments are not entirely predictable, hence chance differences are another form of variability that can enhance the fitness of at least some individuals within even a genetically identical cohort.

We are all anxiously waiting to see what happens to Michale Jackson. Who, by the way, was born on the same exact day as me. So maybe I'm the control...

That gives a whole new meaning to the phrase 'Weird Science' ...

Is cool that you posted this today. I just watched an episode of Nova Science Now which discussed long-lived humans and how high HDL levels AND a very low calory diet (around 1500) + red wine consumption contribute to longer lives. Work on Surtuins is showing promise in everything from those c. elegans to laboratory mice as well.

The link is to NPR's podcast of the show, though I think it's a little more brief than the TV epi I just watched. Is worth a listen, or catch the show if you get the chance.

Personally, I'm working on wanting to live more Now, but I know it's worth it, and already have about a 1700 cal diet, though w/ too much fat, and have recently started on a glass of Shiraz a day. Put all that together (and I quit smoking!!!!!!!) and I could still have an entire normal length life-time to enjoy beyond my 41 years to date.

My point being, and thanks for your incidental but perfectly timed reminder, PZ, it's never too late to get your shit together and enjoy a long life!

Cool. Now this is the sort of reading material I come to Pharyngula to browse through.

In comment to the article itself: does this mean the post-genalyptic world of Gattaca and the social concerns about designer babies is on its way to being busted as the fever dreams of genetic-tampering-scare-Nazis?

Because it doesn't matter if you play with your kid's genes in the womb, there is going to be variation from the desired order as a result of factors we do not fully understand?

(And yes, I totally made up the word "post-genalyptic".)

already have about a 1700 cal diet, though w/ too much fat, and have recently started on a glass of Shiraz a day.

Three or four glasses is ideal, as long as you don't have to get up too early for work. ;)

By Great White Wonder (not verified) on 09 Jan 2007 #permalink

"Chris Rock's best movie."

You mean Chris Tucker?

No, Rey Fox, I think he means Chris Rock. Any movie he's not in is his best movie.

does this mean the post-genalyptic world of Gattaca and the social concerns about designer babies is on its way to being busted as the fever dreams of genetic-tampering-scare-Nazis?

No, because the eugenics/discrimination in Gattaca is not the result of government policies, it's entirely market driven.

Also, the "valids" in Gattaca were not exactly "engineered" (in the GMO sense)... nothing was changed in their genes.

The science in Gattaca is pretty sound, and the movie doesn't lean on it too hard. It's a smart, complex flick ... which would explain why it did so poorly at the box office.

And Bruce Willis' worst movie is Armageddon, in the sense that it was one of the worst movies ever made, and Bruce Willis was in it.

I wasn't actually talking about the social situation in Gattaca, but the background idea it contained: being able to create designer "superhumans" without failure (and the associated real-world movement that reacts with fear and horror to the idea of designer babies who will necessarily be everything their parents want).

Probably a poor choice of example, since the movie is all about how you can't bank on our understanding of genetics to know what we will be.

And I agree, Gattaca was a wonderful movie.

So, this thread happened because everyone wants to falsify Greg Laden's analysis of the other day re comment volume vs. post topic, right? ;-)

Oh, and another vote for Gattaca as a great movie.

By Steve Watson (not verified) on 09 Jan 2007 #permalink

False: Hey, Greg Laden, I'm commenting on a science post! :-)
...

I'd like to see PZ review Gattaca. I liked that movie, but I'd like to know what someone closer to the field has to say about it.

Great job commenting on the science post!

At least some things have improved in movies, esp. with Spielberg and certain other directors: The scientists are not total nerds as often. Sometimes they are even sexy leading men and women (perhaps they have gone too far).

I also like Gattaca. My wife uses it in her HS bio class (one scene edited out).

I have only seen it once, and not really from beginning to end (I'm the guy who edited out that scene). They seem to totally disguise the science. Imagine knowing only about Eniac and having to predict the early 21st century world of computers. Hiding the technology in Sci Fi is probably a good idea..

