Monday, January 10, 2011

How come evolution hasn’t made us immortal? Death, like sex, helps animal populations avoid extinction

Genes do not evolve, nor do traits that are coded for our genes. We say that they evolve to facilitate discourse, which is alright. Populations evolve. A new genotype appears in a population and then either spreads or disappears. If it spreads, then the population is said to be evolving with respect to that genotype. A genotype may spread to an entire population; in population genetics, this is called “fixation”.

(Human chromosomes capped by telomeres, the white areas at the ends. Telomere shortening is caused by oxidative stress, and seems to be associated with death of cells and organisms. Source: Wikipedia.)

Asexual reproduction is very uncommon among animals. The most accepted theory to explain this is that animal populations live in environments that change very quickly, and thus need a great deal of genetic diversity within them to cope with the change. Otherwise they disappear, and so do their genes. Asexual reproduction leads to dramatically less genetic diversity in populations than sexual reproduction.

Asexual reproduction is similar to cloning. Each new individual looks a lot like its single parent. This does not work well in populations where individuals live relatively long lives. And even 1 year may be too long in this respect. It is just too much time to wait for a possible new mutation that will bring in some genetic diversity. To complicate matters, genetic mutation does not occur very often, and most genetic mutations are neutral with respect to the phenotype (i.e., they don’t code for any trait).

This is not so much of a problem for species whose members reproduce extremely fast; e.g., produce a new generation in less than 1 hour. A fast-reproducing species usually has a short lifespan as well. Accordingly, asexual reproduction is common among short-lived and fast-reproducing unicellular organisms and pathogens that have no cell structure like viruses.

Bacteria and viruses, in particular, form a part of the environment in which animals live that require animal populations to have a large amount of genetic diversity. Animal populations with low genetic diversity are unlikely to be able to cope with the barrage of diseases caused by these fast-mutating parasites.

We make sex chiefly because of the parasites.

And what about death? What does it bring to the table for a population?

Let us look at the other extreme – immortality. Immortality is very problematic in evolutionary terms because a population of immortal individuals would quickly outgrow its resources. That would happen too fast for the population to evolve enough intelligence to be able to use resources beyond those that were locally available.

In this post I assume that immortality is not the same as indestructibility. Here immortality is equated to the absence of aging as we know it. In this sense, immortals can still die by accident or due to disease. They simply do not age. For immortals, susceptibility to disease does not go up with age.

One could argue that a population of immortal individuals who did not reproduce would have done just fine. But that is not correct, because in this case immortality would be akin to cloning, but worse. Genetic diversity would not grow, as no mutations would occur. The fixed population of immortals would be unable to cope with fast-mutating parasites.

There is so much selection pressure against immortality in nature that it is no surprise that animals of very few species live more than 60 years on average. Humans are at the high end of the longevity scale. They are there for a few reasons. One is that our ancestors had offspring that required extra care, which led to an increase in the parents’ longevity. The offspring required extra care chiefly because of their large brains.

That increase in longevity was likely due to genetic mutations that helped our ancestors extend a lifespan that was programmed to be relatively short. Immortality is not a sound strategy for population survival, and thus there are probably many mechanisms through which it is prevented.

Death is evolution’s main ally. Sex is a very good helper. Both increase genetic diversity in populations.

We can use our knowledge of evolution to live better today. The aging clock can be slowed significantly via evolutionarily sound diet and lifestyle changes, essentially because some of our modern diet and lifestyle choices accelerate aging a lot. But diet and lifestyle changes probably will not make people live to 150.

If we want to become immortal, as we understand it in our current human form, ultimately we may want to beat evolution. In this sense, only very intelligent beings can become immortal.

Maybe we can achieve that by changing our genes, or by learning how to transfer our consciousness “software” into robots. In doing so, however, we may become something different; something that is not human and thus doesn’t see things in the same way as a human does. A conscious robot, without the hormones that so heavily influence human behavior, may find that being alive is pointless.

