Risky Business

Who is so dense as to maintain…that all their witchcraft and injuries are phantastic and imaginary, when the contrary is evident to the senses of everybody?

—Malleus Maleficarum, 1487

There is a really excellent paper on risk called Witches, Floods and Wonder Drugs:  Historical Perspectives on Risk Management (pdf) by William C. Clark.  It was written some time ago (1980) but is still highly entertaining and edifying.

In the "witches" part of the paper, Clark discusses how, prior to the 15^th century, being a witch was considered a privatized risk:  "Well, if she wants to skip church, talk to her cats and read chicken entrails, it's her own immortal soul on the line."  It was punishable by, perhaps, a day in the stocks.  With the publication of Malleus Maleficarum (The Hammer of Witches) in 1487, witches became a socialized risk. Witches were responsible for crop failures, bad weather and high crime rates.  Witches were everybody's problem. 

Clark discusses the “stopping rule.”  During the Inquisition, their was only two possible outcomes of an interrogation.  Either the hapless victim confessed and was a witch, or she hadn’t yet confessed.  Guilt could be proven, but not innocence.  If the rack and other engines of torture were applied long enough, it was only a matter of time before confession. There was no “stopping rule.”  Thus, since almost everyone interrogated turned out to be a witch, witches proliferated as did the ruthless arm of the church responsible for hunting them down.

We see the same approach being used today. Torture the data long enough and it'll confess to anything.  It doesn't matter what the chemical, contaminant or drug is, given enough tests eventually some harm will be found.  And even if no harm is found, that doesn't mean it's "safe."  It just means that they haven't found the harm yet.  There's no stopping rule.

The science of risk has exploded: risk assessment, risk management, risk reduction, risk communication.  Risk assessments for sites contaminated with industrial chemicals easily reach thousands of pages.  We tests massive doses of chemicals on animals to infer effects of minuscule doses to human beings.

Environmental impact assessments that are required for new projects such as mines and oil pipelines are supposed to be, in essence, a quantification of risk.  Yet they've morphed into unwieldy behemoths that run for years, have a cast of thousands and cost millions. 

And yet, at the end of it all, the scientific risk, the quantitative risk, is not really what matters.  What matters is the perception of risk by people. 

Marijuana is a good example.  Here is a drug that has been widely used in the west for over fifty years, and in the east for eons, to little overall effect.   Every major study ever conducted on pot has more or less concluded that its use is overwhelmingly a personal risk and not a social one. People don't die from it and they don't kill for it. 

The problem that prohibitionists have with marijuana is a moral one, not a technical one.  Recreational use of a mind altering-substance is abuse.  It's immoral.  It's not good.  But immorality, like witchcraft is a privatized risk, and so, to force action by the state, they have to socialize it.  They have to make it everybody's problem.  They need to blow the risk vastly out of proportion.  Now who would be good at doing that?  Oh, I know—cue the media.  Next thing you know, Walt the postman is getting random urine inspections, and we have an entire industry of professionals whose job it is to watch you pee in a cup.

At one point, if you were dumb enough not to wear a seat belt, then that was social Darwinism at work.  That risk was socialized.  Crime.  Despite ample evidence that violent crime is decreasing and has been for centuries, we have to build a bunch of new prisons in Canada.  And the US, with 5% of the world's population, has 25% of the world's incarcerated population. 

Helmets.  Diving boards.  Alcohol.  Butter.  Trans-fats.  Second-hand smoke. Terrorists.  Carbon dioxide. Saccharine.   And those are just the risks we know about.  With all these deadly risks, most of them unknown to us a generation ago, how is it that we manage to worry our way to a historically high life expectancy of 85 years? 

Kaboom Kabul

You know what's weird.  Watching mortars go off and listening to gunfire in some far off country on CNN, and realizing that you're sitting right in the middle of it all.  Insurgents launched a coordinated attack against a number of targets in Kabul, including NATO headquarters, where I am, to kick off the spring fighting season.  Mostly small arms fire RPGs (rocket-propelled grenades) and mortars.  Heck, in Kandahar province that would barely rate stopping a gym workout.  It must have been a slow news day, or the middle of the night back home, because there was lots of coverage on CNN, an BBC and Al-Jazeera.  I don't know how many times I've seen similar footage in Lebanon, Libya, Syria, Palestine, Iraq.  But this time it was like "Hey, there's the market I go to."