12 Monkeys.

That's an interesting contrast to Michael R. Rose's findings with his Methuselah flies; the ones bred by simply not allowing reproduction at an early age to be successful (discarding eggs of early matings, for example). He found some similar things: stress survivability seemed to go hand in hand with longer life.

Also, getting neutered seems to help individual lifespan, in particular when you're a fly with a great deal of your body dedicated to reproducing. Castrati in humans apparently enjoy longer lives. Probably more extreme than one would really be willing to put up with :)

His hypothesis was that natural selection pressure is at its maximum up to reproductive age, and dwindles to extremely low after the reproductive window, and that generally ends up being the case.

His main point of optimism was that, even in humans, there isn't actually such thing as a 100% mortality rate due to age. Mortality rises from a minimum to a maximum that mostly plateaus. Now mind you, the maximum is still fairly high, but his point was that you do not have to stare down an infinite wall to make dents with anti-aging research.

One surprise to me from his book, The Long Tomorrow (I review it here), is that there seems to be very little interest in anti-aging research. Who wouldn't like many more years? Apparently, lots of people. They can't all be accounted for by those who have spent too much time with snake oil. Either that, or they have spent too much time already believing in snake oil :)

Jim Morrison said it best, "no one here gets out alive."

No that 700 estimate might be real. I've seen others up to a few thousand years.

It is about 1-2000 years in industrial countries.

When you look at mortality rates in humans, you find a curve similar to the reliability "bathtub" (U)curve for most engineered systems. For pretty much the same reasons you see decreasing early failure rate, followed by a low nearly constant failure rate, followed by increasing wear-out failures.

So you simply use the lowest insurance mortality at the nearly constant rate, 1-2/(1000*year) deaths @ 20 years, to predict life expectancy.

That said, "midichlorians" do still make me want to strangle George Lucas.

I can't understand the need for some to convert space opera with fantasy and/or religious parts into hard scifi. David Brin is another writer who can't resist explain such plot devices (magic like entropy reversal in "The Practice Effect" fantasy) with "scientifiness". It looks completely misplaced.

By Torbjörn Larsson (not verified) on 09 Jan 2007 #permalink

"to predict life expectancy" - to predict possible life expectancy without aging or early defects.

By Torbjörn Larsson (not verified) on 09 Jan 2007 #permalink

Hey, fact fans. The Roy Batty lines ("I've seen things you people wouldn't believe...") in the OP were improvised by Rutger Hauer.

700 sounds low to me.

in the crudest form just figure out the chances of homicide, suicide, and accidental death per year per person - we have those statistics - and then just figure out what the average lifespan would be if they were the only causes of death. You can look at variations by age

Well the death rate from accidents etc is a function of the life span isn't it? If society expected you to live longer then it wouldn't accept you taking so many risks. Also most of the homicide, suicide and accidental deaths are grouped around the 20's.

By DavidByron (not verified) on 10 Jan 2007 #permalink

Thanks for bringing this paper to my attention. It highlites the fact that noise is an integral part of biological systems, and has real physiological consequences. Of course, this shouldn't come as much of a surprise to the seasoned biologist. Perhaps if more of the general public understood these results, then there wouldn't be so many people under the misconception that someone could clone Hitler and start a new holocaust.

Stupid question: is having a strong expression of the stress proteins a trait that remains constant for an organism (so that if you stress them again, the proteins are expressed as much as they were before)?

Because the explanation presented, while otherwise quite acceptable, fails to make this clear. If it's not - and the worms that expressed it a great deal just happened to express it this one time - then possibly the mortality implications are entirely a consequence of how much the thermal stress damaged the worms in that single exposure, with the long-lived worms just being the ones that managed to put up an effective response to the single stressor.

By Caledonian (not verified) on 10 Jan 2007 #permalink

"We made you as good as we could" refers to the fact that Roy Batty was made by Tyrell for a certain purpose, and he is as good as they could make him in relation to that purpose. The dialogue is a tragic, in the original Greek theater sense, since all has been already decided and what we are seeing and what they are doing is the inevitable unfolding of that tragedy. The poignancy and force of the dialogue of the film, indeed) comes from the tacit understanding that we, human beings, have been too formed, polished, designed (not by Tyrell but by mindless, natural evolutionary forces) to be what we are, and we too carry a self-destruct death mechanism. That molecular mechanism makes sure that we do not overstay for too long after reproduction.

