Louis VI the Fat
03-20-2010, 17:00
So the Darwin year has drawn to an end.
The appreciation of Darwin has gone through ups and downs over the last 150 years. Presently, hist stature is: first there was darkness. Then there was the Big Bang of 'The Origin of Species'. The Best Idea Ever. The foundation of biology, all later biology has been filling in the blanks and writing the footnotes. What's more, biology is moving from a hobbyist 'postage stamp collecting' kind of science into a central cientific discipline, with Darwianian/ 'modern synthesis' thought as its central paradigm.
But...what if Darwin was wrong?
What's more, what if it is of merely academic interest whether Darwin was right or wrong, but that the more devastating conclusion is that Darwinian evolution is not the most relevant way to understand life to begin with? Could our most basic understanding of life turn out to be a mere product after all of lingering Victorian British thought?
1 - Lamarck was right after all. :knight:
Lamarck's general principle that lifestyle might be able to influence heredity has been scorned ever since that British amateur naturalist rose to prominence. Today any high school student knows that genes are passed on unchanged from parent to child, and to the next generation and the next. Lifestyle cannot alter heredity.
Except now it turns out that it can:
Take, to begin with, the Swedish chickens. Three years ago, researchers led by a professor at the university of Linköping in Sweden created a henhouse that was specially designed to make its chicken occupants feel stressed. The lighting was manipulated to make the rhythms of night and day unpredictable, so the chickens lost track of when to eat or roost. Unsurprisingly, perhaps, they showed a significant decrease in their ability to learn how to find food hidden in a maze.
The surprising part is what happened next: the chickens were moved back to a non-stressful environment, where they conceived and hatched chicks who were raised without stress – and yet these chicks, too, demonstrated unexpectedly poor skills at finding food in a maze. They appeared to have inherited a problem that had been induced in their mothers through the environment. Further research established that the inherited change had altered the chicks' "gene expression" – the way certain genes are turned "on" or "off", bestowing any given animal with specific traits. The stress had affected the mother hens on a genetic level, and they had passed it on to their offspring.
The Swedish chicken study was one of several recent breakthroughs in the youthful field of epigenetics, which primarily studies the epigenome, the protective package of proteins around which genetic material – strands of DNA – is wrapped. The epigenome plays a crucial role in determining which genes actually express themselves in a creature's traits: in effect, it switches certain genes on or off, or turns them up or down in intensity. It isn't news that the environment can alter the epigenome; what's news is that those changes can be inherited. And this doesn't, of course, apply only to chickens: some of the most striking findings come from research involving humans.
One study, again from Sweden, looked at lifespans in Norrbotten, the country's northernmost province, where harvests are usually sparse but occasionally overflowing, meaning that, historically, children sometimes grew up with wildly varying food intake from one year to the next. A single period of extreme overeating in the midst of the usual short supply, researchers found, could cause a man's grandsons to die an average of 32 years earlier than if his childhood food intake had been steadier. Your own eating patterns, this implies, may affect your grandchildren's lifespans, years before your grandchildren – or even your children – are a twinkle in anybody's eye.
It might not be immediately obvious why this has such profound implications for evolution. In the way it's generally understood, the whole point of natural selection – the so-called "modern synthesis" of Darwin's theories with subsequent discoveries about genes – is its beautiful, breathtaking, devastating simplicity. In each generation, genes undergo random mutations, making offspring subtly different from their parents; those mutations that enhance an organism's abilities to thrive and reproduce in its own particular environment will tend to spread through populations, while those that make successful breeding less likely will eventually peter out.
As years of bestselling books by Dawkins, Daniel Dennett and others have seeped into the culture, we've come to understand that the awesome power of natural selection – frequently referred to as the best idea in the history of science – lies in the sheer elegance of the way such simple principles have generated the unbelievable complexities of life. From two elementary notions – random mutation, and the filtering power of the environment – have emerged, over millennia, such marvels as eyes, the wings of birds and the human brain.
Yet epigenetics suggests this isn't the whole story. If what happens to you during your lifetime – living in a stress-inducing henhouse, say, or overeating in northern Sweden – can affect how your genes express themselves in future generations, the absolutely simple version of natural selection begins to look questionable. Rather than genes simply "offering up" a random smorgasbord of traits in each new generation, which then either prove suited or unsuited to the environment, it seems that the environment plays a role in creating those traits in future generations, if only in a short-term and reversible way. You begin to feel slightly sorry for the much-mocked pre-Darwinian zoologist Jean-Baptiste Lamarck, whose own version of evolution held, most famously, that giraffes have long necks because their ancestors were "obliged to browse on the leaves of trees and to make constant efforts to reach them". As a matter of natural history, he probably wasn't right about how giraffes' necks came to be so long. But Lamarck was scorned for a much more general apparent mistake: the idea that lifestyle might be able to influence heredity. "Today," notes David Shenk, "any high school student knows that genes are passed on unchanged from parent to child, and to the next generation and the next. Lifestyle cannot alter heredity. Except now it turns out that it can . . ."
2 - Evolution is mostly horizontal
Even more devastating is the notion that genes do not just pass from parent to offspring, but between organisms.