CNN was pretty breathless about the whole thing.  You'd think the Taliban had taken Kabul.  But from a military perspective, it was an abysmal effort.  The objective of the mission wasn't really military though.  The insurgents—including primarily the Taliban and the Haqqani network—are basically trying to carry off "spectacular attacks" in Kabul as a propaganda tool.  It's to try to convince people that they are more effective than they actually are, and to degrade the Afghan people's tenuous notion of stability. 

Afghan security forces dealt with the attack and ISAF (NATO) quick reaction forces were not needed.

A big thank you to all those who contacted me to see if I was OK. 

A couple of days earlier myself and a couple of friends were wandering down Chicken Street and Flower Street—the main shopping district in downtown Kabul, and what used to be a tourist hub.  It was  a nice day and I thought there'd be lots of folks perhaps from the embassies and the various non-governmental organizations doing the tourist thing, but we were the only ones.  I think a lot of the Afghans were kind of shocked to see us moseying about actually.  They just stared at us.  Except the kids. We had a gaggle of them dancing around us half the time. 

Anyways, I managed to snap off a couple of shots, but they are quite leery of cameras here.   I put it away after an Afghan soldier got a little irate with me, and counted myself lucky to still have a  camera. 

Chicken Street, Downtown Kabul

Chicken Street Again. 

At the Kabul Bookstore.

Typical "subdivision" in Kabul.

Only a month to go to R&R back in Canada, in mid-May, so I'm looking forward immensely to seeing my family, playing some soccer, and having a beer or three with my mates.  Counting the days.

What if You've Never Made a Decision

Do I dare
Disturb the universe?

T.S. Eliot—The Love Song of J. Alfred Prufrock

If you choose not to decide

You still have made a choice.

Neil Peart (Rush)—Free Will

What if you've never made a decision?

That's the conclusion of Sam Harris in his book Free Will. 

Free will—the idea that we can make decisions about what we will do—has always had its philosophical problems. 

For instance, in Christianity, the entire edifice of sin is based upon the idea that we, as humans, have the capability to choose between right and wrong.  But, the Judeo-Christian God is also omniscient.  He knows how everything will turn out.  So how can we truly have free will if God already knows what we are going to choose?  Is our choice not then preordained?  There's no easy answer, and more than one Jesuit was locked up in the medieval equivalent of a cubicle trying to circle that square, let me tell you.

Things didn't get much better when Galileo and Newton came along.   According to science, up to the 20^th century, the universe was mechanistic, deterministic, unfolding like clockwork to its ultimate end.  If you knew, in theory, where every single particle was and where it was going at this instant of time, the entire future would be known to you.  So where is the free will in that?

The turn of the century saw the advent of quantum physics.  Reality was no longer deterministic.  Subatomic particles existed as probability functions—the electron could be here, or it could be over there.  When observed, the probability wave function collapsed.  One probability became equal to 1 (i.e. it happened) and all the others went to 0 (and didn't happen).  There was no way to know for certain, even in theory, which event would transpire.  So now the course of the universe was based on the roll of dice, on mere accident.  There's still no room for free will.

Compound this with some recent studies in brain science indicating that people who think they are exercising free will, have in fact, already made up their mind about issues long before they think they have made a decision, and you can see that the entire concept of free will is on some pretty shaky ground.  We're just a bunch of meat puppets.

This indeed is Harris's conclusion.  Now I admit to a bias up front.  Harris is a founder of this outfit that is called Project Reason that seeks to spread "secular values" in society.   This secular evangelism is just as annoying as Christian evangelism.  More so.  At least the Christians offer everlasting life in Paradise. The secular crowd: You are so incredibly insignificant that words in the English language cannot adequately convey how much you don't matter.  

