Hi root. Maybe the problem is that you are thinking of these mutations as being something bad in the short term. I don't think evolution is meant to work like that. A change would have to be neutral or give an advantage if it was going to stay around for long. It wont always be possible to see at this distance in time just what the small advantages for each small step may have been. Another thought. I think someone mentioned flying squirrels. I guess you've seen them on documentaries leaping out of trees and all. The way I imagine it you have an ordinary squirrel, it lives in trees and it jumps around. Branch to branch and all that. Now suppose some of these squirrels have just a little bit more loose flesh, so that when they jump they can go a little further, or don't need to push off so hard, so they get by on one less nut in a winter. They are a tiny bit more successful than there pals, so they have fractionally more kids, and so on. A mutation gives some of those kids even looser flesh. They wind up more successful. And so on. Before long you have flying squirrels. Doesn't that seem likely to you?
indeed... Otherwise take webbed feet of birds. It's fairly simple to change from webbed feet to not. Should it be difficult to change to webbed hands then (bats)? Similarly there is a frog that glides through air. All it did was enlarge the skin surface between its digits. It could already benefit from the webbing between its fingers when it was jumping. Increasing the surface just increased the effeciency.
Yes, I am saying that if "Natural Selection" through "Survival of the Fittest" was the only driving force then it can't be like that. I think that is quite a logical deduction, there has to be some other driving force for Evolution. As far as I know it is accepted that birds did develop from some Dinosaur-like animals walking on their hind legs. If we then take a hypothetical case of such an animal that changed into a bird over a period of, lets say, 100000 years and, for simplicity sake, consider each 20000 years of its development then please explain: How at each of these steps can this animal be better equipped for survival than a normal one without any change. or, tell me: How can I change the scenario to make it more acceptable?
No, you cannot say that. What you want to say is that there was one point in the fossil record when what were similar to what we now call horses, and what evolved into what we now call horses, would have been and are called something else. A breed, as in a dog breed, is a subspecies. The definition of a species is when two animals have diverged apart to the point when they can no longer breed together and reproduce to have offspring. Avians or Aves (birds) and Dinosaurs both evolved from Reptiles. The origin of flight started gradually and there are many different kinds of flyers: leaping, parachuting, gliding, flapping, soaring, diving, hovering. There are a few theories. One theory is that feathers evolved initially in birds for insulation: flight came later. First they were ground dwelling, then tree dwelling. You can imagine how feathers would have then facilitated the function of a bird first leaping about up into the air, then parachuting down from a tree, then gliding from one tree to another, then flapping motion combined with the now-adapted aerodynamic shapes of the wings inabled it to have active flight. The second theory is that birds evolved from dinosaurs. One dinosaur called Microraptor gui had feathers on all four limbs. Another Dinosaur bird called Archaeopteryx had teeth, bird-like perching claws, and wings like modern-day birds. The evolution of flight would have probably been the same as that described above. Finally, another theory is that webbed feet on reptiles evolved into feathered wings. Imagine how flying squirrels today use the folds between their legs to glide from tree-to-tree. Similarly, these webbed feet would've enabled the reptile to glide easier. This theory is unlikely, but again, the basic stages in the evolution of flight would have been the same as described above.
That's interesting. What sort of force do you think this might be? I thought these could be possibilities: 1) There seems to be a tendency in Nature for things to organise. We see this at the smallest scale, with quarks and such organising into neutrons and protons, and at the largest scale with matter organisign itself into stars and galaxies. And superficially all this organisation seems to fly in the face of the Laws of Thermodynamics. So, maybe this 'evolutionary force' is just a tendency to organise. 2) Maybe Lamarck was right and there is some way, sometimes, that the lifestyle of an organism can influence its genetic character. 3) Life has been placed here by aliens and the major developments at least are somehow precoded into our DNA, or are introduced in some way at a later time. 4) A creator intervenes periodically to start life off in new directions. 5) ??? Do any of these strike a chord with you? Or would you add another possibility?
By reading what biologists already wrote about it and incorporating this information and speculation in it..
