Instinct in Evolution

I think we see them in ourselves but I'm not the expert on the topic. Why, where I live, are a lot of people "instinctively" terrified of spiders when the worst of them here will give you a small sore bump? However, they are not afraid of cars or undercooked hamburger. At least not in the same way.Is it possibly because were we evolved and left only a few hundred generations ago it is a very good thing to keep away from spiders?If there are vestigial instincts and if this fear isn't taught then this is one.

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Common sense isn't

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If "evolution is continuous", that would mean that every organism, without exception, has vestigal instints (remnants of prior instints that at one point were usefull, but as a result of lack of use, have faded away). More-over, every organism should also have evolving instincts... an array of instints that have no purpose, but that do not hinder them. I am no expert in animal behavior, so if anyone is, please post your thoughts. If vestigal, or evolving instints are not found in nature, then the current concept of evolution, as I said before, is flawed.

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I am not an expert in animal behavior, but one possible vestigial instinct can be seen in domestic dogs. Dogs display a nesting technique before they lie down, that is they circle around a few times before lay down. This is seen in every breed. This instinct can be seen in wolves, who cirlce around in the snow in order to make a bed for themselves. Therefore, this instinct if seen in dogs that can not or do not live in arctic conditions can be considered vestigial. Circling around on the rug in front of the TV does little to provide a bed, but in the snow it is very adventageous.

Not to be too picky...but I think that the fear of spiders (and snakes, too, for that matter) is a learned behavior. At least, that's what I was taught.As far as vestigial instincts go, I suppose one could put forth the argument that many courtship behaviors and threat displays are "vestigial" (ie:ritualization). They haven't "faded away" as Adsent Minded suggested they would have, but instead have evolved into exaggerated forms of other behaviors and now have a "new" function. I guess that this doesn't fit the purest definition of vestigial, but hey, I'm just throwing out ideas here. Besides, (as crashfrog pointed out), how would you identify a vestigial behavior if it is no longer performed?