There is another problem. What if the only natural way to achieve some form of immortality is through organic death, but in a way that we don’t understand? This is not a matter of faith or religion. There are many things that we don’t know for sure. This is probably the biggest mystery of all; one that we cannot unravel in our current human state.

31 comments:

Anonymous said...

Thought provoking. L I love it !!

js290 said...

Ned,

you're referring to biological immortality.

Ned Kock said...

Hi js290. Rose’s “immortal phase”, which is indeed related to a real phenomenon that happens at very advanced ages, reminds of the struldbrugs:

http://en.wikipedia.org/wiki/Struldbrug

Anonymous said...

A pleasant post to read and ponder. You have simple, yet quite effective and enjoyable way of presenting your hypothesis; thank you Ned.

David Isaak said...

When he knew he was dying, filmmaker David Lean (Bridge Over the River Kwai, Lawrence of Arabia, Dr Zhivago, etc) lamented "And just when I was starting to get the hang of it..."

I don't demand immortality, but I could usefully employ another hundred years of good health.

Avishek said...

you are describing yogis and buddhist monks, and taoists, of whom there are many reports of incredible longevity. Of course it is hard to believe such things, but those people are definitely different from normal humans

Ned Kock said...

Actually I doubt that there has ever been a human being that lived to be 150, but I may be wrong. The lady on the article linked by js290 lived to be 122; she is considered to have been the world’s oldest person ever.

malpaz said...

you know this post made me think....if there was the possibility of immorality, you would never die, i bet a lot of people could learn to CALM down and stop stressing. if you always knew tomorrow would be here, dont you think you would always want to genuinely do well. there would be no finish line, nothing to prove ;while youre here', no debts to have 'x' years to pay off, no rush to the end of life trying to accomplisn x y and z...

i dunno, just what sparked my thought

Ned Kock said...

Hi Mal. Actually thinking that, and acting as though, you will live a long life is one of the common characteristics of the Okinawans. Their approach goes something like this: “Don’t sweat it, there are several years ahead, it will get done.” It certainly reduces stress, which may be one of the biggest killers in modern urban societies. This may contribute to them living long and health lives, even though they may also be genetically more likely to do so.

malpaz said...

no joke, ever since i read this post i have been telling myself that. pretend i can live forever, and all the sudden i just calm down. its strange, but i like it, especially when i am trying to go to bed!

anonymoose said...

How does this tie in with telomeres?

My understanding is that this bit of dna that is attached to the end, is responsible for the lifespan of a cell.

If we could increase the lifespan of cell, would that be heading towards immortality?


The flip side of having no telomeres of course is rougue cells. Cancer cells for example, can continue to live and replicate without ever dying.

No free lunch I suppose.

Ned Kock said...

Anonymoose, I guess you answered your own question. It is a bit like targeted drugs that supposedly decrease heart disease, and then end up giving you cancer. One way or another, nature makes sure that you are not around for too long.

Avishek said...

why would you doubt there has ever been a human who has lived longer than 150? Do you really believe that the accepted 122 is the truth because it is verified by the more meticulous records we have today? I would not like to argue this, but the historical accounts of incredible long lived individuals, many of which have been verified cannot be ignored.

Ned Kock said...

Hi Avishek. I would be interested in seeing those records, or getting a link. Perhaps there have been very long-lived individuals in the past, who lived to 150 or beyond, but apparently their genes disappeared. If not, at least some of their descendants would be making news today, as longevity is in part inherited.

Ned Kock said...

By the way, years ago I was on a tour of Hawaii and the guide said that there was “undisputable” evidence that some of their ancestors were 10 feet tall and lived hundreds of years. Supposedly the evidence was from reliable dating techniques and the proof of the height was the size of the skeletons. Still, there has been no endorsement from the scientific community.

I find the claim regarding height more believable, although somewhat exaggerated. Gigantism happens, and it is a disease usually caused by a tumor on the pituitary gland. People who suffer from it can be very tall, reaching almost the height of 9 feet, and live very short lives. See the article below for Robert Wadlow, considered to have been the tallest person ever. He died at age 22.

http://en.wikipedia.org/wiki/Robert_Wadlow

David Isaak said...