It is very hard to have a reproducing organism that flies apart all the time. Organization might be an effect of life but does that make it a cause? The genetic constitution of sperm will surely suffer if you keep a block of plutonium in your pocket environment. However, Lamarck is all about passing on changes in form to the next generation, because the form is supposed to influence the genetics of the reproducing germline. That clearly has never been shown to exist. I have never seen any evidence for that. By sending a meteor down to the surface of the planet? It's all a bit far fetched isn't it if you can explain these phenomena by natural means.
Hello Spurious, I'm not sure what you are wanting to show. Root said he thought evolution had some other driving force. So, I offered a menu of some I could think of, without a chef's recommendation. Please Register or Log in to view the hidden image! I am interested in which of these (or other alternative) root sees as offering a better explanation than evolution by natural selection. That might help us identify which aspect of the natural explanation is most difficult for him to take on board. By the way, I was surprised by your take on organisation. Don't most of the experts in this area believe that is the self-organising characteristics of certain organic molecules that would have led to the first self replicating molecules? Perhaps, I have this wrong though. Now that we can do genome sequencing and the like quite easily, wouldn't it be possible to set up an experiment that would demonstrate that Lamarkian inheritance doesn't happen, not just that is has never been observed?What do you think? And if the creator is all powerful she might just reach in and tweak a DNA strand or two directly? Please Register or Log in to view the hidden image!
Let's list then the current 'acceptable' driving forces in evolution: 1. Natural selection (well supported) 2. Sexual selection (idem) 3. Genetic drift (a favourite with many) hmmm...what else is there? 4. physiological restrictions???? ---- About the self-organization. Yes, indeed, you are quite right, self organization of molecules could well have started the first organisms. But I would say that the organization of any current form of life is well beyond this kind of 'auto'-organization. Life is mainly putting lots of energy into building and maintaining form. This form will start disappearing immediately once the state of life has passed into the state of death. Is it therefore a current driving force? I seriously doubt it. But you are quite right to speculate that it might have given the incentive to life. I hadn't really thought about the origin of life in this particular discussion because it is so speculative.
I was a bit loose in my previous post. Sorry. Trying to keep it brief, often turns out the other way, like shopping. I was slightly aware of the sexual selection and genetic drift mechanisms, but was lumping them for convenience under the flag of Natural Selection, really to mean conventional evolution. Definitely need more self discipline! Root doesn't seem to like any of the conventional explanations, so I wanted to 'root out' what he thinks might be a viable alternative. I was mainly thinking of the origin of life for the self organisation, then conventional evolution takes over. I wonder though, whether we have not now reached a further level of self organisation. As we begin to manipulate our genes to 'improve' our offspring (and ourselves), could that not be considered a very high level of self organisation? If you agree, then let me take it one step further. If we got the galaxies and stars and planets as a result of the tendency of matter to self organise, and life got started through self organising molecules, and the next step in self organisation stem from the conscious actions of intelligence, then it leaves a gap. Evolution is the only thing in that whole sequence that doesn't involve self-organisation. It would be more attractive, I don't know, more beautiful, if there were some kind of self organising mechanism at work there too. I guess that sounds very mystical, and whimsical, and decidedly unscientific, but I do sometimes feel there is just something missing in the whole evolution picture that an as yet unrecognised principle of self organisation could address. Please don't ask me what it is. If I could answer that I would already be en route to Stockholm to collect my prize. Please Register or Log in to view the hidden image!
Well, i'm not going to ask you...don't worry... I would like to remark that conventional evolution is actually a radical idea. All the other 'non-accepted' forces that keep being mentioned to death are actually mostly really boring in my view. They have been repeated over and over (lamarck anyone?), and can they really beat 'conventional' evolution in intracy and beauty? I would say no.