Not only that the secular evangelist books God is Not Great and The God Delusion, which I've read, we're both, in my opinion, abysmal.  They didn't make their case.  And I'm  Scientist and an Agnostic—I should be an easy sell.

The problem, for me, is that Harris is trying to take science, which is  a useful tool to logically extend our senses to observe and predict nature, and turn it into a value-based philosophy.  But reason itself, as I've explained in the past, is a solid stone castle built in mid-air, held aloft by—you guessed it—faith.  Besides which, science is concerned with what is, not what should be.

Anyways, probably because of that, I was a little more critical of the book than I normally would have been.

We all imagine that we—our "selves"—exist, parked on top of our bodies, peering out through our eyes and instructing the machine we inhabit to make us a cup of tea or whatever, like the drivers of those big Imperial Walkers in Star Wars.

Cup of tea, then?

According to Harris, we may be in the vehicle, but we ain't drivin'.  You did not decide to have Weetabix instead of Corn Flakes this morning.  Your brain chemicals did that.   And even if you decided  that you were going to show those brain chemicals who's boss and go for the Corn Flakes, dammit, it's no good, because your brain chemicals already determined that before you did.

I can certainly go along for the ride and allow for the possibility that free will is an illusion.  After all, why should I think that I can change the course of the universe with but a thought, but a rock can't.  But If I'm going to buy that free will is an illusion, I insist that Harris takes the argument to its logical extent.

The notion that we have free will is intricately woven into our idea of self, of ego, of that feeling of continuity you have that you are you.  Harris takes this vital component of the self—will—and says that it is illusory, but that what is left of the self is still real.  Nonsense.  If free will is an illusion due to a bunch of brain chemicals burbling up to the "conscious mind," then so is the ego, your entire sense of self.  It's all burbling chmcials and dancing neurons.  The self is an epiphenomena induced by trillions of cells working symbiotically. The ego is an emergent property of a complex system.  A "transient landscape of the mind" as David Hume called it. 

So the knowledge that self and free will are an illusion doesn't really get us that far—unless you're a Zen Buddhist, in which case you can consider yourself Enlightened.  Just because you are convinced something is an illusion doesn’t mean it can be dispelled.  Ask a schizophrenic.  Ask a guy whose right foot hurts, even though he lost that foot five years ago.

The self—including the notion of free will—is an illusion that it is simply too difficult, and perhaps too valuable, not to maintain.   


And what is the difference between reality and an illusion that cannot be dispelled, especially when that illusion is being imagined by your self, an illusion?  OK, I just threw that one in to screw you guys up.

Immortality and Cancer

So what if we could just program our cells to be immortal?  after all, that little jellyfish I talked about earlier can manage it.  And they've managed to reverse aging in mice.  And if old age in cells leads to old age in people, then immortality in cells leads to...

Ah, be careful what you wish for.  There are already two kinds of immortal human cells I know of.  One is stem cells (and the jury is out on this, I believe).  Stem cells are cells that have not yet differentiated; have not yet found their purpose in life to see the world and be a retinal cell,  or perhaps help out a bit in the kidneys.  They are common in embryos.  Anyways, we're not here to talk about stem cells.

The other type of immortal cell is a cancer cell.  Cancer is a multifaceted disease of diabolical  sophistication, but all cancers rely on one thing:  a cell somewhere has being given the signal to perpetually divide. 

Most cells in your body don't reproduce, although all have the potential to.  Skin cells reproduce, as do red blood cells, and others.  But for the vast majority, part of the deal of living in a multicellular organism like people is ixnay on the cell division.

Normal human cells will divide about, I think, 50 times and then die of old age.  But not a cancer cell. They go on and on and on.

As a matter of fact one woman, let's call her Mrs. Tibbets, died of a particularly virulent form of cancer years ago.  Researchers were particularly interested in her cells, so they have kept her cell line going for decades in laboratories the world over.  In a way, you could say Mrs. Tibbets is still alive, as a 50 ton tumour dispersed throughout the globe.  Her DNA, albeit with a cancer mutation, is still alive in each of those cells.

So maybe this cell immortality ain't all it's cracked up to be. 