Yeah, I used to live in Hawaii, and I listened to that "our ancestors were ten feet tall" nonsense many times. There isn't any indisputable evidence. In fact, there isn't any evidence at all.

The ruling class--the Ali'i, who are now believed to have conquered the islands and imposed their rule on the earlier, smaller people--were probably Samoans. And Samoans are mighty large people, normally over six feet, sometimes pushing up toward seven feet, and massive on top of it.

Not ten feet tall. But they might have seemed ten feet tall to the commoners, who usually didn't have enough to eat. (The last famine in what is now the United States happened in the Ka'u district of the island of Hawai'i.)

Ned Kock said...
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Ned Kock said...

Right, there are many Samoans in New Zealand as well. Dwayne "The Rock" Johnson is Samoan, if I am not mistaken. So is David Tua (boxer) and Mark Hunt (MMA fighter). These guys are massive, and a few extra pounds of body fat do not seem to have any negative effect on them.

Avishek said...

Nice, I had no idea gigantism was related to longevity, but that is what the science says, I have heard about Waldow and the complications in the various organs that ensue from such physical stature.

None of the evidence on incredibly long lived people is 'scientific.' Modern science is very narrow and reductionist of course, while the science in indigenous tribes tends to be holistic. There is evidence from indian and tibetan/taoist/buddhist mindsets regarding incredibly long lived people.
Here is an article of this
http://www.secrets-of-longevity-in-humans.com/longevity-in-humans.html
That is not very scientific but that's what I could find online.
However, the accounts I have read are from some books. One of them was "Chinese Tonic Herbs" by Ron Teeguarden. There are a couple accounts there. Here is the story of one such account of the 252 year old Li Qing Yuen, a Taoist. What's important to note is that the Taoists revered longevity. The chinese have a knack for understanding how health comes from within, as seen by their development of medicine, and exercises such as qiqong which support longevity and 'life force,' of qi (chi) as well as jing.
http://sta8love8.blogspot.com/2009/04/252-years-old-teh-secret-revelead-here.html

He ate the goji berries everyday, apparently
In fact the words sound the same I wonder if the author transcribed that segment from the book as it sounds the same.

Also the "Autobiography of a Yogi" is a great book. Many yogis have reported to living very long, one lived to 186 apparently and decided to leave after finding the purpose of life. Dr. Gabriel Cousens talked about him, but the point is that their spiritual practice has an effect on the body that is above and beyond food and exercise, and above the grasp of current science, although many scientists have studied yogis and been perplexed.

The "Holographic Universe" I am reading now and again seeing how there is much greater than food to overall health, like emotional health which manifests in many physical diseases. Psychics who can detect diseases before physical symptoms however say that thought patterns influence the 'aura' around the body, and then the physical is affected.


Lastly, "The Body Electric" is a great book to read because it is modern science, however it is placed int he alternative medicine section since the research is not accepted. If you read through it you may notice how it is pretty unbiased and scientific. I am mentioning this book because it may eplain many unscientifically regarded healing modalities from the East: through the electrical properties of the body. So perhaps the exercises and herbs the taoists ate for longevity acted through electricity. Also I believe he mentions briefly that yogis can control this electric field to a degree, which may impart significant health benefits. They of course do not eat much food, which also increases longevity.

Sorry one more thing, might as well add what I can. About electricity: the soil is negatively charged, containing electrons, some evidence of this is presented in "Earthing" which I have not read, so i cannot recommend it yet. However, studies have shown that "grounding," the act of connecting with the earth, by touching the ground, unclumps blood within 30 minutes. That must have a remarkable impact on health.

This information certainly is not accepted by the scientific community, however much of the evidence itself is indeed scientific, and produced from the scientific method, while others we need to wrap our heads around in the way the scientific method cannot.

Avishek said...
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Avishek said...
This comment has been removed by the author.
Avishek said...