I wouldn't start contributing evolution to a force unless you want to involve religion here and please don't, cuz you know where that's going to lead to. Evolution is a gradual change and is the result of random mutations in the genome that result in a change in an organism from generation to generation. These random mutations may eventually allow a part of a population of organisms to become better suited to its environment, and then those are the populations that survive (Natural Selection and Survival of the Fittest): the others become extinct if their changed environment becomes so extreme that they cannot adapt to it. One thing you mentioned was "there seems to be a tendency in Nature to organize...at the smallest scale." I paraphrased what you said to emphasize that this organization IS at the smallest scale: the micro scale. At the macro scale we see no such organization except perhaps for planetary bodies being attracted by the force of gravity to become part of an orbital system. According to the Second Law of Thermodynamics, not all energy can be used, some is lost, and disorder increases. When energy is used in a reaction or metabolic process, some energy has to be always lost. This applies to all energy transformations. So on a macro scale, while we as mere small humans see organization at the micro scale, ultimately this organization uses up energy and the end result is disorder and disorganization. This is best seen on the macro universal scale: galaxies are spread apart in so many different forms, we have black holes, the universe is expanding, the existence of antimatter, and on top of all this, I believe the current estimate is that we can only account for about 5% of the matter in the universe. The other 95% is still under speculation and current theory on that matter involves "worm holes" in the universe with multiple dimensions - I think it's 15 dimensions. Not sure? But if you want to get into a discussion about this then you really should start a new thread, and probably sciforum already has one under the astronomy category as this would not be part of biology.
Although we do not know exactly what lineage modern day birds evolved from. There is no question that the development of wings was beneficial. Some dinosaurs had feathers but did not fly. Their wings served to provide protection for their young by blocking the wind, rain, and providing insulation. Have I answered your question(s) yet?
Well...the people who study what is called General Evolutionary Theory, or Evolutionary Systems Theory (not well known, but they include Ilya Prigogine, Jonas Salk, Ervin Laszlo, Eric Chaisson, Ralph Abraham, others) might say yes. They would argue that a feature of all complex systems amidst rich, fluctuating flows of energy, and with multiple potential trajectories, is a tendency for a reorganization of relationships in order to work more efficiently, or else face the demise of entropy and devolution. This is true not only in biological systems, but in cosmological systems, physical systems, cognitive systems, and social systems. So amidst a background of entropy,there is a "negentropic" spiral, an upward race for efficiency in organization in response to fluctuations in available information and energy, and the emergence of life in the cosmos was no mistake. It's important to update your knowledge. The very concept of evolution has evolved. For example, there is an effort to clarify Darwin's thinking - www.thedarwinproject.com. I think one part of that is that he didn't actually mean "survival of the fittest," but "survival of the fit." And that stuff was really not the biggest emphasis in Darwin's thinking, but moreso cooperation. I'm not sure. Check out the site. Evolution can be seen as a creative force pervading the universe. This is not a religious statement, since it does not imply a "being who" is wielding the force. But it certainly has implications...It suggests that if the people who are promoting "intelligent design" would agree that evolution is an intelligent force but NOT vested in a God-like being, and if the scientists who believe that evolution is a series of "accidents" that lead to life would see it as much more intelligent than accidental, then we might have an end to that conflict. But not likely, since neither body is probably willing to shake up their worldviews.
Why should lfe have knowledge of possibilities. Evolution is as much about the death of the least fit, as the survival of the fittest. More imporantly what is "fit" is constantly changing - it is what is fit for the hear and now. For me Evolutionary pressure is more like water - finding the route of least resistance, in effect the best fit. Like a river evolution meanders into different niches. It is a cultural conceit to see a direction and purpose and man at the top of the tree. It could well be argued that ants or cockroaches are better models of pinnacles of evolutionary direction, or even the flu viruses. I mentioned in my first post to this that yours was a favourite creationist question - do you favour that point of view?
When I started this thread I was genuinely under the impression that there is a known other force at work in evolution and I just wanted to know what it is. I don't proclaim that I know, to me it just so damn obvious that "Survival of the fittest" cannot adequately account for all the development in life. I think the problem with the people that is advocating this theory is that they are looking at great steps in development, requiring 100000 of years, and then it looks plausible. For example these statements: Feathers came first and then wings, or Early wings could be used for cooling or for balancing, or Flying animals first glided and then learned to fly. This all sounds great but how long does it take to get to each of these points. I am talking of the minute changes from one generation to the next, how many of these changes would there be in the full development of flight, lets say 100000. I cannot see that each one of these 100000 minute changes provided the animal with sufficient benefit to out-reproduce those without the changes. Is this so difficult to see, they say there is no one so blind as those who do not want to see. Maybe Genetic Drift, as was mentioned in some replies, could account for this, I am not sure exactly what it is though, I would have to read up on it. I am not going to reply to anymore letters as I don't think I can attribute any further, I do however notice that there are still some interesting conversations going on.
