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?