Just been watching a very interesting episode of Horizon on genetics. It appears that genes aren't actually the only unit of heredity. Apparently it is starting to appear as if it's possible for what you do in life to have an effect as to which genes are expressed in your children and grandchildren.
Experiments have shown that exposing a mouse to a pesticide can mean that it's grandchildren suffer from certain diseases even if they aren't exposed to the toxin even though no mutations have occured.
Pretty interseting I thought so I decided to share.
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Interesting.
So what does this do to the previously defunct evolutionary theory that giraffes got long necks by stretching them to eat higher leaves?
So what does this do to the previously defunct evolutionary theory that giraffes got long necks by stretching them to eat higher leaves?
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Giraffes evolved longer legs to reach higher leaves. They evolved longer necks so that they could still drink while doing it
Seriously though, the reason why I mentioned Lamarck is because he was behind Lamarckism which is pretty much the theory you describe (that actions of one individual creature can be passed on to descendants and that this acts as another force driving evolution rather than just mutation and natural selection).
Lamarckism is generally considered incorrect because genetics doesn't work the way it needs to in order for it to work. Just because a giraffe stretched its neck doesn't mean that it can somehow transcribe that information into his genes so in the vast majority of cases there isn't any way to pass the longer neck on to the descendents except by waiting for the suitable mutation to arise naturally.
What this seems to show is that in some cases a gene can be switched off in future generations due to some environmental factor that affected the parents.
The example they gave in the show was if a mother had been through a famine during puberty she'd have a smaller birth canal. In order to actually be able to give birth her body would throw epigenetic switches in the child to make it be born younger or with a smaller head at birth. The interesting part is that this is a heriditory change. The grnadchildren will also be born with smaller heads too even if their parents never experienced a famine.
So it looks like although Lamarck was wrong in the vast majority of cases there are a few times when his theory can have a short term effect.
The effect on overall evolution is probably minor. Given a few hundred thousand years you'll probably see the switches get flicked on and off so often that their effect averages out.
Seriously though, the reason why I mentioned Lamarck is because he was behind Lamarckism which is pretty much the theory you describe (that actions of one individual creature can be passed on to descendants and that this acts as another force driving evolution rather than just mutation and natural selection).
Lamarckism is generally considered incorrect because genetics doesn't work the way it needs to in order for it to work. Just because a giraffe stretched its neck doesn't mean that it can somehow transcribe that information into his genes so in the vast majority of cases there isn't any way to pass the longer neck on to the descendents except by waiting for the suitable mutation to arise naturally.
What this seems to show is that in some cases a gene can be switched off in future generations due to some environmental factor that affected the parents.
The example they gave in the show was if a mother had been through a famine during puberty she'd have a smaller birth canal. In order to actually be able to give birth her body would throw epigenetic switches in the child to make it be born younger or with a smaller head at birth. The interesting part is that this is a heriditory change. The grnadchildren will also be born with smaller heads too even if their parents never experienced a famine.
So it looks like although Lamarck was wrong in the vast majority of cases there are a few times when his theory can have a short term effect.
The effect on overall evolution is probably minor. Given a few hundred thousand years you'll probably see the switches get flicked on and off so often that their effect averages out.
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I find it hard to believe in such memory effect that would work with only via the experiences of the earlier generations.
Though IMHO it is likely that some residues might still present in say four generations after the exposure to the what-ever-causes-the-effect. Like from non-water soluble pesticides (or other stuff, PCBs etc.) that accumulate to living systems. Same goes for some metallic compounds (like some platinum containing cancer drugs) that can cause severe problems in genes by binding quite strongly to nucleotides... So there might be a link with this kind of exposure to the memory effect.
There is also no reason why there couldn't be self synthesized compounds that would work in the same way (stress related), those compounds would be present only in very low amounts and therefore very hard to identify.
Though IMHO it is likely that some residues might still present in say four generations after the exposure to the what-ever-causes-the-effect. Like from non-water soluble pesticides (or other stuff, PCBs etc.) that accumulate to living systems. Same goes for some metallic compounds (like some platinum containing cancer drugs) that can cause severe problems in genes by binding quite strongly to nucleotides... So there might be a link with this kind of exposure to the memory effect.