Now, Roy Batty as well Tyrell know that this is the situation and it is futile to try to change Batty's programming. Even if it could be done, Tyrell will not do so, probably because it would violate the terms of the licence withing his corporation is operating. I always interpreted that dialogue as Tyrell trying to shake off Roy with some meaningless nonsense, hoping that Roy will accept his destiny and go away. Roy may feel that that is the situation, and powerless to change it, kills Tyrell. The assessination of Tyrell by Roy is a protest, an act of vengeance. May be I am reading too much into that short dialogue, but the message may be that Tyrell has sinned and duely punished. The sin being ... what? I dont know. The notion of sin is valid only in an universe with a God, and there is none around. (Roy killing Tyrell is, in my opinion, senseless, unjust and I never liked it).

I want also to comment that the European Union is legislating more and more regulations that require the manufacturer take responsability for the disposal of its product. Computer makers have to take back used computers, and automakers will be forced to take back used cars and dispose it according the strict rules of the Union. If this tendency developes, as I think it may, then designers of new products will have to include self-destruct mechanisms, and also self-degrade mechanisms. Death and decomposition, in a word. In the future, the dialogue between Roy and Tyrell may become true, but most probably Roy will not look like a beautiful human being.

...and we too carry a self-destruct death mechanism. That molecular mechanism makes sure that we do not overstay for too long after reproduction.

Sorry, a bit too teleological for me. There are no molecular mechanisms that prevent us from living a long time, there are only mechanisms to ensure that we live long enough to reproduce as much as possible (and in some species provide care for offspring and kin). Those are the only kind natural selection can see.

After that, selection is through with us, and the rest, as they say, is gravy...at least until cumulative oxidative stress, bad luck, or late onset phenotypes kick our asses.

miko: Are you sure there are no molecular mechanism that prevent us from living a long time? I am not sure. probably there are many operating to that mortal effect. Anyway, cumulative oxidative stress you mention (?) and statistical bad luck have the same effect. Moreover, even if it is unpolite and un-PC, when old farmers insisted in keeping farming and caring for their grown up or middle-aged children, they were usually helped to step down (sic!) as Presidents of the Board of family firms. The gravy you mention is normally consumed by the next generation, as it should be. One more interesting observation (in my family at least), old people, when feel that they are not contributing anymore or need attention from younger members, seek death voluntarily. Like in the Death of a Salesman, he arranges his death so that the family will enjoy the insurance. I believe that that kind of behaviour (like others) has its molecular basis.

Jim Lund: I understand (having never seen the movie) that the fifth element in this case is the fifth Aristotlean element, i.e., the divine element, ether/aither.

This is of some relevance to the thread, since if ether really were incorruptable, perfect, etc. ...

No that 700 estimate might be real. I've seen others up to a few thousand years.

It is about 1-2000 years in industrial countries.

When you look at mortality rates in humans, you find a curve similar to the reliability "bathtub" (U)curve for most engineered systems. For pretty much the same reasons you see decreasing early failure rate, followed by a low nearly constant failure rate, followed by increasing wear-out failures.

So you simply use the lowest insurance mortality at the nearly constant rate, 1-2/(1000*year) deaths @ 20 years, to predict life expectancy.

That said, "midichlorians" do still make me want to strangle George Lucas.

I can't understand the need for some to convert space opera with fantasy and/or religious parts into hard scifi. David Brin is another writer who can't resist explain such plot devices (magic like entropy reversal in "The Practice Effect" fantasy) with "scientifiness". It looks completely misplaced.

By Torbjörn Larsson (not verified) on 09 Jan 2007 #permalink

"to predict life expectancy" - to predict possible life expectancy without aging or early defects.

By Torbjörn Larsson (not verified) on 09 Jan 2007 #permalink