How likely is human extinction?

Mail & Guardian Online ^ | Tuesday, April 13, 2004 | Kate Ravilious

[Momaw Nadon]

Every species seems to come and go. Some last longer than others, but nothing lasts forever. Humans are a relatively recent phenomenon, jumping out of trees and striding across the land around 200 000 years ago. Will we persist for many millions of years to come, or are we headed for an evolutionary makeover, or even extinction?

According to Reinhard Stindl, of the Institute of Medical Biology in Vienna, the answer to this question could lie at the tips of our chromosomes. In a controversial new theory he suggests that all eukaryotic species (everything except bacteria and algae) have an evolutionary "clock" that ticks through generations, counting down to an eventual extinction date. This clock might help to explain some of the more puzzling aspects of evolution, but it also overturns current thinking and even questions the orthodoxy of Darwin's natural selection.

For over 100 years, scientists have grappled with the cause of "background" extinction. Mass extinction events, like the wiping out of dinosaurs 65m years ago, are impressive and dramatic, but account for only around 4% of now extinct species. The majority slip away quietly and without any fanfare. Over 99% of all the species that ever lived on Earth have already passed on, so what happened to the species that weren't annihilated during mass extinction events?

Charles Darwin proposed that evolution is controlled by "survival of the fittest". Current natural selection models imply that evolution is a slow and steady process, with continuous genetic mutations leading to new species that find a niche to live in, or die. But digging through the layers of rock, palaeontologists have found that evolution seems to go in fits and starts. Most species seem to have long stable periods followed by a burst of change: not the slow, steady process predicted by natural selection. Originally scientists attributed this jagged pattern to the imperfections of the fossil record. But in recent years more detailed studies have backed up the idea that evolution proceeds in fits and starts.

The quiet periods in the fossil record where evolution seems to stagnate are a big problem for natural selection: evolution can't just switch on and off. Over 20 years ago the late Stephen Jay Gould suggested internal genetic mechanisms could regulate these quiet evolutionary periods but until now no-one could explain how it would work.

Stindl argues that the protective caps on the end of chromosomes, called telomeres, provide the answer. Like plastic tips on the end of shoelaces, all eukaryotic species have telomeres on the end of their chromosomes to prevent instability. However, cells seem to struggle to copy telomeres properly when they divide, and very gradually the telomeres become shorter.

Stindl's idea is that there is also a tiny loss of telomere length between each generations, mirroring the individual ageing process.

Once a telomere becomes critically short it causes diseases related to chromosomal instability, or limited tissue regeneration, such as cancer and immunodeficiency. "The shortening of telomeres between generations means that eventually the telomeres become critically short for a particular species, causing outbreaks of disease and finally a population crash," says Stindl. "It could explain the disappearance of a seemingly successful species, like Neanderthal man, with no need for external factors such as climate change."

After a population crash there are likely to be isolated groups remaining. Stindl postulates that inbreeding within these groups could "reset" the species clock, elongating telomeres and potentially starting a new species. Studies on mice provide strong evidence to support this. "Established strains of lab mice have exceptionally long telomeres compared to those in wild mice, their ancestors," says Stindl. "Those strains of lab mice were inbred intensively from a small population."

Current estimates suggest telomeres shorten only a tiny amount between each generation, taking thousands of generations to erode to a critical level. Many species can remain stable for tens to hundreds of thousands of years, creating long flat periods in evolution, when nothing much seems to happen.

Telomere erosion is a compelling theory, helping to explain some of the more mysterious patterns in evolution and extinction. There are few data - partly because telomeres are tiny and difficult to measure - but new DNA sequencing techniques could soon change that. Studies have already shown a huge variation in telomere length between different species.

Other scientists are going to take some convincing. David Jablonski, a palaeontologist from the University of Chicago, says: "The telomere hypothesis is interesting, but must be tested against factors like geographic extent, or population size and variability, that have already been proven effective in predicting extinction risk."

Stindl accepts that more experiments need to be done to test his ideas. "We need to compare average telomere lengths between endangered species and current successful species," he says. "I don't expect all endangered species to have short telomeres, since there are clearly other extinction mechanisms resulting from human threats to ecosystems, but I would expect some correlation between extinction risk and telomere length."