There is also no reason why there couldn't be self synthesized compounds that would work in the same way (stress related), those compounds would be present only in very low amounts and therefore very hard to identify.
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I've got to say that I find it rather hard to believe myself and it is a source of some contraversy but the evidence does appear to be fairly strong for something so new.
While I'll admit that I can see the possibility of low levels of metals or pesticides having a teratogenic effect like you describe the concentration of that toxin (and therefore the strength of its effect) has to go down with the number of children born. If a rat has 20 children then I'd expect each to get 1/20th of the toxin. By the fourth or 5th generation we'd have very tiny amounts but the studies showed similar levels of the effect. If the problem was simply due to the toxin remaining in the system a few more generations would reduce the levels to homeopathic levels and the effects on the animals would disappear.
It's not just the experience that is causing the effect. Scientists think that something is turning a switch on or off. Once that has been done the switch stays in that state until something switches it back on again. The next challenge (and the thing that would get me to really believe all this) is finding what that switch is.
While I'll admit that I can see the possibility of low levels of metals or pesticides having a teratogenic effect like you describe the concentration of that toxin (and therefore the strength of its effect) has to go down with the number of children born. If a rat has 20 children then I'd expect each to get 1/20th of the toxin. By the fourth or 5th generation we'd have very tiny amounts but the studies showed similar levels of the effect. If the problem was simply due to the toxin remaining in the system a few more generations would reduce the levels to homeopathic levels and the effects on the animals would disappear.
It's not just the experience that is causing the effect. Scientists think that something is turning a switch on or off. Once that has been done the switch stays in that state until something switches it back on again. The next challenge (and the thing that would get me to really believe all this) is finding what that switch is.
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IIRC one of the other examples Lamarck used (or wanted to; I forget which) would be that if a blacksmith had big muscles, then his son would too, as a direct result.
So... obviously the difference here is that Lamarck was (IIRC) essentially proposing that genes would change in response to individuals physical state (i.e. the blacksmith would just have and pass on this dominant muscley gene), whereas this is really about the controlling of which genes are active.
Which I think is something of an ongoing area of study; I vaguely remember an anecdote about using mouse(?) eye genes inserted into the DNA of a fly; which then grew a correct fly eye. The likely reason being that there was something which controlled how/which genes were expressed, and that this used (not in the intelligent sense, in the happy coincidence type sense) the commonality between fly and mouse eye DNA codes to create a proper fly eye. Or something like that.
And..bugger, I missed that Horizon
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So... obviously the difference here is that Lamarck was (IIRC) essentially proposing that genes would change in response to individuals physical state (i.e. the blacksmith would just have and pass on this dominant muscley gene), whereas this is really about the controlling of which genes are active.
Which I think is something of an ongoing area of study; I vaguely remember an anecdote about using mouse(?) eye genes inserted into the DNA of a fly; which then grew a correct fly eye. The likely reason being that there was something which controlled how/which genes were expressed, and that this used (not in the intelligent sense, in the happy coincidence type sense) the commonality between fly and mouse eye DNA codes to create a proper fly eye. Or something like that.
And..bugger, I missed that Horizon
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I felt the same disappointment when I missed the one on human hobbits a few weeks back. Partly because it sounded interesting but mainly because it looked like Horizon were just itching to give Channel 4 another black eye over their science programming
I've heard the example of the blacksmith before. To be fair to Lamarck he did predate Darwin so there is no reason to believe he wouldn't have simply agreed with Darwin had he been given the chance to hear Darwin's theories.
Partly because it sounded interesting but mainly because it looked like Horizon were just itching to give Channel 4 another black eye over their science programming I've heard the example of the blacksmith before. To be fair to Lamarck he did predate Darwin so there is no reason to believe he wouldn't have simply agreed with Darwin had he been given the chance to hear Darwin's theories.
