Posted on 04/14/2004 6:15:04 AM PDT by 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.
Very Likely.
In fact, in the Middle East today that extinction is pretty much complete.
The difference, of course, is that Darwin's scientific theory was thorougly tainted by racism. I am not talking about any of the above's personal views or lifestyles. (Although I do grant that there is often overlap between personal beliefs and practices, and 'public' theory.) Jefferson's racism had nothing to do with the core of a scientific theory but Darwin's racism motivated the theory of evolution - in fact - evolutionism is inherently racist - the full title of Darwin's Origin of Species is rarely quoted by those who believe in the idea of evolution because it is obviously a racist theory and the title itself says so - The Preservation of Favoured Races in the Struggle for Life
When the theorist who theorizes does so out of a core of racial views and comes up with a so called theory that justifies his racism - this is quite different than saying that some, such as Jefferson, et. al. were racists.
Cordially,
Neanderthals were around for at least 250,000 years
See Ontology
Utilitarianism is mostly about political theory
See Utilitarianism and Utilitarian ethics
Cordially,
If the evolutionary progression of species in the Homo genus went from H. habilis, to H. erectus, to H. heidelbergensis (and other archaic sapiens), to H. sapiens (with neanderthal being an evolutionary dead end off of erectus), then the redhead gene = neanderthal is a false proposition (i.e. - you can't pass that gene along if you're extinct). If neandethalensis is just another archaic sapiens, then the differentiation of species is meaningless.
I don't see the "linkage" of the redhead gene to neanderthals by anything other than age. The distribution (as presently known) of neanderthal geographic range matches well with some of the redheaded cultures (Scots-Irish, Galacian Spanish, etc), but it also is coincident with dark-haired peoples, especially in the middle-east.
I still find it interesting that most "wild men" reported in history tended to be redheads.
Orangatangs?(sp) Maybe the red-head gene goes all the way back to the split with the 'apes.'?
I disagree. But, even if true, so what?
If the theory of evolution was instead authored by Abraham Lincoln, Grandma Moses, Bluebeard or the Emperor of Japan, how would that change the science behind it?
Well, now, in point of fact, I have noted that the atoms that comprise me, and the atoms that comprise you, have, in fact, produced differing beliefs about this matter. And yet, neither of us suddenly relocated through a hidden dimension to another time-space continuum. Furthermore, I deem it possible that either one of us might conceivably pursuade the other of the error of his current beliefs, and I further aver that if that happens, probably both of us will STILL be occupying this time-space continuum.
Call me an old stick in the mud, if you like.
See Ontology
Naturalism would have to be considered mostly a question in epistemology more than ontology. It is sort of a way of avoiding the issue(s) of ontology.
.Utilitarianism is mostly about political theory.
See Utilitarianism and Utilitarian ethics
Well, now, didn't I just gave you this reference in the wikipedia? Why are you echoing it back to me? If you don't mind, I'd just as soon not skitter all over the intellectual landscape if we can avoid it. Utilitarianism has little to do with ontology or epistemology, which is, putatively, the arena of this discussion. It a notion about what people ought to do, not how things are, or perception works.
It would seem strange to you. It seems to me like an ordinary turn of affairs like, for example, such apparently anti-entropic phenomenon as the weather, or snowflakes, or naturally occuring crystal formations, or stellar and planetary accumulations from homogeneously distributed dust.
Eh? That's all good and well, but in modern times, Darwin's fundamental theory falls out of general systems theory in mathematics as well. It doesn't matter if Darwin was a Grand Wizard of the KKK, the fundamentals of his theory have the backing of mathematics, so one can't trivially discard it as coming from an obviously biased source.
If you think Darwin's theory justifies racism, then that is your issue. Because regardless, you'll have the unwelcome task of disproving well-established mathematics if you want to discredit the fundamentals of Darwin's theory. (ObNote: This does not mean that evolution is the factual primary mechanism of speciation, only that it is a theoretically plausible and viable model, one of several possibles.)
You can't know this, in any ordinary sense. There cannot be a proof that an immaterial being did NOT interfere in the workings of a naturalistic universe, no matter how detailed and complete your knowledge of the material universe might be.
And, at any rate, even if this were true, there'd still be no way to know it, because you can't track down and account for all causal event chains in a quantum universe. A quantum universe has events that are apparently causeless, and random.
And, in fact, even if this weren't true, you'd still be up a crick without a paddle, because you couldn't possibly compute the future without a computer bigger than the universe. And even if that weren't true, you'd probably still be up a crick because of Godel's proof of the insufficiency of discrete systems to completely describe their domains of discourse.
So you're stuck with virtual free will, whether you like it or not--in fact, whether it's true or not.
Please enlighten me. I'm not sure what you mean by the fundamentals of Darwin's theory having the backing of mathematics.
Cordially,
I agree - you are exactly right, and I think you are on to something here, that finite knowledge limits "any" certainty, but only under a materialist premise. "Cannot know with any certainty" would only be correct only if there is no information from the "outside", which would be consistent with a materialist premise. Even an agnostic on the subject of certainty about such things is in essence asserting the contrapositive; namely, that there is not enough information to know the truth, an assertion I think fails because the agnostic has not searched and cannot search throughout the entire universe to know whether or not there is enough information. All I am saying is that the idea that all one's thoughts and propositions are nothing more than the result of cause and effect train of purely physical, chemical forces seems to be the logical conclusion that flows from the materialist premise.