Cancer overcomes the "natural" aging limits on a cell, the genetic programming that leads to cell old age, or senescence.  A lot of things have to go wrong for you to get cancer.  First of all you have to get a mutation in your DNA which instructs the cell to just keep dividing over and over again.  Second of all, the cell's elaborate defence mechanisms that fix mutations or otherwise prevent rampant cell division have to be rendered inert.  And third of all, an obscure little enzyme called telomerase, active when you were an embryo and your cells were dividing like crazy, has to be manufactured by the cell again.  If I understand the theory correctly, anyway.

Telomers are little caps on the end of your chromosomes (DNA villages, if you will) that act as an internal clock for your cell.  Each time the cell divides a little bit is shaved off the cap, and when it is gone your chromosomes start sticking to everything and to each other, all hell breaks loose and the cell dies.  Telomerase creates more telomers, so that the cell can keep dividing without limit. 

A mutation may cause your cell to get, or to think that it is getting, growth signals to divide.  What is supposed to happen is that, when excessive or unscheduled cell reproduction is detected, tumour suppressing proteins like p53, the sentinel, shunt the cell to premature senescence and put a right stop to that.  But if something goes wrong with the gene that make p53 then that defence may be rendered ineffective.  And not just p53; in cancer a host of tumour suppressing genes must be stopped.  Even if the mutation is allowed to drive cell growth, there is still the cell clock—telomers—that will kill the cell after a certain amount of cell divisions.  Unless another mutation has instructed the cell, after all these years, to start manufacturing telomerase again.

Slim chance right?  Well, as stated last time, your average cell DNA probably gets hit by various things that can cause mutations tens of thousands of times a day.  You've got somewhere between ten and a hundred trillion cells.  Do the math.

So, having defeated this elaborate mechanism the cell is free to divide at will which it does.  It has become immortal.  Theoretically anyway.  In reality, of course, it winds up killing the host organism and dies with it.  (Except for Mrs. Tibbetts's tumour, which is still going strong.)

The interesting thing is that this p53 tumour-suppressing gene is believed to have a directing role in cell old age.  When p53 suspects something is wrong it pushes the cell towards old age, as a defence against out-of-control cell division.  From an evolutionary perspective, this is understandable—you don't want sub-standard cells dividing.  Just like old people, old cells have a hard time being active and reproducing.  Over time your DNA accumulate mutations—ones that may not necessarily cause cancer, but mutations nonetheless—and it's thought that perhaps these tumour-suppressing proteins like p53 initiate the old age program.  They prevent the cell from dividing, and perhaps (for cells that don't reproduce) from even from repairing itself properly.  So the cells don't work as well as they should and the overall affect on the body is old age.

From this point of view, aging itself can be seen as a defence mechanism against early cancer.  The tumour-suppression genes are great early on at preventing cancer.  Without them cancer would be very much more prevalent in younger people than it is.  But as the DNA accumulates random damage over time, the tumour-suppessing proteins detect this and institute the genetic senescence program.

Given that aging and cancer may be competing interests, it looks like my hopes of an immortality pill are slim.  I might get cellular immortality, but I'd be ripped apart by tumours soon after.

On the other hand, this is all theory.  Some researchers think that there are programmed "senescence effector" genes that actively initiate aging upon reproductive maturity.  Maybe it's just turning those cells off. 

As for immortality, dammit, if a jellyfish can do it, why can't I?


Incidentally, I should give a nod to William R. Clark's excellent text A Means to an End: The Biological Basis of Aging and Death, which was my primarily resource for this series.

Aging Part 2: How People Rust

The more you complain, the longer God lets you live.

     —Old Proverb

This is the middle part of three posts on the science of aging and immortality. Like most middle parts, it's really boring.  If I were you I wouldn’t even waste my time reading it.

Still here?  More fool you.

Back in the early days, about three billion years ago or so, photosynthesis was all the rage.  This is where plant cells would create energy by converting carbon dioxide in the atmosphere into oxygen.  Oxygen, previously  trace element, started to accumulate up to its present concentration of just under 20%.  So the theory goes anyway.