If Stindl is correct it will have interesting implications for mankind. Although inbreeding seems to have been the traditional way of lengthening telomeres, there could be a less drastic alternative. Stindl believes that it may be possible to elongate telomeres by increasing the activity of the enzyme telomerase in the embryo. So humans could perhaps boost biodiversity and save endangered species simply by elongating their telomeres. We may even be able to save ourselves when our own telomeres become critically short, making humans the first species to take hold of destiny and prevent their own extinction.

Indicators for human extinction Human telomeres are already relatively short. Are we likely to become extinct soon?

Cancer: Cancer incidence does seem to have increased, but it is hard to say whether this is due to longer lifespans, more pollution, or telomere erosion. The shortest telomere in humans occurs on the short arm of chromosome 17; most human cancers are affected by the loss of a tumour suppressor gene on this chromosome.

Immunodeficiency: Symptoms of an impaired immune system (like those seen in the Aids patients or the elderly) are related to telomere erosion through immune cells being unable to regenerate. Young people starting to suffer more from diseases caused by an impaired immune system might be a result of telomere shortening between generations.

Heart attacks and strokes: Vascular disease could be caused by cells lining blood vessels being unable to replace themselves - a potential symptom of telomere erosion.

Sperm counts: Reduction in male sperm count (the jury is still out on whether this is the case) may indicate severe telomere erosion, but other causes are possible.

[marron]

The idea that life is of no meaning, that it is simply a machine, that it is without purpose, that consciousness is a myth, these ideas are often difficult to refute, since they are put forward oft times by the most articulate among us. A smart guy with a gift for debate can take the losing side of an argument and run rings around his opponents, leaving them in fits, just for the fun of it.

But without debate the ideas fall of their own weight. They guy who claims that there is no purpose, will still get out of bed every morning and force his way through traffic to get to his classroom, believing somehow that it is very important that he get his message out to his students, his reading public, his peers, he will jump on planes and fly around the country to make sure his voice is heard at the right seminars.

Why, if it has no meaning? Why, if the world is just a mindless machine and he merely a mindless automaton? Why does he raise his children and sit proudly in the audience on graduation day just like all the other fools who believe it really means something?

Because life sneaks up on you, and at some point you start to care about something, your students, your family, your work, and what happens is that despite what they say from the podium, at some level they don't believe their own words, the facts of their lives are out of synch with their words. I can't speak for a specific individual, but this is what I observe in the people I know, who would be inclined to hold such opinions.

People who are inclined to argue that there is no basis for morals know that they don't want their car stolen, and they know they don't want to be robbed at gunpoint. The more they believe that there is no basis for morality, the more incoherent and paralyzed they may tend to be in the face of an attack upon themselves, but they still will reach for the phone and dial 911.

Those who believe that there is no basis for morals and actually act on it, though, find themselves at war with the world, and we send stout men with guns to confront them. Because while they may not believe it, men who do will soon be knocking on their door.

Darrow is partly right. The war against chaos, the war against death, the war against entropy is not pretty, its messy, its a hard go and its not for the faint of heart. Its beautiful, mind you, but it isn't pretty. Life is the rebellion against every physical law of the universe. You receive the spark, and you tend it while you can, and use it to light your corner of the battle field, and you try to pass it along if you can. You try to leave your corner of the universe changed for your having been there, because while you may say with your mouth that it means nothing, your very insides will drive you to act, because they are not bound by your words and they don't believe them for a moment.

[djf]

Excellent points, all!

Betty has certainly challenged me and I will try to respond.

First, my argument about Darrow's philosophy. This particular question has haunted man for as long as he lived. Why do bad things happen to good people? Why do murderers win the lottery?

Perhaps we cannot say. Perhaps all is random, and it doesn't matter a twit what we do.
Perhaps, though, most of the time, good really does succeed.

I reject both of these. I don't do charity to get a ticket to St. Peter's gate. I do it because I see a sincere need for those I try to help. It may very well end up that I am in some sort of eternal calamity no matter what I do. It is interesting that of those who have reported NDE's, a certain few actually do describe a hell. And some of those who do are what all of us would consider very righteous people.

And don't get me wrong. I have argued very vociferously that there must be some kind of reason. For exactly the same point that marron brings out, if there is no reason, then all our ideas of right and wrong, charity and chastity, are lies and worthless.

So, I resort again to the same mechanism in my earlier post.

Maybe.

Maybe.
Maybe the play we are in is not finished yet. I know Betty and I have discussed and (I think) agreed that we are active participants. Perhaps, not only might biology be evolving, but morals and ethics and purpose are evolving.