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Yeah, I forgot what it was called. Stupid of me not to catch on to the thread title.karajorma wrote:Seriously though, the reason why I mentioned Lamarck is because he was behind Lamarckism which is pretty much the theory you describe
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Speaking of turning established science on its head there's an interesting article here. Apparently some guy believes he's come up with a method for making heat from water in a manner that is cheaper than any current method.
Only problem is that it breaks the rules of quantum physics to do it.
Apparently he claims he can break the orbital of a hydrogen atom and force it to move the electron closer to the nucleus (a lower energy state) and form what he calls a hydrino.
All the critics say that he's talking boll##ks and he's gotten his maths wrong but unlike more crackpots he does appear to have gotten some favourable peer review on this one.
Very odd. He claims that he's almost readyt to go live with this though so if he is correct he'll have to prove it soon.
Only problem is that it breaks the rules of quantum physics to do it.
Apparently he claims he can break the orbital of a hydrogen atom and force it to move the electron closer to the nucleus (a lower energy state) and form what he calls a hydrino.
All the critics say that he's talking boll##ks and he's gotten his maths wrong but unlike more crackpots he does appear to have gotten some favourable peer review on this one.
Very odd. He claims that he's almost readyt to go live with this though so if he is correct he'll have to prove it soon.
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I'm just starting on quantum physics right now, but I'll agree that this sounds pretty fishy to me. That article's right in saying that scientists are a pretty conservative lot when it comes to accepting new theories, and this has caused problems in the past. However, I think that any theory that turns a hundred years of progress, experimentation, and research on its head has to be greeted with more than a little skepticism, especially if only one person is claiming that such a theory exists. The concept of "quantized" energy regarding electrons is one of the fundamentals of subatomic physics, and in my opinion, if you're going to make claims like this, you'd better have a hell of a lot of hard evidence to pass around; from what I understand, this guy really doesn't have that. It's true that things like Einstein's special theory of relativity were seemingly born out of nothing (Einstein didn't even know about the Michaelson-Morley experiments that disproved the idea of "ether," nor did he use the Lorentz-Fitzgerald contraction; his paper in 1905 contained no outside references), but it came about because he saw a fundamental conflict between Newtonian physics and the relativity principle. I don't see any such conflict existing here, so unless this guy can prove otherwise, I'm viewing this as cold fusion all over again.
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And that's what it has to be. I don't know quantum physics well enough to say whether this is possible or impossible. TBH, even if I did, I'd probably come down on the side of impossible just because I don't like massive change. But even if this guy can produce just his little household heater, then he's clearlyon to something worthwhile. Good luck to him."If it's wrong, it will be proven wrong," said Kert Davies, research director of Greenpeace USA. "But if it's right, it is so important that all else falls away. It has the potential to solve our dependence on oil. Our stance is of cautious optimism."
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Exactly Black Wolf. Extrodinary claims require extrodinary proof but the way science is treating this claim is exactly the way they should. Lots of people think he's wrong but they let him publish and use peer review to see if he's wrong or right. So much for the claims of people who say that science won't change cherished theories if new evidence that disputes them comes to light.
That said am I the only person wondering what the properties of these hydrinos would be? Cause they do sound interesting and would almost certainly have different chemistry from hydrogen (lower enrgy state so they'd be less reactive, give out less heat when they do react etc).
Part of me does want him to be right. I've never much liked the seperation between Newtonian and quantum physics anyway. Despite all the evidence for the difference it always struck me that things might be easier if we're simply missing something
That said am I the only person wondering what the properties of these hydrinos would be? Cause they do sound interesting and would almost certainly have different chemistry from hydrogen (lower enrgy state so they'd be less reactive, give out less heat when they do react etc).
Part of me does want him to be right. I've never much liked the seperation between Newtonian and quantum physics anyway. Despite all the evidence for the difference it always struck me that things might be easier if we're simply missing something
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The guy claims that what we thought was the lowest stable orbit was only the second lowest and there there is one much more stable.
I do find that hard to believe but there has been peer review on his work and apparently it hasn't all claimed that he is wrong.
I do find that hard to believe but there has been peer review on his work and apparently it hasn't all claimed that he is wrong.