Now most people get a nice feeling when they think about oxygen, probably in no small part due to the fact that they'd be dead in a few minutes without it.  But oxygen is actually an extremely corrosive substance.  Fire, for example, is simply a runaway oxidation reaction (organic carbon à carbon dioxide).  Rust—estimated to cost the economy US$2.2 trillion or 3% of the global GDP—is also oxidation.  Spoiled food—yup, oxygen.

Vigorous oxidation reaction.

 Eukaryotes (remember, cells with a nucleus are called eukaryotes; and cells without, like bacteria, are prokaryotes) didn't much care for this corrosive substance accumulating in the atmosphere.  So they made a deal with some little bacteria.  The bacteria were like, "Hey dude, let me  live here in your big cozy cell and I'll deal with that oxygen problem you got,  plus I'll pay rent in energy."  And the eukaryote cell was like "Awesome!  Stay as long as you like."  And the bacteria did. For the last few billion years.

Those bacteria, called mitochondria, are still there, in every single cell of the trillions of cells in your body. Not just human bodies, but every cell in a dog's body and every cell in every flea that lives on the dog.  They are not part of "you"; they contain their own DNA.  (Actually, because mitochondria DNA passes on to the child from the mother only, apparently we can trace every human alive back to one woman—the Mitochondrial Eve—who lived about 200,000 years ago.  But that's a blog post for another day.)

The mitochondria are the furnaces of the cell, burning (oxidizing) food to create energy.  But like all furnaces, there's issue with leakage and problems with stuff that doesn’t get completely burned.  Sometimes they form highly reactive chemical intermediaries called free radicals, which, like political radicals, are unstable and wander about basically looking to start trouble.  These radicals can mutate the DNA either the mitochondria or, uncommonly, of the parent cell itself ("your" DNA).  It's believed the DNA mutations caused by this (called oxidative stress) contribute to cell senescence (old age).  In a way, we rust.

Problem is, it doesn't explain why dogs, who basically share 80% of our DNA, burn through seven years for every one we do.  Or why a flea, which still has about 60% shared DNA with humans (scary, isn't it?) die within weeks.  It doesn't make much sense, given the similar cell mechanics and biology, that humans live a hundred times longer than a flea, or thirty times longer than mice, or seven times as long as a dog.  With such similar cell genetic characteristics, why don’t all species have similar wear and tear and therefore similar life spans?

Nobody really knows why as far as I can tell.  A prevailing theory is that, because humans reproduce when we are relatively old compared to, say, fruit flies, and because we spend a long time rearing our young, our cells have developed more complicated mechanisms to prevent or repair cell mutations caused by oxidative stress, ultraviolet light, radiation, viruses and just-plain intracellular cock-ups where one of the proteins screwed up on the Friday afternoon shift and created a mutant. 

Evolution would breed out mutations that kill us before we reproduce (that gene line would abruptly end), but mutations that kill us after we reproduce will not be "bred out" by evolution?  Let's say you're a car.  It's not like your genes are taking it in for preventive maintenance to get a good resale value.  No, if you're a car, your genes are like "Get this thing to Vegas, then who gives a rat's ass what happens to it."

Your body, according to your genes.

When you are young, your cells are good at dealing with mutations.  One protein, for example, p53, is a real Horatius at the Bridge against mutant-causing agents.  If it detects damage to the DNA it slows down the cell cycle until it can be repaired.  If the damage to the DNA is severe, it even initiates cell suicide.  Later in life, as cell mutations accumulate over time, and poor old p53 is a lot busier and starts to build up in the cell, inhibiting the cell cycle and shunting the cell to senescence, or old age.

p53 protein (white), a guardian of the cell, attached to DNA (green and blue)

So the courageous "Thou Shall Not Pass!" p53 protein and others like it, that protect the DNA early on eventually lead to cell senescence and death.  So the theory goes, anyway.

