Speaking of self-repair, here’s a fascinating new finding from Malin Hernebring in Sweden. Here’s the technical paper, from a few years ago; it’s part of Hernebring’s Ph.D. thesis work. (Via Richard Dawkins’s site.)
As we age, our cells gradually decay; the DNA stays relatively intact, but proteins degrade with time. This is a big part of the aging process, leading to wrinkled skin as well as more serious consequences. When you think about it a bit, that raises a puzzle. A newborn baby arises out of the cells of its parents. So if the proteins simply decay without repair, every generation would get handed down a degraded set of proteins. At some point, therefore, there has to be some repair job, so that the baby gets fully functioning proteins.
If this idea is right, you might guess that the repairs happen at the level of ovum and sperm; maybe when these cells are created, extra effort goes into tuning up their proteins into working order. But the new research says no — it’s actually after conception that the clean-up crew arrives. The newly conceived embryo consists of stem cells that soon begin differentiating themselves into the different kind of mature cells. It turns out that it’s during this differentiation process that proteasomes go to work, breaking down the damaged proteins and generally tuning up the engine. (Maybe this is when the soul is implanted in the embryo?)
The next obvious question is: why can’t these cellular clean-up crews be active all the time? There are clear implications for studies of (and therapeutic approaches to) aging. Nature wants all the individual animal organisms to die, making room for new generations; but there’s no reason we have to go along with the plan.
Believe you me: I loves me a little bio-talk in a physics forum, and hate to go OT. But this supraluminal neutrino thing is blowing my desperately hopeful, probably gullible little mind. This is crying out like bloody murder for a reality check in a forum like this blog…just sayin’…
@ Low Math, haha, indeed – checked here to read about those FTL neutrinos and ended up with this!
Great stuff though – I don’t fancy dying at all if I can avoid it. At the very least, id like to be in possession of all my faculties until as near as possible to the end. If this kind of research can improve quality of life, I’m all for that.
Agreed on the FTL neutrinos.
My favorite speculation so far: Perhaps it has a small probability of temporarily existing at a velocity slightly greater than the speed of light (or goes back in time, same thing I think) via some sort of quantum fluctuation in where its already tiny mass can temporarily become slightly negative or even imaginary.
(HT to commenter jsberry at physorg.com)
Ahhh! I don’t want to hijack, just didn’t know where else to bring it up!
There is some evidence that the body uses vitamin in D to switch on many different processes involved in properly maintaining the body:
T cells only activate when they are exposed to vitamin D
vitamin D stimulates gingival cells and lung cells to produce a natural antibiotic
And there has been a lot more results like this that show that vtamin D is involved in regulating processes that maintain the body, from regulating the immune system to building muscles etc.
This suggests that even these basic self-maintainance activities are considered to be luxery, the body will cut back on them if vitamin D levels are low. Presumably, the body uses vitamin D as an indicator for the availability of food. Our ancestors would have had lower vitamin D levels in the Fall. Precisely at that time it would make sense to cut back on energy use to build up fat reserves for the coming Winter.
It could thus be that a body that doesn’t age would need to expend a huge amount of energy in mantainance costs. You would be eating and sleeping all day long without being able to do any physics.
David H: “AI – What you’re proposing is a classic example of group selection that just doesn’t work. Group selection only works when competition between groups overwhelms competition within groups. The advantage to an organism which cheated, and avoided dying to produce more offspring, or avoided dying off during famine would be tremendous, whereas the advantage to others provided by its dying would be spread over its children and every other organism in the population….”
First of all the claim that “group selection only works when competition between groups overwhelms competition within groups” is patently absurd. Wherever there is competition there is selection, selection works on all levels all the time, there is no “either or” here.
What’s more in the case of animals which depend on the group for their survival evolutionary resilience of the whole group is always far more important then relative success of any individual within the group (measured as the number of offspring produced relative to his peers). If the group goes extinct all it’s members go extinct with it, how they compared among themselves is completely irrelevant at this point.
As for your counterexamples, the part about famine makes no sense whatsoever (did i claim dying to famine is beneficial?). As for the number of offspring, when producing more offspring is beneficial organisms simply produce more offspring, they don’t have to live longer to do it. Lifespan is all about the speed of evolution, longer lifespan means slower adaptation and is therefore not beneficial.
For example let’s say you start with 2 otherwise identical groups, A and B, which differ in that individuals in group A live 10 times longer then those in group B, the number of offspring per lifetime is the same in both groups. Group B will of course outcompete group A since it can evolve new adaptations 10 times faster (group B produces 10 generations in time it takes group A to produce one).