I am a great believer in some kind of destiny. And from what I see, nature may be cruel, but it abhors waste. It makes no sense to create a being and then just toss it to the wayside.

The original title of this thread is can man become extinct. My personal views are that man would be harder to terminate than cockroaches.

But here's another question: If man became extinct, would it make the evening news on Alpha Centauri?

Now, Darrow makes many good points. And I will not argue against what he perceived. In fact I argue against very little. My measure of a person has little to do with whether he believes in evolution or creation.
Personally, I see no conflict. In fact we are told: "And God said, 'Let the waters bring forth abundantly the moving creature that hath life'" Gen 1:20

And is there a difference if someone thinks there was a "big bang" or if God said 'Let there be light'"?

I believe this to be part of the mysteries. That a good soul (by whatever measure) is correct in his belief.

Betty points out the turmoil created by Darwin.
Fist and foremost, let me say this. I think Darwin was a truly intelligent man who was looking for answers. I don't think he was 'evil' or whatever. If you read "origin of the Species" it reads more like a mystery or detective novel than anything else. And Darwin himself is careful to avoid any morallistic or theological conclusions.

Realize that Darwin did his work at a time when the church(es) held almost absolute power. And think about this:
Religion, being confronted by science, seems to be slowwly fading to the background, and almost becoming nonsensical.

Now I have a large number of old texts. The Dead Sea Scrolls, the complete Nag Hammadi library, a large number of the apocrypha, multiple translations of the new testament from the Syriac Peshto.

And reading these things, I get discouraged. Seems like back then, miracles were happening all the time. On the hour. If all that stuff was true, we should be able to see miracles every night on the evening news.

Compare that idea to science. If science was wrong, I couldn't heat my soup in a microwave.

But I can.

There is a dynamic here that few recognize. Science does not (AND NEVER CAN) talk about something that is outside of, or greater than, science itself.

And nothing in religion says you should disregard science or understanding, I would argue that religion says exactly the opposite.

If science could ever prove God doesn't exist, then science would be God.

Now. If the world is nice and cushy all the time, then being nice and cushy is not all that unusual.

If the world is actually cruel and unforgiving, then maybe, just maybe, there is some sort of meaning to charity and foregiveness.

Christ told us how to pray, from the Syriac: Jesus said to them: When ye pray, thus speak ye: Our father, who art in heaven, hallowed be thy name. Thy kingdom come, thy pleasure be done, as in heaven, so on Earth.
(Luke, 11:1, Syriac Peshto 1851 translation J. Murdock)

THY kingdom come. THY pleasure be done.

Not mine. Or yours. Or anyone elses.

It has been a difficult journey for me to deanthropomorhize God. Whatever he is, wherever he is, our human comprehension and perhaps our needs our not really near the top of his to-do list.

But even by writing that, I have probably offended someone, but I had no intent. I am reminded of the scripture when the soldier asks Jesus to help him, then the soldier says I will go do it, because I know you have important work.

Which is the better lesson? We were created, without sin, in the garden, then fell, and are now trying to get back to where we were?

Or that we crawled out of the mud, vicious and hungry, and have rejected a "mine at all cost" philosophy for something greater?

I could go on for quite a bit tonight, but will give it a rest. There have been a huge number of brilliant thoughts on this thread, I hope we all can continue this discussion and reflection.

My personal conviction is somewhat gnostic, Darrow in fact said nothing new, for a good discussion about early Christian theory and practice read "The Way of the Mystics, the Early Christian Mystics and the rise of the Sufis " by Margaret Smith, Oxford U press, 1978.

Ultimately, I will condemn no one. Some people live a life of pleasure and excess, it is not my preogative to say they are wrong. I have had my share. Neither can I condemn anyone else for their beliefs, I will only comment on extremism.

I haven't even come close to talking about all the ideas on the thread, my only recommendation is "Be Honest!".



Breaking news from channel &$@ on Alpha Centaurii:

The humanoids on Earth narrowly avoided nuclear devastation when a mugger being persued by police fired a shot, and accidentally destroyed the trigger on the Post-fusion weapon they had invented...

more at 11.

[djf]

And let me add this little bit. People tend to thin of man as a spiritual being.

Hogwash.

Man is more spiritual than a donkey. But he is still 95% animal.
And I would honestly argue that my dog is more spiritual than some people I have met.


And that is what I was clumsily trying to say in my earlier post to Betty. All of our dreams of charity and honor and goodness are not all we make of them.