Hmmm... Interesting responses... in their most part however, I have no need to respond to, as you will notice a little bit ahead. Continuing my train of thought from yesterday, this is to me a strong reason for considering TOE to be flawed:Premise: Evolution is a process in which natural selection, random mutation, and chromosomal differences take part in shaping the outcome of the next generation usually in such a way as to be unperceivable to the naked eye. It is not "purposeful" as genes have no will of their own, but it is continuous so even today it is still ongoing. (Since this is a premise on which my next few points will touch, feel free to correct it.)Now, what exactly is considered a mutation? DNA is composed of Adenine, Guanine, Cytosine and Thymine, which are C5H5N5, C5H5N5O, C4H5N3O, C5H6N2O2 respectively, and in addition Adenine always pairs up with Thymine, and Guanine with Cytosine... one cannot be found in a properly formed DNA structure without the other. Taking into consideration that absolutely no hormone or protein or any part of any organism can be changed (Instincts are included here), we have to now figure out, what is considered a "mutation, when we talk about the DNA structure. Are the mutations caused by radiation in the form of: Alpha (2 Protons and 2 Neutrons - +2 charge, highly ionizing slow, and not able to penetrate far), Beta (about the size of an electron and have high penetrating power) or Gamma (no mass and no charge, they affect atoms by super-exciting them and causing them to lose mass, ... in other words, turning them into different materials.) Obviously, none of the radiation sources mentioned above can be responsible for any of the main components of DNA to be added to a DNA chain in any of its trillions of units. If anything, when exposed to even the smallest amount of radiation, what would happens is that a gene, hence a hormone or protein, will fail to be produced, and the resulting organism would just be adversely affected (ex.: Lack of a pigment gene resulting from radiation exposure would change an organisms color to one not readily found in nature, or going a bit more extreme, lack of the "eye genes" because of exposure to radiation causes an organism that usually comes with eyes, to be born without them.)What other methods of "mutation" exist? Chemical Mutagens. For the most part, these types of mutagens, if they do not destroy the cell, cause DNA lesions. DNA damages (a.k.a., lesions) tend to be chemical modifications of nitrogenous bases that prevent in some manner their recognition by DNA polymerase and, indeed, stop DNA replication from occurring at the point of the lesion. This can be "fixed" by the cell, by bringing about the other pair. (EX.: if Adenine is missing, but the complementary Thymine is still there, the cell will do its best to replace it with another Adenine... if not, cell death occurs) So this other type of mutation, still doesn't allow for proper addition of AGTC to any part of the DNA strand.One more point: What amounts of steady (non-cell killing) mutations are needed for TOE to hold true? "...evolution doesn't just "leap forward" (that would almost never work - the probabilities are just too low), all evolutionary paths have to be *continuous* - i.e., there must be a progression of tiny steps in which each step leads to a more advantageous result given the current environment that the species is living in." -Rei If Rei's statement is true, evolution is continuous, and hence, we ALL have to be constantly changing from one generation to the next. Not counting the effects of chromosomes (flip, cut, paste, whatever it is would not account for the immense variation and changes if mutation is not true) the entire world would have to be bathed in a mutagenic concoction and our cells would have to be working overtime at repairing and replacing long strands of DNA and all the while, chromosomal flips and copies and the such keep occurring...Ouch.. Sorry, but I just re-read what I had in that last paragraph, and I would like to rephrase it in a way that would sound more sensible:1. TOE states that all organisms "evolve" and change over time, and that these changes are a result mutation, chromosomal activities, and natural selection working in conjunction over millions (billions) of years, in a steady pace, depending on the environment and the organisms' needs.2. When taking DNA into consideration, Adenine, Thymine, Cytosine and Guanine are its main components, and when affected by mutagenic elements, Adenine, Thymine, Cytosine and Guanine are not produced, but in fact are destroyed, making an existing gene not present itself, or, if the cell manages to fix the detrimental gene, the cell reverts back to the way it was before the mutagenic element was introduced.3. A combination of a mutagenic element, chromosomal copy, flip and such, combined with the cells' ability to repair itself, seems to be the only viable way for "new" Adenine, Cytosine, Guanine, and Thymine, to be added to the original DNA strand, and if the cell is able to survive, and the replication subsystem of the DNA was not damaged, AND if the cell affected was one that will eventually be used for procreation of life, then that change will be passed on to the next generation. The "new" material, as small as it may be, has no guarantee to ever be used, unless it is used in the formation of an already existing protein, in which case the final outcome of that protein is iffy at best. And the parents' experiences through life (except mate selection) in no way affect what genetic changes happen to the new organism.4. If these changes have to occur in a "steady pace", then step 3 has to occur pretty often, even over billions of years, for changes to occur.5. Since large amounts of mutagenic elements would have been needed over those billions of years, and (I am not a geologist here, so I am going on a limb) they are/were not present: The original statement that Evolution consists of changes caused by mutation and chromosomal activities coupled with natural selection over billions of years, is flawed, for lack of occurrences (or even the possibilities of occurrences)The above logic does not take into consideration the incredibly low probability that the same cell that was exposed to the mutagens was also a cell destined for reproduction, and that the change caused in the cell on one of its genes, is not detrimental (mutagens and chromosomal flipping cannot be assigned purpose... they are just random. So that factors in too.) And that the protein/chemical that it makes, is able to express itself eventually. Also, how much of the above steps would have to happen (how many generations of animals) would it actually take for 1 particular protein/chemical to manifest itself in some way?"...evolution doesn't just "leap forward" (that would almost never work - the probabilities are just too low), all evolutionary paths have to be *continuous* - i.e., there must be a progression of tiny steps in which each step leads to a more advantageous result given the current environment that the species is living in." - ReiCouple that with the fact that instinct is also supposedly handled in the same way as the physical features of an animal (how long will it take for the above change to actually affect an instinct?).I tried to place my thoughts as simple as possible... but I am Absent Minded, so I may have missed a few things, or explained things in such a way that people follow it wrong. So I will be very attentive to any comments posted after this, and will reply at my earliest convenience (not today, need to catch up on work).

Mutagenic substances are not necessary for mutations to ocurr. Sometimes simple copying mistakes are made when the DNA replicates.Anyway, you seem to be arguing that mutations should be rare. They are not. Mutation rates can be measured in the laboratory, even without mutagenic substances. You have several mutations not shared by either of your parents.

Any genetic sequence that you didn't inherit from either of your parents. The cause is not important. No, and no one's saying they are, directly. What happens is that ionizing radiation or some chemicals break DNA chains, and the cellular mechanisms that repair DNA are not perfect - sometimes they insert new genetic sequences. Only if you assume the cellular mechanisms are perfect. They're not, of course, so these other types of mutation can add novel genetic material too. Right, that's the mistake. Cellularrepair mechanisms are not perfect. Mistakes are made even in simple DNA transcription and duplication. I don't understand how you conclude this. Every day we're bathed in ionizing radiation from the Sun and from fissionables in the Earth's crust. Not to mention various organic compounds capable of genetic damage. And mutations happen all by themselves, during normal cellular processes. In fact some organisms can even scale up their rate of mutation in response to envrionmental stresses.

It's not picky at all. The difference between learned and instinctive in this case is important. If learned then I'm wrong in my conjecture.