So you're stuck with virtual free will, whether you like it or not--in fact, whether it's true or not.
Why virtual free will, and not determinism? [historical note: you may not believe this, but last night just before I went to sleep, the thought came into my mind out of the blue; "what would tortoise say about this issue?" This was before I came in this morning and saw your responses. And lo and behold, this morning I see tortoise's response to me (on another issue in this thread)in his post right before your latest posts.] We obviously think and act as if we have free will, but why else in your opinion, is 'virtual' free will the preferred conclusion, whether it's true or not, and not determinism? The reason I ask is that tortoise has stated in the past, and I'm paraphrasing here, that free will is an illusion, and that if we had the computing power we could prove it. Perhaps tortoise can back me up on this one:^)
Cordially,
All my other quibbles aside, If we had the computing power, we might, or might not, be able to prove it. Whatever formal system we use to demonstrate free will in the universe, will probably have to be powerful enough to demonstrate things about discrete quanta and discrete formal systems, even if it is, not, itself, a discrete formal system. Which seems immensely unlikely. If that is so, then Godel's proof demonstrates that there will be manifestations of the universe that can neither be proven or disproven. If free will hides there, then its certainty, or lack thereof, will be unknowable.
So...it might be true that we don't have free will because the universe exhibits closure under universal computation, but the odds, from where we stand, are so against it, that you can assume free will, and operate on that assumption, with virtual certainty. If you can't predict the future, it doesn't matter in the slightest, for the concerns of the day, whether or not free will is a matter of human mathematical denial, or inherent mathematical limits. The results are the same--assume free will--it will come up the winning number every time, whether it's true or not, which, from a naturalist's prespective, makes it a moot point of very distant concern.
Well, it more like IS the materialist's premise, so there's not a great deal of flow needed. More modern Godelian materialists, and materialists sensitive to the statistically random appearance of quantum-physical events, however, would still likely tell you that your computational plans are doomed to failure, and virtual free will prevails for all time.
Meaning that the process and model proposed by Darwin is a mathematically valid algorithm for generating the results he hypothesized would occur. The general model of biological evolution is an example of a class of system in systems theory, and is bound by those mathematical constraints (in the same way physics is).
To put it another way, given a dynamic system in which 1.) there is a selection process that is biased on average, and 2.) heritable traits vary between elements of the system, the mathematics of such a system pretty much requires that it express something analogous to both "speciation" and "evolution" in the biological sense. If you accept the two premises (and the two above seem extremely reasonable), the system is mathematically required to express something that is essentially "evolution".
The point that escapes most people is that while Darwin's specific model is technically correct in a rigorous sense, it is quite possible that a non-Darwinian set of system dynamics are actually generating most of actual "speciation" and "evolutionary" behavior that we actually see in the biosphere. The argument is often presented as a false dichotomy between Darwin's model or Creationism (of some flavor), when there can legitimately be several processes, including several "materialistic" processes, generating these outcomes simultaneously. In reality, there are probably one or two major mechanisms and a few minor ones as well that will fall below the noise floor for most intents and purposes. The hard part isn't showing that all these different mechanisms are valid, but determining which ones are the predominant mechanisms in the specific system that is earth's biosphere.
And in fact, there is growing belief in scientific circles that a classical strict Darwinian model (natural selection and random mutation) is probably a secondary mechanism for speciation and that other types of equally valid system dynamics are actually driving much of the change that we see, particularly in higher organisms.
donh explained it correctly; your paraphrasing of what I've said previously misconveys some of the essential elements.
Free will is "virtual" because a deterministic system within which we exist is incapable of expressing a deterministic analysis of said system. Or to put it another way, a deterministic analysis of our universe (and by extension, us) can only be done on an extra-universal computer that is larger (in an information theoretic sense) than our universe. So even if we are in fact deterministic, it would require a computer built from "unobtainium" to legitimately treat it that way. Since humans aren't such a computer, we cannot legitimately behave as though we are deterministic machines even if we are. Nothing within our universe is capable of perceiving the strict determinism of our nature.
But it isn't a functional distinction between "purely random" and "purely deterministic". A computer smaller than the universe, whether inside it or outside it, can still model a large system probabilistically within certain predictive limits, which is why we can still discern patterns within our universe even though our brains are a subset of the universe we live in. There is a whole subfield of mathematics that largely deals with the peculiarities and problems of modeling deterministic systems with pervasive predictive limits (e.g. non-axiomatic reasoning systems, algorithmic information theory).
Note that the above applies to all finite state systems and a subset of all non-finite state systems. There are strong reasons to believe that our universe (and us by extension) fall within this set of possible systems e.g. our universe exhibits properties that are mandatory within this set of systems but which should not be exhibited exclusive of this set. (Interestingly, Alamo-girl's constant questions and grilling on these matters led me to figure out that there were classes of non-finite state systems that could and should be included for theoretical purposes.)
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