But we are as tiny bits of crystal, thrown on a beach, and those dreams and endeavors reflect a SMALL part of God.

An evolution of the idea of man and nature and purpose is perhaps even more radical than an idea of the evolution of biology.

God Bless all, night!

[betty boop]

Sorry. Mid-to-late-1800s is the 19th century. Thanks for the correction RWP.

[Diamond]

There is a parallel among the metaphysical naturalists (atheists). Some of the "second reality" science theory precludes free will because it claims that consciousness et al is merely an epiphenomenon of the physical brain. The theory presents a quandary for the rule of law. A murderer cannot be personally responsible for doing what his brain compelled him to do. The response to this claim is basically this (paraphrased): the murderer indeed has no personal responsibility but members of society must also likewise punish him to carry out their own physical brain functions. This is a form of strong determinism (predestination) based on a presumed causality in nature. But causality is not what it seems, especially with regard to space/time and superposition.

Meditating on these points of views – I see little practical difference between the religious and the secular who believe there is no free will because neither accept personal responsibility. One lays it at the feet of “nature” the other at the feet of God.

IMHO, escaping personal responsibility by either theology or theory is a self serving illusion – neither recognizing the power of God nor the nature of time.

Alamo-Girl, while I agree with you that there there is no escaping personal responsibility by laying it at the feet of either 'nature' or of God, I do not believe there is a real parallel between materialistic determinism and Biblical predestination. Without the power and sovereignty of God, free will is impossible in the first place. See this new thread: Understanding the Will

Cordially,

[betty boop]

...at some level they don't believe their own words, the facts of their lives are out of synch with their words.

I think many people these days would rather "live in their heads" than live in the world. They want to go live in some grandiose theory, instead of in this reality to which we are inextricably bound. Perhaps they wish to subject reality to their own preferred system, to make it a slave of ideology. But this is an exercise in futility. If there is to be a war between the head and the heart, there can be no victor, for both must lose in such pointless strife.

It seems best to make our ideas conform to what really is, than to make what really is conform to our ideas. To attempt the latter is to wish to do the impossible. Reality doesn't strike me as being particularly compliant with or willing to conform to our wishes.

This statement is so true: "...you may say with your mouth that [life] means nothing, [but] your very insides will drive you to act, because they are not bound by your words and they don't believe them for a moment."

Beautiful, eloquent essay, marron. Thank you so very much!

[Alamo-Girl]

Wow! Another beautiful essay, marron! Thank you so very much.

[Alamo-Girl]

Thank you so much for your fascinating essay and testimonial!

It has been a difficult journey for me to deanthropomorhize God.

I think you have your hand on the door knob.

But as long as anyone is characterizing God by his own thinking, he is creating a god of his own imaginings. That is why the following statement you made rings true to me whenever man’s doctrines and traditions (as opposed to the living Word) refute science:

Religion, being confronted by science, seems to be slowwly fading to the background, and almost becoming nonsensical.

Conversely, spiritual thirst is increasing among the “non-aligned” and the Bible centric. For evidence I point to the eerie success of movies dealing squarely with issues of good v evil – The Passion of the Christ, of course but also the Lord of the Rings trilogy and many others. The same is true of popular television programs, the good confronting evil and winning the battle.

I share your interest in ancient manuscripts and am particularly drawn to Charlesworth’s collection. I read all of it as literature unless the Spirit within brings something to my attention, which He has with regard to Abraham's reason for leaving his father and much of the book of Enoch. Which brings me back to the door knob.

It has been a difficult journey for me to deanthropomorhize God.

The door knob is turned when we surrender to God and specifically ask for and receive His indwelling Spirit. He is alive and whereas the Scriptures reveal Him truly, they do not reveal Him fully. He reveals Himself directly, personally, organically - as He wills. We cannot mentally grasp Him - as you have said.

You might be interested in in this short thread for more.

[Hacksaw]

Human extinction is 100%, it's just a matter of when, if it's 'natural', or self-induced.

Doubtful. As we colonize space, we will keep evolving.

[Alamo-Girl]

Thank you so much for your post and for the link! It was an interesting thread!

Without the power and sovereignty of God, free will is impossible in the first place.

I agree. But I would extend the remark by asserting that it is the interaction of the spirit and God which overrides predestination, i.e. strong determinism.