Low Math, Meekly Interacting great post, learned a lot!! Such a rich,beautiful system life is!
AI –
To address your points:
1. “selection works on all levels all the time” – indeed it does. But selection pressures at different levels can be in conflict, especially for altruistic adaptations, which by definition are detrimental to the individual. For group altruism to evolve, the benefit to the group must outweigh this cost to the individual. Sometimes this happens, emphasis on “sometimes”. But even biologists who support group selection agree that this is not common.
2. “resilience of the whole group is always far more important then relative success of any individual within the group” – again, yes, sometimes, but not often, and only in strongly social species. Aging is nearly universal, it occurs in herd animals and lone predators, autotrophs and heterotrophs; why is it maintained in all these non-social species?
3. “did I claim dying to famine is beneficial?” – I’m not sure how else to interpret your previous statement: “it is a great mechanism to ensure that in times of stress (limited resources…) it is those old individuals who will die first, this prevents them from outcompeting the younger generations”. What else is a time of stress involving limited resources?
4. “Lifespan is all about the speed of evolution, longer lifespan means slower adaptation and is therefore not beneficial” – No, lower rates of reproduction means slower adaptation: fewer offspring, fewer new variants for selection to test. A longer lifespan at the same rate of reproduction would be beneficial, allowing more total offspring. It’s detrimental only if it is linked to lower fertility; this is GC Williams “Antagonistic Pleiotropy.” If every extra year of life requires fewer offspring per year, then nature will select shorter lifespans and more offspring. But this is selection at the level of individuals (because energy spent keeping alive is energy not spent making babies, or longer life can only come at the cost of delayed sexual maturity, etc), and is maximizing individuals’, not group, fitness. Your example is a perfect illustration: group B reproduces 10 times as fast as group A. It doesn’t only evolve faster, it just plain old outcompetes A; if groups A and B were mixed, B’s would still win, they are more fit individuals.
Look, this isn’t an ideal place for substantial scientific debate, and your theory is something that people did subscribe to in the past. I suggested reading up on, or about, GC Williams, who was one of the first to explain these issues. I also suggest checking out this post from DS Wilson, one of the premier evolutionary biologists who studies group selection, where he describes the problem with naïve group selectionism: http://scienceblogs.com/evolution/2009/10/truth_and_reconciliation_for_g_1.php (in fact, I recommend the entire series). But who knows, I could be wrong; I’ll repeat what I asked of Nullius in Verba – I’d love to see references to your theory that explain it in detail and discuss the supporting evidence.
-David
David: 1. “selection works on all levels all the time” – indeed it does. But selection pressures at different levels can be in conflict, especially for altruistic adaptations, which by definition are detrimental to the individual. For group altruism to evolve, the benefit to the group must outweigh this cost to the individual.
Well, this is obvious, I don’t see how it contradicts anything I said.
David: 2. “resilience of the whole group is always far more important then relative success of any individual within the group” – again, yes, sometimes, but not often, and only in strongly social species. Aging is nearly universal, it occurs in herd animals and lone predators, autotrophs and heterotrophs; why is it maintained in all these non-social species?
The reason has to do with competing with one’s own offspring. But let’s stick to lifespan for now, this is a simpler case, and even there you don’t seem to understand my argument.
David: 3. “did I claim dying to famine is beneficial?” – I’m not sure how else to interpret your previous statement: “it is a great mechanism to ensure that in times of stress (limited resources…) it is those old individuals who will die first, this prevents them from outcompeting the younger generations”. What else is a time of stress involving limited resources?
Yes, but again that was about aging, not lifespan, you switch between the two as if they are the same thing, but they are not, there are different reasons behind each. The part you quote wasn’t stating that dying to famine is beneficial, only that when a certain % of population is to die, it is better if it’s the older generations who die. That much is even hardcoded in our own instinct, parents often prefer to die in place of their kids.
David: 4. “Lifespan is all about the speed of evolution, longer lifespan means slower adaptation and is therefore not beneficial” – No, lower rates of reproduction means slower adaptation: fewer offspring, fewer new variants for selection to test.
Testing new variants is not adaptation, adaptation is about spreading them, you want more generations to amplify new beneficial trait and mix it with other beneficial traits (many of which will not be present in the original “inventor”) , this cannot be achieved by one individual (especially the latter part which is critically important for genetic diversity and therefore population health).
David: A longer lifespan at the same rate of reproduction would be beneficial, allowing more total offspring.
First of all you are assuming that more offspring equals success, but this is obviously wrong. Why do you think twins are so rare and multiplets even rarer? From biological perspective it’s trivial to produce them. It’s successful offspring that count, and producing too many offspring can lower the chances of success of them all.
