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JaKiri

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Posts posted by JaKiri

  1. Small nitpick, what you describe does not necessarily qualify evolution.

     

    That's perfectly true.

     

    This is a little bit hard for me to swallow. Even if they were mining families for a lot generations, what actually happened? Did all taller children die in the mines?

     

    Yeah, it's natural selection at its finest. The tallest people didn't get shorter, they just didn't breed (back problems, more likely to killed* in mine accidents, whatever).

     

    *I saw this in a study done for a Miner's Gala in Durham a few years ago. I won't be able to find a copy and can't find it online, so we can ignore this one if you like.

     

    Anyway, it's a fairly noticeable example - I grew up in the north east, and the taller members of the community were from families that had either moved there from elsewhere or were traditionally middle class or better.

  2. It was necessary to drop the second bomb. Directly targeting two seperate cities is a verification that, yes, it is us who are doing it.

     

    Don't forget it's not just American casualties that were saved; the Japanese would have created enormous, underarmed, civilian militias, and the casualties there would have been incredible.

     

    One thing I am taking away from this thread is a reaffrimation of how bad pacifisim really is.

     

    You are a pacifist (Einstein) and work toward world peace. Some nut job is bent on killing a lot of people and he steals your bank account. Then you realize that maybe pacifism probably isn't the best course of action (Einstein).

     

    I am keeping my arsenal in the hopes of never having to use it instead of being unarmed and needing the weapons.

     

    What a load of tosh.

  3. To have a noticable change it would take a very long time, I'm talking tens of thousands of years, right?

     

    Not necessarily. It could be hundreds, or less. It could be a week, if we're talking about a situation where most things die out suddenly.

     

    The people in Africa who are immune to malaria, can that be classed as evolution? It was passed down from generation to generation over a very long time.

     

    Yes, although the reasoning behind it is a bit overzealous.

  4. Yeah' date=' they hoped to kill pathogens via osmosis.[/quote']

     

    If that's an interview question, I suspect the aim of it is to test the methodology of the student when asked something that's unlikely to be known already, an independent problem, rather than whether someone just gets the right answer out.

     

    Yey! Tell the Cambridgeans I'm on my way... to Oxford.. :P

     

    Cantabrigian.

  5. But how do we evolve? Will we grow fur if our environment suddenly becomes colder (IceAge)? :confused: Grow fur, grow gills...something like that...mutate?

     

    Mutation is the name of the game. (Things in brackets are examples, and not necessarily the sole examples)

     

    Mutations are not directed, they are random. They involve the change of a small part of the genetic code, either by external action (the action of radiation) or by a simple copying error. Both of these are happening fairly regularly in everyone, but most of the time they don't get expressed; the gene isn't a relevent one (part of junk DNA), or it is "caught" by one of the myriad of backup systems the body has in place. However, quite often they slip through.

     

    And, by and large, do very little.

     

    However, they can cause problems; changes can be either big or small, depending on precisely what bit of the genetic code changes. A very simple mutation in the fruit fly drosophila (in the HOX genes, to be precise) can cause legs to grow where its eyes should be. However, the really really bad ones are generally weeded out - they are "deleterious" - because if they have bad adaptations, they're less likely to breed and pass on this trait to a new generation.

     

    However, if they're good (or merely "mediocre" - this can include "bad" changes - autism is a possible example, because nowadays being autistic is not as unlikely to cause one to not pass on genes as it was in days gone by, whilst still arguably having a negative affect on the person with the condition) they may well be passed on, and, if sufficient people get the genes, or if there is a big advantage to having them, then they will get fixed in the population. However, genes which have no large "positive" to them can also be lost, by a process called genetic drift, which it isn't necessary to go into.

     

    So what we have is a system of random mutations which can, possibly, make the thing carrying them more or less likely to breed. If they're more likely to breed, due to breeding faster, being better suited to gather food or whatever, then the population may well change.

     

    This is natural selection.

     

    It's all about passing genes onto your offspring, and evolution is the change in these genes over time, from one generation to hundreds.

     

    One thing you will note, however, is that the changes are fairly small. The example with the fruit fly above is a strange case, because such an important part of development was controlled by a single, small, set of genes.

     

    Most changes, like, say, developing functional gills, would require so much alteration of the genetic code that for it to happen through sheer random chance (which is how the mutations arrive; whether they stay in society is, partially, not random, but what mutations arise in the first place is entirely random) is so unlikely to be nearly impossible.

     

    Good examples of human evolution is the gradual change in brain size over the last thousand to hundred thousand years, or the tendency in North East England of mining families, who had to work in cramped environments underground, to produce smaller children even with a similar diet to their taller classmates.

     

    Evolving to a catastrophe is rare, extremely rare, and generally requires the ability to survive the castrophe to have existed in the population beforehand; a good example is bacteria attacked by antibiotics. There's a chance that some of the bacteria will already, randomly, be resistant to the antibiotic in question and so they will survive and the others will die, and so in the next generation nearly all of the bacteria will be resistant to the antibiotic. This is part of the reason why "superbugs" evolve; the other is that when you don't finish your treatment of antibiotics, there's a chance that some of the bacteria, who aren't resistant to the antibiotic, will have survived; they breed fast, and, in an environment when there's still antibiotics hanging around, there will be a big advantage to the bacteria who happens to randomly acquire a resistance to the antibiotic - so if that mutation appears, it will fast become fixed in the population, and you have the infection back, but this time resistant to whatever you used on it before.