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Common sense isn't

Hmmm... interesting proposals. But it just brings up 1 very interesting point:I. If the one way that DNA mutations occur is through the cells own "relatively deficient" repairing skills, then what caused the mutations before those repairing skills were around?Unless these were automatically part of all biological organisms when they came about, I really don't see how change in cells through faulty copy is DNA repair is possible.Also: "Every day we're bathed in ionizing radiation from the Sun and from fissionables in the Earth's crust." - Crashfrog.True, but you fail to note that the "Ionizing Radiation" from the sun doesn't have enough penetrating power after going through our atmosphere (specially our ozone layer which was stronger before the modern pollution began to rip it apart), and fissionables are not things that common for evolution to be driven by it... I mean, what are more common, precious metals, or radioactive metals?"Not to mention various organic compounds capable of genetic damage." - CrashfrogThis statement particularly interested me because: before modern science, what were these organic compounds? This is an honest question on my part, since I do not know of any naturally existing organics that can cause mutation."... mutations happen all by themselves, during normal cellular processes." -Crashfrog. The very first point I make is in reference to this."In fact some organisms can even scale up their rate of mutation in response to environmental stresses." -CrashfrogTHAT I would like to see. If any type of evolution is almost impossible by definition to observe, how can "mutation", beneficial or not, be purposely increased by organisms that are not aware of how their cells work, or cells that are not aware of the "big picture". By your own definition, you are ascribing purpose to a process that by definition has none.Again, thanks for the replies. I will come back to see if any more have been posted.

Mutations would have happened during copying as well, as they do now. You can't have life without the ability to copy genetic material. That's a basic condition for life. As long as that copying process is not perfect - and there's no reason to assume it ever would be, for a few reasons - there will always be evolution, because that imperfect copying is a source of mutation. Oh, it gets through. A high-energy gamma ray is going to punch right through the atmosphere, ozone and all - and potentially pop right through one of your chromosomes. Ozone doesn't even stop all of the ultraviolet that it's supposed to absorb. It's not perfect, and I doubt it ever has been.Why do you think there's a connection between solar exposure and skin cancer? How common do you think it has to be? There's a considerable background hum of radiation on the Earth's surface. Anyway, the cell's own imperfect copying is the source of enough mutations. All kinds of stuff your body generates or that you might eat. Free radicals can damage DNA. Here's an article from PubMed:

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Naturally occuring mutagens.

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Clark AM.

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Naturally occurring mutagens have usually been discovered as a result of outbreaks of disease in agricultural livestock, or as a result of epidemiological studies of cancer of the liver in man. Subsequent work has then shown that the toxic agents responsible often have mutagenic properties. Examples are the pyrrolizidine alkaloids, cyasin, a range of mycotoxins produced by various fungi, and at least two unidentified toxic agents in bracken. Commonly the toxic agent itself does not show high biological activity, but after ingestion it is converted by metabolic processes into the active mutagen or carcinogen. Some of these toxic substances have been responsible for considerable losses of agricultural livestock and therefore are of economic significance. From the view-point of genetic hazards to man, the most significant compounds are probably the mycotoxins, e.g. aflatoxin, because of the common risk of fungal contamination of food, especially in tropical regions. No information is yet available on the effects of these mutagens on natural populations of animals. Plants containing the pyrrolizidine alkaloids are found in areas of Africa and the Middle East where plagues of the migratory locust occur. Although it is known that some of the alkaloids can induce chromosomal damage in grasshoppers, whether such damage ever becomes a significant factor under ecological conditions is not known. In some cases, insects have not only evolved resistance towards mutagenic alkaloids but have become dependent on them for certain purposes. The males of certain Danaid butterflies feed on plants containing pyrrolizidine alkaloids. After ingestion, the alkaloids are metabolised to dihydropyrrolizine derivatives, which are then secreted on special organs (hair pencils) and, following dissemination into the atmosphere, act as pheromones for the stimulation of mating behaviour.

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From Naturally occuring mutagens - PubMedYou misunderstand. They're not deciding to do it - it's not voluntary, any more than the changes your own body undergo in preparation for winter are voluntary. (You retain more water, gain weight, and sleep more.) It's an automatic cellular response to certain changes in the environment. Not so. I'm simply saying that in response to environmental conditions that a cell could concievably be affected by - starvation, drought, etc - biochemical processes are put into place that tend to increase the number of mutations during cell division. As this could conceviably have a survival advantage, it's reasonable that we would find it in some organisms.

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Stationary phase mutagenesis: mechanisms that accelerate adaptation of microbial populations under environmental stress.

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Kivisaar M.