To some people (like me) it is 'obvious' that selection can adequately account for the diversity of life. I think once again that your brain just needs some time of contemplation. That's normal. Natural selection sounds easy on paper but actually people find it hard to grasp in reality. Always has been this way and will properly always be. Take some time to search the real literature (that is scientific articles in proper journals) on the small problems. You may think nobody tried to explain some of these things like the appearance of wings. But I think you will be surprised. Lots haven't been inevstigated, but that is merely because the amount of evolutionary details in almost infinite and the amount of researchers in this field very finite. Sometimes just one or a few generations. Sometimes long. I don't really believe in the capacity of genetic drift to produce detailed form. It merely eliminates options and guides ruighly in my humble opinion.
Take out the word "pressure" when you state "evolutionary pressure is more like water" and you got it right. We cannot predict the flow of each molecule of water - although in general, water follows the path of least resistance - as it occurs as a result of random collisions of atoms, like in Brownian Motion. Again, evolution is not a force: it is an occurrence in Nature that results in a gradual change with continuity from generation-to-generation. It is a steady gradual change toward an adaptive direction. At the core of evolution are the random mutations that are the ultimate source of genetic variation: evolution is a cumulative genetic change. If you start talking about "intelligence" behind this, then you're either referring to a god, or getting into a circular argument. As to how long evolution takes, sometimes it occurs very quickly, as we are seeing right now in the mutations that develop into new strains of the Avian Bird Flu virus, while others occur over millions of years, as we can determine from the fossil evidence of animals. "1. Natural selection (well supported) 2. Sexual selection (idem) 3. Genetic drift (a favourite with many)" None of these are forces and they are all quite unrelated. Genetic drift occurs when a "small" population of animals becomes restricted in size from the original large population. This small population then has less of a variety in types of genes to use for evolution (the allele frequency in the gene pool is reduced). Genetic drift is also the result of chance mutations but because it restricts the size of the gene pool, these mutations are also restricted and can lead to favorable mutations that allow the animal to survive, or unfavorable mutations that cause extinction. We are seeing many unfavorable genetic drifts today that are resulting in extinction and "endangered species." Genetic drift is the reason that the Passenjer pigeon and the Dodo bird became extinct - we decreased the size of their original large population by hunting so many of them that there were no longer enough to breed successfully to produce offspring with enough variation to survive. This is also happening right now with Panda Bears in China, Rhinos in Africa, and cougars in Florida (only about 50 left).
In genetics and evolution the word "forces" does not have the same meaning as you are using the word in this forum. In general conversations you normally think of a force as an active power, or pushing, or an energy that "causes" something to happen. Then you get into philosophical arguments about cause and effect. In genetics we use the word forces to refer to "evolutionary processes" like mutations, random chance, and recombinations. Probably the most often quote you hear regarding "forces" in evolutionary theory is: "natural selection is the driving force behind evolution." Nowadays it is commonly thought that thermodynamics is the driving force behind biological evolution and astrophysic theories. You can contrast this to the definition of force used in physics. There are four fundamental forces in Nature: electromagnetism, gravity, the strong nuclear force, and the weak nuclear force. It's just kind've important to realize that there are these different ways of defining and classifying, and then using the correct terminology according to the context of the subject, or else you get into misunderstandings and unnecessary arguments. For example, if you start to think of a force in evolution as being some type of supernatural power, then your getting into the subject of religion and philosophy and not scientific evolution. To get a more detailed explanation about how they classify and categorize forces, you might want to check out the explanations given in the Wikepedia at: http://en.wikipedia.org/wiki/Force