     

    This doesn't always happen of course; sometimes the bacteria just die out without having randomly mutated a resistance to the antibiotic. Think of this kind of extinction event to be similar to a board game. You land on a space that says "throw a 6 to continue", except in this case you have a hundred dice, and have to roll a 6 on all of them.

  6. Welcome to 'Politcial Correctness.' Creation Science isn't just about God creating the Universe and all life. There're other theories in CS that are also dealt with. Like aliens 'seeding' the planet.

     

    They're not theories, they're postulates. Actually, they're not even that.

     

    And it's not science, because it doesn't "do" science. "The sciences" are a group of subjects which use the scientific method.

  7. Time is a David Bowie song.

     

    In a more sensible answer: it's a pointless question. "Time" is a concept that's not made up of anything else, just like you can't break "length" or "mass" down into other measures.

  8. Forgetting about the "odds." Is it possible that evoluition is a direct result of a superior being (note how I don't say suprime being). And that even evolution is controled by said superior being, instead of everything you just said. Is it possible? Yes. Is it likely[/i']? No.

     

    That's "Intelligent Design", not "Creationism".

  9. Utter bo SHIT! OK this ticked me of...yes' date=' it may be logical to you but to me, its only partially logical. How life first began seems to me only partially logical and macroevolution to me also gives me som skepticism.

     

    Nothing in science is a fact except "nothing in science is a fact".[/quote']

     

    Read > Comprehend > Post.

     

    "Evolution" is not "the theory of evolution", you dingus, it's a process. "A logical concept" is not "a concept which makes sense", it's "a concept which can be proven to exist by logic".

     

    Now, if I just said "Evolution is a logical concept", there might be some grounds for misunderstanding. But when there's an entire other sentence clarifying what exactly I mean, you really don't have any excuse. Furthermore, even if I hadn't made that distinction, it would still be true, because the process has been observed to take place, and any theory that comes along must take it into account.

  10. I'm not really sure what you want for the Force/acceleration graph. Both the force and the acceleration are constant in magnitude, and, with respect to eachother, in direction. That is, the graph of the force vector (ie, the force in a given direction) will be a sine curve. The graph of the accelration vector (similarly) will be a sine curve. The same sine curve. So plotting one against the other just gets a straight line of F vs a (or, more properly, F/m vs a, if you want to take variable masses into account).

     

    fmagraph8xu.jpg

     

    If you plot it with F vs a, then all you can find out is the mass, from F = ma. If you plot it as F/m vs a, then all you can find out is that F = ma.

     

    "Mass vs Distance" I'm utterly confused about, as it appears to have no meaning at all.

     

    massline2yh.jpg

     

    Unless you mean weight, in which case it'll be a hyperbola.

  11. ok. what evidence, and can you say for an ESTABLISHED FACT that evolution is true?

     

    "Evolution" is a logical concept which is utterly, utterly true. It's not even just "science true" like gravity or the existance of sunlight.

     

    Further to this, it's been demonstrated to exist in computer simulations, bacterial cultures (how do you think "superbugs" get created if not by evolution?), innumerate numbers of insects, horses, dogs, cats, fish, man, apes, trees, strawberries and sea anemones, both historically and since we've been studying the process.

     

    Lets have an example. In the North East of England, there had been decades, centuries, of coal mining. Coal mining involves being placed in cramped spaces, 14 hours a day - either low, but, for most, walkable-under, ceilings (in the well trafficed areas) or areas, such as the coal face, where you had to crawl.

     

    And you know what? Coal miners, from mining families, tended to be shorter than the rest of the populace around them. Of course, this could of course have been diet, but even today, when there are no pits in County Durham, and the mining families have transferred into all walks of life (the former chairman of Northern Electric came from a mining family, fior example) people from miners' families, and their offspring, tend to be shorter.

     

    That, by definition, is evolution. Whether or not its the evolution of Darwin, Lamarck, or something better, is not the point. Evolution does exist, and the only argument that can take place is over the mechanism.

     

    as for 6, it is based on the majority.

     

    It's a rather overly wide statement, and an inflammatory one - neither of which are really desireable on this forum - the former in a conceptual sense of a "science" forum, the latter in a more general sense of a science "forum".

  12. Pulling the arrows out of the body might be a bit gruesome, mind you, but you'd have to, to leave no evidence.

     

    I think the fact that I was quoting someone talking about the problems of firing ice from guns might have suggested to you that I was talking about firing ice from crossbows.

  13. tripic3gt.jpg

     

    AF:AC = AD:AB and FAD = BAC, so the triangles ABC and ADF are similar. Therefore the angles phi and theta are the same, so DF is parallel to BC.

     

    Similarly, DE is parallel to AC (and therefore to AF) and EF is parallel to AB (and therefore to AD. As the opposite sides of our quadrilateral as parallel, it's therefore a parallelogram.

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