Interestingly, there is one way to lengthen life span significantly—at last in lab animals.  Calorific restriction.  Animals that get all the nutrition they need, but have their calorie intake reduced by about 40% live 50 to 80% longer than normal, and live active lives.  Calorie restricted primates have a slightly lower core temperature than others, leading to speculation that a less active metabolism slows down the bodies aging mechanisms.  So if you eat nothing but a little bit of green beans and tofu every day, you may indeed live significantly longer.  Even if you don't, it'll certainly seem that way.

So, cell senescence may be due to an intracellular "autoimmune response," if you will, as a result of DNA mutations that naturally accumulate over time.  Considering that your average DNA gets hit by mutagens tens of thousands times a day, and multiply that by a hundred trillion cells or so in your body, you can see how they'd add up.  But eventually the mechanism designed to repair such damage shunts the cell to a senescent state.  What if there were a way to fool the cell into thinking it was still young?  What if you could make the cell immortal?

Next up:  The exciting finale—Immortality and Cancer

Sex and Death (and Immortal Jellyfish and Mind Control Parasites)

Everybody has got to die, but I have always believed an exception would be made in my case.

     —writer William Saroyan's last words

It's my birthday today.  Yay.  I'm 47.  Nothing really special about 47.  It's prime, and I won't be a prime number again until I'm 53.  That's about it.  Now that I'm getting on a bit I've become suddenly intensely interested in aging. 

We all get old.  We all die.  Now dying sucks for two reasons.  First of all, it's painful. And second of all, at least as far as science goes (which isn’t that far),  when you die you never come back again.  The molecules of which you were presently comprised are still lying there, but you, the ghost in the machine, are forever gone from this time and place.

When you examine the biological basis of aging, as we will over the course of  the next blog post or two, one of the things that you will find striking is the close relationship of aging to cancer.  It's in vogue now to be really mad at cancer.   To rail at it.  To hate it.  To treat it as an enemy.  You don't "have" cancer; you "battle" cancer.  You see t-shirts emblazoned with "F%$K CANCER."

You tell 'em, Sarah!

And yet we don't have the same attitude about aging.  Heck, we even tut-tut those who refuse to "grow old gracefully."  Nobody gets mad that they are dying of old age, even though, like cancer, it is slow, painful and undignified; and unlike cancer, it is not survivable. 

Not me.  Getting old pisses me off, frankly. 

Old age has been around a long time.  But not, according to many faiths, forever.  Adam and Eve were immortal until they ate the forbidden fruit.  Then God made them mortal.  Of course, Christians—as well as most religions I can think of actually—believe in the immortality of the soul, but that's another topic. I'm taking strictly about immortality of the flesh here.

A quick review of many faiths reveals that most gods are immortal, and the condition of being human was to be somewhere between the animals and the gods—where the rising ape meets the falling angel, to steal Terry Pratchett's phrase.  Many faiths believed that humans descended from gods and the act of becoming mortal was the act of becoming human.  That is, mortality was the defining feature of humans.

But we'll be discussing it from a Darwinian perspective, because that's the creation myth I happen to understand best, as a scientist. 

We don't have to get old and die, from a physics perspective.  We wouldn't be breaking an laws of conservation or thermodynamics by staying alive.  So why do we age?  Who decided that was a good idea?

Recently there was an interesting article in the Guardian: "Scientists Reverse Aging in Mice."  Actually, the title was  a little deceptive.  (The media? Deceptive?  Noooo.)  It's like a couple of years ago they announced that they had achieved teleportation.  I thought "Wow! That's news."  Except that they'd only teleported a subatomic particle.  Well, that should be useful if I want to send my son a frickin' proton for his birthday.

Anyways, the mice in this case weren't real mice. They were Frankenmice.  They were mice genetically engineered to age quickly, and then they fixed the genes that they had deliberately screwed up to start with.  It was still pretty impressive though.  They didn't just slow down again in old decrepit mice.  They reversed it.  These old fogie mice were growing new neurons, becoming active again and boning like crazy, excuse my French.

In other news, scientists recently discovered something about this unassuming little fellow.

Turritopsis nutricula:  the immortal jellyfish

 It's a jellyfish about as big as the head of a thumbtack.  Intensely uninteresting, you would think.  But here's the thing about Turritopsis nutricula.  It's potentially immortal.