More generations always beats more offspring.
David: It’s detrimental only if it is linked to lower fertility; this is GC Williams “Antagonistic Pleiotropy.”
Look, I don’t appreciate arguments from authority, but even GC Williams knew that group selection does work for closely related individuals and that’s more then enough to support my argument.
David: “If every extra year of life requires fewer offspring per year…”
Sorry, but what does that even mean?
David: Your example is a perfect illustration: group B reproduces 10 times as fast as group A. It doesn’t only evolve faster, it just plain old outcompetes A; if groups A and B were mixed, B’s would still win, they are more fit individuals.
But it outcompetes A precisely because it evolves faster! At the start they are equally well adapted, and their population numbers are exactly the same. B don’t start more fit, they eventually win precisely because they adapt faster due to shorter life cycle!
Sorry but the above is the most important part here and it cannot be explained more clearly, if you don’t get this example then I don’t think I can help.
David: Look, this isn’t an ideal place for substantial scientific debate, and your theory is something that people did subscribe to in the past. I suggested reading up on, or about, GC Williams, who was one of the first to explain these issues. I also suggest checking out this post from DS Wilson, one of the premier evolutionary biologists who studies group selection…
This is as good a place as any. As for the latter I don’t much care about current fads and sociology of the field, selection works on all levels, even GC Williams knew that much even though he built his career on questioning it’s relative importance.
You have yet to articulate any valid counter argument to my example, saying that it’s a group selection and some people think group selection is unimportant does not count as a valid counter argument.
Finally my point is valid even in terms of individual selection, as long as you define “evolutionary success” properly and not by such simplistic measures as number off offspring. For example if you define success as the percentage of population gene pool that can be traced back to a given individual over a long period of time, then you will arrive at the same conclusions – in general it is better to amplify beneficial traits through many short generations then through one individual dominating the gene pool which makes the whole population (his offspring included) more vulnerable through depletion of genetic variety.
If the population goes extinct the individual success of all it’s members is null.
David: I’d love to see references to your theory that explain it in detail and discuss the supporting evidence.
The theory in question is the theory of evolution, my statements and examples concerning lifespan follow directly from it.
(Maybe this is when the soul is implanted in the embryo?)
**********
WHAT? What “soul”? How DARE you put something totally religious (and as valid as thinking there is a Mars, “god of war’) into an article about SCIENCE.
Ok, I’m mostly done here, but to focus on your model for a second: A organisms have 10 times the lifespan of B organisms, each produce the same # of offspring per lifetime, so if we say that # is 10 offspring and A’s live for 10 years, then on average, A’s produce 1 offspring per year for 10 years and B’s produce 10 offspring per year for 1 year. In a mixed population of, say, 10 A’s and 10 B’s, all young so they have their entire lifespan ahead of them, in a year there will be 10 new A’s and 100 new B’s, while all the old A’s are still around but all the old B’s die. Now we have 20 A’s and 100 B’s. Repeat, and the next year you have 40 A’s and 1000 B’s. It gets worse from there, B’s are much more fit, because they grow faster, this isn’t even evolution, it’s simple population dynamics.
As for the rest, we’re just circling each other. I’ve explained group selection for altruism only works under special conditions, and I’ve yet to see any explanation for why those conditions would hold for nearly every animal on the planet. I’m honest about my request for a reference, by necessity your argument is short here, and if it so clearly follows from the basics of evolution, then there should be a paper out there that explains it in detail. I’ll be glad to be proven wrong. And if there is no such paper, but you think the answer is so clear, then there’s a golden opportunity: write something up, upend our current understanding of aging and lifespan, earn scientific immortality.
Ok, that’s all. I’d love to see a reference, but otherwise I think we’re done here.
-david
I’m glad that you agree that B are much more fit due to shorter lifecycle, but your analysis makes one very unrealistic assumption – that environment can support any number of organisms A and B.
The assumption in my analysis (which i should have made explicit) was that an environment can only support a certain number of organisms A and B (the way they are at the start of experiment) at the same time and it is already saturated with them at the start of the experiment. This is a much more realistic case and this is when speed of adaptation is what matters most since it’s the only way for A and B to increase their numbers. For example an adaptation may allow them to utilize resources more efficiently, or give them access to new areas, or make them better at avoiding predators, etc, all ways to increase environmental capacity.
As for the reference, sorry, I can’t help you, but you are free to develop these ideas and publish them yourself if you so desire, scientific immortality awaits 😉
UH UH