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"But it is real, lots of people have it"

Discussion in 'General Discussion' started by Juice, Apr 9, 2011.

  1. bewildered

    bewildered
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    Typically someone who doesn't believe in evolution believes that everything was created as it is now ~6000 years ago. The small-scale genetic changes that certain species experience over time, they claim, is not evolution. Usually the sticking point is the age of the earth, because if the earth really IS ~5 billion years old, then there is plenty of time for these small scale changes to snowball into differentiated species. You're usually better off debating the age of the Earth, because that is their main "fact" that holds up their disbelief of evolution.

    Of course, there are other avenues of argument, but this is a lot of times the sticking point.
     
  2. MoreCowbell

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    This strikes me as unlikely. Somewhat lengthy science nerdery in spoiler.

    This seems to display a common fallacy that people fall into with evolutionary thinking. The mere fact that a species or group has a trait and that the species had undergone evolutionary natural selection does not mean that the particular trait in question was subject to any sort of selectionary pressure. To be blunt, some things are evolutionary accidents, such as the human appendix (what evolution scholars call a vestigial structure).

    The reason that women have better color vision is because they have two alleles of a trait that codes for certain types of photoreceptor cells, whereas men have one. This is a consequence of them having two X chromosomes, and us having one.

    Women's color vision is probably not a direct product of natural selection as such, but is rather what evolutionists refer to as a "spandrel." This is basically the unintended consequence of some other genetic/evolutionary fact, the same way that one gets a spandrel when one joins a dome with an arch in architecture.

    For it to be a product of natural selection, there would have to be a group of females without this particular trait. As this is impossible without supposing females with only one X chromosome, the trait seems to lack the differentiated subgroups that are a basic prerequisite for selectionary evolution.

    Odds are that evolution selected for differentiated sex chromosomes for some other reason, and color vision advantages came along for the ride.
     
  3. bewildered

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    It is true that certain traits are evolutionarily neutral. However, your example of a vestigial structure is not a very good example of this. Vestigial structures may not be useful to us TODAY, but they were at some point. It takes more than a couple mistakes in the genome to create a whole working structure in the body.

    The appendix (since it is vestigial, this is of course mostly theory) is theorized to be a "re-seeding area" of the intestines.

    Our intestines are full of bacteria that aid in digestion. In the slim possibility that you ate something bad and had massive diarrhea for days and somehow survived, most of that useful bacteria would have been flushed out and you probably would die from something related to that. The appendix is kind of a dead end street that is not on the main road of the intestines. It allows a little growth of bacteria to be untouched by cases like severe diarrhea. Your entire intestines can be reseeded from this small bacterial growth in the appendix.

    On the other hand, this structure can get things caught up in it and become closed off and infected, causing other problems. Since the quality of food today is much safer than when we were foraging in the woods for fruit and game, it is not needed as much and causes more harm than good.
     
  4. $100T2

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    Not really a debate, but definitely a misunderstanding where I thought I was being clever and she just didn't fucking get it:

    I was dating a deaf girl, and once we were in her bedroom and she did that trick girls do where they remove their bra without removing their shirt. So, she's basically in a t-shirt with naked boobs underneath.

    I slyly sign, "Hey, you should change your shirt now, too," with a big grin on my face. Now mind you, we've basically been living together, fucking like rabbits, etc, so you'd think she'd get the idea that I'm suggesting her shirt come off to lead to fondling and sex.

    Instead, she gets really, really pissed off.

    "What's wrong with my shirt? I think it looks great!"

    It led to a half hour argument where I had to explain my subtle hint, and her still thinking I didn't like her shirt.

    Just so you all know, subtlety, sarcasm, double entendres, shit like that is 100% lost on deaf people. You must be 100% literal at all times. "Your bra is off. Take your shirt off too, because I want to play with your tits then bang you" would have saved me a half an hour of grief.
     
  5. LessTalk MoreStab

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    I'm going to have to disagree, although you make a nice argument. If the adaptation is beneficial the chances that it only locked in by chance or piggyback is tiny. Any trait which provides an improvement provides and advantage, in a species as homicidal and genocidal as homo-(whatever we were at the time), any advantage could easily see groups or individuals without that advantage taken out of the evolutionary game.

    Anyone know of any tests of other primates eyesight? Would be interesting to see if the colour management system was the same in all primates or if we as homo sapiens differ. Would solve the argument immediately.
     
  6. bewildered

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    I'm going to chime in here and agree.

    A lot of the neutral genetic changes that you originally alluded to are usually in the form of junk DNA or inactive regions of the chromosome. Considering the staggering amount of data that is encoded in your genes, only a small amount of those bases actually are used to create proteins. On top of that, the error rate during mitosis and meiosis is incredibly low. On the chance that there is an error, there is a chance that the error will be fixed, and if not fixed, the error will code for the SAME amino acid anyhow (a "silent" mutation).

    Secondly, you talk about X linked inheritance with your example of color blindness. Since this is a recessive trait, it tends to skip generations, but nevertheless, it is quite common. As common as it is, if it were negative, it would long ago been mostly squashed out. So, as far as natural selection, it is either viable or simply neutral.

    Thirdly, there is a huge variety of different types of color blindness influenced by different genes. Your argument that it was a gene piggybacking as part of some other trait is flawed when you consider this. Why would there be so many varieties of this trait if it were simply neutral or "piggybacking"? There must be some advantage to it for there to exist so many occurrences of it.

    As far as I know, cases of genetic piggybacking are fairly rare. There is enough genetic material in your genome to code for the proteins and products that your body needs to survive. There are overlaps where introns and exons can be separated in unique ways to create unique products, but that is different than what you were describing.
     
  7. Harry Coolahan

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    There is such a thing as externalities when it comes to genetics and evolution, you know...