Interesting, I had not heard of that. I have heard of Waldow and the complications that frequently ensue in the organs from such large stature so that makes sense.

Certainly modern science does not accept that anybody ever lived past 122. There is evidence from indian and tibetan/taoist/buddhist mindsets regarding incredibly long lived people.
Here is an article of this
http://www.secrets-of-longevity-in-humans.com/longevity-in-humans.html
That is not very scientific but that's what I could find online.
However, other accounts I have read are from some books. One of them was "Chinese Tonic Herbs" by Ron Teeguarden. Here is the story of one such account of the 252 year old Li Qing Yuen, a Taoist, a very widely accepted figure for longevity. What's important to note is that the Taoists revered longevity.
http://sta8love8.blogspot.com/2009/04/252-years-old-teh-secret-revelead-here.html

He ate the goji berries everyday and that link is the basic story.

Also the "Autobiography of a Yogi" is a great book. Many yogis have reported to living very long, one lived to 186 apparently and decided to leave after finding the purpose of life. Dr. Gabriel Cousens talked about him, but the point is that their spiritual practice has an effect on the body that is above and beyond food and exercise, and above the grasp of current science, although many scientists have studied yogis and been perplexed.

The "Holographic Universe" I will mention simply because science cannot explain much of the paranormal psychical phenomena presented there. Quantum physics probably will though in the coming centuries. It also influenced my thinking that food and exercise are very limited ways to improve our health


Lastly, "The Body Electric" is a great book to read because it may explain how many of the phenomena work. It is the most scientific work I have presented thus far. It is ironic that the book is placed in the "alternative medicine" section as the author was born into the modern scientific community. He mentions how yogis could influence the electromagnetic fields.


This information certainly is not accepted by the scientific community, however much of the evidence itself is indeed scientific, and produced from the scientific method, while others we need to wrap our heads around in the way the scientific method cannot.

Avishek said...
This comment has been removed by the author.
Avishek said...
This comment has been removed by the author.
Avishek said...

my bad haha

Ned Kock said...

Thanks for the info and links Avishek.

Anonymous said...

http://www.admin.cam.ac.uk/news/dp/2011012601

Dan M. said...

Good Episode

http://video.pbs.org/video/1754557053

Ned Kock said...

Thanks Dan. I've seen that episode on TV, and it is indeed very good.

Interesting information, but a little outdated, about the genes coding for FOX proteins.

Anonymous said...

Long living cells (i.e. long Telomeres) are apparently associated with a REDUCED cancer risk?

http://www.healthiertalk.com/more-telomeres-and-cancer-3344

Happy said...

Hi,

Great article, well reasoned and well presented. I came to a similar, if not so elegant, conclusion after someone asked me how evolution could be true if it hadn't out-evolved death. The problem parasites & disease present is a strong argument which evaded me, I don't have much knowledge of the life sciences, but I came up with plenty of other reasons why immortality would be a blind alley for life to go down. The massive climate changes in history would likely finish immortal life off if, as you already pointed out, the population didn't outgrow its resources first or it didn't get eaten or destroy itself the way man seems happy to.

Taking it a bit further, though, I concluded that evolution actually has conquered death. If you consider all life as a collective organism, evolution is the only way this side of indestructible super creatures to ensure the immortality of that organism .

I don't know if a person living a reasonable life span has many, if any of the individual cells they started out with. We consider ourselves to be the same person at 90 as we were when we were born but the broom has had quite a few new handles and heads along the way. Life on this planet is related in a far more complex way than the cells in even the most sophisticated animal, so if we remain essentially the same though our cells grow and die, the extinction and creation of species doesn't necessarily mean the organism is not essentially the same even though its component parts haven't just been replaced but have changed along the way.

It seems reasonable to conclude that eternal life on the individual level has been rejected by evolution as a literal dead end, though I wonder if it ever tried it out. Whether some extinct test branch of immortal life lies buried under a volcano somewhere. Still, it's hard to imagine ever obtaining enough satisfaction from knowing our collective organism may have endless longevity to say, okay, this is enough living for me.