This is related to my musings on the nature of time: post 34

[Hacksaw]

Second, it's ridiculous to believe that because wolves and bears and snakes no longer have us on the menu, we are therefore under no genetic selection pressure. It's just that the pressures have changed. In the past century, the Tasmanians were wiped out, segments of the Bantu, Hottentot and Siamese populations were dealt serious blows from the AIDS epidemic (along with any genes responsible for male homosexuality in the West), and white Caucasians decided to stop replacing their numbers through breeding. I'm sure you can come up with many more examples, besides.

He is right to a point. Physical defects that would otherwise result in death are now compensated for. Bad heart - get a pacemaker. Bad eyes? Surgery. Bad kidney - get a transplant.

[Physicist]

He is right to a point. Physical defects that would otherwise result in death are now compensated for. Bad heart - get a pacemaker. Bad eyes? Surgery. Bad kidney - get a transplant.

As I said, the selection pressures have changed. But I don't concede that donh was right at all. "Bad heart", "Bad eyes", "Bad kidney"..."bad" for what?

And you...just look at you! Bad gills. Bad fins. Bad tail. How do you expect to survive, you degenerate?

[Hacksaw]

As I said, the selection pressures have changed. But I don't concede that donh was right at all. "Bad heart", "Bad eyes", "Bad kidney"..."bad" for what?

Bad as in that would otherwise result in death and prevent having children, passing the same genes along that would have to be compensated for later.

And you...just look at you! Bad gills. Bad fins. Bad tail. How do you expect to survive, you degenerate?

My aquatic adventures are not a debate issue. How did you find out about that?

[djf]

I think that Darwinism and Newtonian thought created a somewhat awkward time for people. That was why I emphasized the seeming clash between science and religion.

But, IMHO, no such clash actually exists. As you so rightly pointed out in an earlier post, Bell's ideas have opened up entire new vistas of thought about time and space and connectivity.

The collapse of locality, spatial and temporal, at least allows us to see a much bigger picture of cause and effect. By it's very nature, we are potentially thrust into being more an intrinsic part of things than we ever could have thought possible in the past.

And these new vistas of science and QM, Wheelers multiple universe theories,(which I reject), etc. start to give us a tiny glance, as if we were looking through a peephole, at the magnificence and utter hugeness of what's out there.

I find a deep spiritual beauty in the following:

Part 1: Matter organizes itself into living beings
Part 2: Living beings aspire to attain spiritual elegance, meaning, and purpose


But I have to admit, often, in the middle of the night, alone and deep in thought and memories of my life, I kinda wish that He would just knock on my door, come in and have a cup of coffee with me, and chat for awhile.

;}

[Physicist]

Bad as in that would otherwise result in death and prevent having children, passing the same genes along that would have to be compensated for later.

Define "otherwise".

My aquatic adventures are not a debate issue. How did you find out about that?

Faith, sir, they are written in your genes.

[Hacksaw]

Define otherwise

oth·er·wise

adverb

1. or else: if things had been different “I overslept,” said Joe, “otherwise you would have heard from me earlier.”

2. differently: different from or opposite to something stated You may take your hand luggage with you unless otherwise requested.

3. in other ways: in any other ways An otherwise dull day was enlivened by her arrival.

[Old English (on) (in) (an)other wise, manner”]

[Alamo-Girl]

Thank you oh so very much for your beautiful post! I strongly share your wonder over the new horizons of science.

But I have to admit, often, in the middle of the night, alone and deep in thought and memories of my life, I kinda wish that He would just knock on my door, come in and have a cup of coffee with me, and chat for awhile.

Are you quite sure that you haven't chatted with His agents?

Be not forgetful to entertain strangers: for thereby some have entertained angels unawares. - Hebrews 13:2

[djf]

Oddly enough, the other night, about 2 AM, there was a heck of a ruckus on my front porch. So I open the door, and he was out there, whining and wagging his tail, all excited.

There's a beagle that lives in the neighborhood who has taken a liking to me.

Neat little pup, so I let him in and gave him some cheese.

I just wish his owners would give him a bath. He's kinda greasy.

[Alamo-Girl]

LOLOL! What a precious story! I don't recall a specific story about an angel appearing as an animal, but then again there was Balaam's ass who spoke in Numbers 22...

[Jimmy Valentine]

"We'll get about a 20 minute warning before the pyroclastic flow rolls though here."

That's not much time. I guess you can forget about doing a load of laundry before you skedaddle.

Regards,