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Department of Genetics, Institute of Molecular and Cell Biology, Tartu University and Estonian Biocentre, 51010 Tartu, Estonia. maiak@ebc.ee

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Microorganisms are exposed to constantly changing environmental conditions. In a growth-restricting environment (e.g. during starvation), mutants arise that are able to take over the population by a process known as stationary phase mutation. Genetic adaptation of a microbial population under environmental stress involves mechanisms that lead to an elevated mutation rate. Under stressful conditions, DNA synthesis may become more erroneous because of the induction of error-prone DNA polymerases, resulting in a situation in which DNA repair systems are unable to cope with increasing amounts of DNA lesions. Transposition may also increase genetic variation. One may ask whether the rate of mutation under stressful conditions is elevated as a result of malfunctioning of systems responsible for accuracy or are there specific mechanisms that regulate the rate of mutations under stress. Evidence for the presence of mutagenic pathways that have probably been evolved to control the mutation rate in a cell will be discussed.

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Again, from PubMed: Stationary phase mutagenesis: mechanisms that accelerate adaptation of microbial populations under environmental stress - PubMed

Just to add another reference to what crash wrote:Kirschner M, and Gerhart J, 1998 "Evolvability", PNAS 95:8420—8427

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Evolvability is an organism’s capacity to generate heritable phenotypic variation. Metazoan evolution is marked by great morphological and physiological diversification, although the core genetic, cell biological, and developmental processes are largely conserved. Metazoan diversification has entailed the evolution of various regulatory processes controlling the time, place, and conditions of use of the conserved core processes. These regulatory processes, and certain of the core processes, have special properties relevant to evolutionary change. The properties of versatile protein elements, weak linkage, compartmentation, redundancy, and exploratory behavior reduce the interdependence of components and confer robustness and flexibility on processes during embryonic development and in adult physiology. They also confer evolvability on the organism by reducing constraints on change and allowing the accumulation of nonlethal variation. Evolvability may have been generally selected in the course of selection for robust, flexible processes suitable for complex development and physiology and specifically selected in lineages undergoing repeated radiations.

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What the article says is, literally, natural selection can select for increased variability by selecting genomes and processes that are more error-prone. IOW, the evolution of evolvability. {You may be able to find this article on line at the Proceedings website. If so, it's well worth the read and explains a lot of the concepts you seem to have questions about.)[This message has been edited by Quetzal, 01-13-2004]

In a similar vein one of the predisposing factors for cancer or first steps in nonhereditary cases is posession of mutator, or microsattellite instability, sequences which exhibit high levels of genomic instability. As these are highly unstable populations they can quickly give rise to phenotypes allowing for rapid expansion of the population and subsequent metastatic invasion of other tissues, fitness in cancer cell terms. Similarly non-msi associated cancers also frequently demonstrate genomic instability. And a related article on the possible role of mutator phenotypes in eukaryotic evolution. These articles are both available in full text online so I have not included any abstracts.

Very interesting posts. Could you (Crashfrog, or others following this) please give me some references as to how cell copying occurs. I am really interested in seeing how simple that process is... after all, how complex can it be if EVERY cell in existance (and even viruses when inside a cell) needs it to even exist.During my own searches, I found it way too complicated to arise on its own (http://www.karlloren.com/biopsy/p66.htm), but I am sure you have a simpler process in mind, that could hold true in origin times.

I googled and got this first, it was quite interesting: No webpage found at provided URL: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/D/DNAReplication.htmlI don't exactly understand how you come to such a conclusion. Well, I'm not a biologist, so no, I really don't. I guess I have a few suspicions but they're founded entirely on my own ignorance. For instance I find the example of prions very intriguing - protein strands that are able to catalyze other protiens to take on the prion shape. Not exactly self-replicating, of course. My suspicion is that the first "living" molecule was a protien of such simple construction that it could rely on natural processes to join naturally-occuring amino acids. Then the protien would act on these natural polypeptides, catalyzing them to take on the new shape. Perhaps this occured inside of naturally occuring membranes at first; later, the protien would have been able to catalyze them as well.Now, how we get to RNA/DNA after that, I don't know. It's a major survival advantage, so it shouldn't be a major leap. And of course we're hampered by the fact that molecules don't leave fossils. Like I said, I'm not a biologist. Doubtless there's much wrong with my scenario.

The actual primary process of evolution is movement. 4.5 billion years ago something started to 'move itself'. Evolution is a proces, processes are in motion, and that 'moving around' creates evolution. So, instincts and behavior initiate the evolutionairy proces. To make the proces progressive you need to pass over the best genes. To ensure the survival of the best genes you need to regulate the motions or behavior. The fact that effectively all lifeforms must first mature before they can procreate is one of the reasons that life evolved progessively. The proces of life was 'triggered' into action. The energy from that trigger is still with us, its called hunger.

Welcome to the fray, QuibusPlease note that the post you are replying to is over a year old, and as such the person may no longer be visiting the site.Try |All Topics| in the header to get a list of the latest topics to see if there is one that interests you.

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