Actually what it can do is revert to a juvenile state in times of stress.  Now when I told my buddy Mike this at the pub his response was "So what?  So can I."  You can't argue with that guy.  When times are tough for this little jellyfish, it can go back to being a polyp again when life was simple and it didn't have a care.   Wow.

Now before we get further into this, we have to make sure you understand how the whole Darwin thing works.  Old people are invisible to evolution.  If you die, before you procreate, your genes die with you and that's the end of that.  But if you manage to procreate, then your genes carry the torch for another round. 

So, if you have a gene in your DNA that creates a protein that convinces your brain that yelling, waving your arms and rolling around in gravy whenever you see a tiger is a good idea, chances are that particular gene—along with the body unfortunate enough to house that gene—is not going to last long.

(Don't laugh.  Turns out that there is a feline intestinal parasite that does just this.  If it finds itself unfortunately crapped out by the cat, it may end up being ingested by, say, a mouse.  The parasite wants to be back in a cat's digestive tract so what does it do?  That's right. It resides in the mouse's brain and convinces the mouse to engage in risky behavior to increase its chances of getting eaten by a cat.  It makes fear sexy for the mouse.  I'm not making this up.  Not only that, but it there is evidence that humans infected with this parasite also "involuntarily" engage in risky behavior.  Note to self:  future blog post on alien mind control.)

Anyways, where was I?  Oh yes, Darwin.  So, any genetic disease that effects you after you've finished all your procreating—like Alzheimer's Disease, for instance— has already been passed on to your progeny.  It will not be weeded out by evolution.  The whole basis of the theory of evolution is that you—the human being reading this—are just a particularly elaborate life support system for you genes.  That's it.  You have no other purpose except to propagate your immortal genes.  The whole thinking, being, feeling, appreciating art, striving for the divine is a side effect. An emergent property of a complex system designed to provide a nice place for your genes to hang out prior to propagation.

For the most part, your body does what it can to stay alive, so that you can procreate.  But after you're done that, and you've adequately cared for juvenile life forms that contain you genes (i.e. children), there's really no reason for your genes to go to all the trouble of keeping you around.  So it's probably no coincidence that aging really sets in with a vengeance as soon as your prime reproductive years are behind. It's also probably not a coincidence that the life spans of various animals correlate with the ages at which they reproduce and the time they spend rearing their young.  If you reproduce young, you die young.  The life spans of fruit flies were significantly extended by creating a colony that reproduced when they were older.  For animals, bivalve molluscs live the longest, flowed by tortoises.  Humans place third and elephants are behind us.

Bacteria are immortal.  Give 'em a nice place to live and they'll go on reproducing forever.  Bacteria reproduce by binary fission.  They basically clone themselves by splitting into two.  Human cells—actually all animal, plant and microorganism cells—are different.  They’re a lot bigger, to start with.  And they have a nucleus, and a double helix DNA.  In scientific terms bacteria are prokaryotes, and cells with a nucleus are eukaryotes.

The paramecium is a eukaryote.  It is a single-celled organism with a nucleus, about a million times bigger than your average bacterium.  The paramecium can reproduce by fission—or it can have sex (or what passes for sex for a paramecium).  

Parameiums getting it on.  Does this count as porn?

What's interesting is that, on the evolutionary ladder, the paramecium is about the earliest life form that (a) has sex, and (b) ages.  It seems that cell senescence (or aging) arrived the same time sex did.  There's strong evidence the two are related.  Indeed, if you are unfortuante enough to be a male praying mantis, the relationship is more than theoretical, since the female tears of the head of the male and eats him after sex.  Not much better if you're a male anglerfish, either.

 

It's interesting: Eve was tempted by the serpent to eat the forbidden fruit.  After they had eaten the apple, Adam and Eve became ashamed that they were naked, God made them mortal, cast them forth from Eden, and then they begat Cain.  So the idea that sex and death are intimately related and came about at the same time, something we theorized only a few decades ago, is echoed in the oldest writings of humanity.

Next time: Are we programmed to die?