What's more, evolution itself may have changed from horizontal to vertical. Vertical evolution merely a stage in an evoultion that evolves.
We've learned that huge proportions of the human genome consist of viruses, or virus-like materials, raising the notion that they got there through infection – meaning that natural selection acts not just on random mutations, but on new stuff that's introduced from elsewhere. Relatedly, there is growing evidence, at the level of microbes, of genes being transferred not just vertically, from ancestors to parents to offspring, but also horizontally, between organisms. The researchers Carl Woese and Nigel Goldenfield conclude that, on average, a bacterium may have obtained 10% of its genes from other organisms in its environment.
To an outsider, this is mind-blowing: since most of the history of life on earth has been the history of micro-organisms, the evidence for horizontal transfer suggests that a mainly Darwinian account of evolution may be only the latest version, applicable to the most recent, much more complex forms of life. Perhaps, before that, most evolution was based on horizontal exchange. Which gives rise to a compelling philosophical puzzle: if a genome is what defines an organism, yet those organisms can swap genes freely, what does it even mean to draw a clear line between one organism and another? "It's natural to wonder," Goldenfield told New Scientist recently, "if the very concept of an organism in isolation is still valid at this level." In natural selection, we all know, the fittest win out over their rivals. But what if you can't establish clear boundaries between rivals in the first place?
And what to make of recent developments in human-controlled genetic tinkering? Strides in scientific progress have enormous philosophical consequences for the thought of evolution as a random process.
3 - Ann Coulter is smarter than Darwin.
The American rightwing noisemaker Ann Coulter makes the point in her 2006 pro-creationist tirade Godless: The Church of American Liberalism. "Through the process of natural selection, the 'fittest' survive, [but] who are the 'fittest'? The ones who survive!" she sneers. "Why, look – it happens every time! The 'survival of the fittest' would be a joke if it weren't part of the belief system of a fanatical cult infesting the Scientific Community.":
Jerry Fodor, the American philosopher. Fodor's objection is a distant cousin of one that rears its head every few years: doesn't "survival of the fittest" just mean "survival of those that survive", since the only criterion of fitness is that a creature does, indeed, survive and reproduce.
As far as I can make out, it can be summarised in three steps. Step one: Fodor notes – undeniably correctly – that not every trait a creature possesses is necessarily adaptive. Some just come along for the ride: for example, genes that express as tameness in domesticated foxes and dogs also seem to express as floppy ears, for no evident reason. Other traits are, as logicians say, "coextensive": a polar bear, for example, has the trait of "whiteness" and also the trait of "being the same colour as its environment". (Yes, that's a brain-stretching, possibly insanity-inducing statement. Take a deep breath.) Step two: natural selection, according to its theorists, is a force that "selects for" certain traits. (Floppy ears appear to serve no purpose, so while they may have been "selected", as a matter of fact, they weren't "selected for". And polar bears, we'd surely all agree, were "selected for" being the same colour as their environment, not for being white per se: being white is no use as camouflage if snow is, say, orange.)
Step three is Fodor's coup de grace: how, he says, can that possibly be? The whole point of Darwinian evolution is that it has no mind, no intelligence. But to "select for" certain traits – as opposed to just "selecting" them by not having them die out – wouldn't natural selection have to have some kind of mind? It might be obvious to you that being the same colour as your environment is more important than being white, if you're a polar bear, but that's because you just ran a thought-experiment about a hypothetical situation involving orange snow. Evolution can't run thought experiments, because it can't think. "Darwin has a theory that centrally turns on the notion of 'selection-for'," says Fodor. "And yet he can't give an account – nobody could give an account – of how natural selection could distinguish between correlated traits. He waffles."
Link (http://www.guardian.co.uk/science/2010/mar/19/evolution-darwin-natural-selection-genes-wrong), with further links at the bottom.
The appreciation of Darwin has gone through ups and downs over the last 150 years. Presently, hist stature is: first there was darkness. Then there was the Big Bang of 'The Origin of Species'. The Best Idea Ever. The foundation of biology, all later biology has been filling in the blanks and writing the footnotes. What's more, biology is moving from a hobbyist 'postage stamp collecting' kind of science into a central cientific discipline, with Darwianian/ 'modern synthesis' thought as its central paradigm.
But...what if Darwin was wrong?
What's more, what if it is of merely academic interest whether Darwin was right or wrong, but that the more devastating conclusion is that Darwinian evolution is not the most relevant way to understand life to begin with? Could our most basic understanding of life turn out to be a mere product after all of lingering Victorian British thought?
1 - Lamarck was right after all. :knight:
Lamarck's general principle that lifestyle might be able to influence heredity has been scorned ever since that British amateur naturalist rose to prominence. Today any high school student knows that genes are passed on unchanged from parent to child, and to the next generation and the next. Lifestyle cannot alter heredity.
Except now it turns out that it can:
Take, to begin with, the Swedish chickens. Three years ago, researchers led by a professor at the university of Linköping in Sweden created a henhouse that was specially designed to make its chicken occupants feel stressed. The lighting was manipulated to make the rhythms of night and day unpredictable, so the chickens lost track of when to eat or roost. Unsurprisingly, perhaps, they showed a significant decrease in their ability to learn how to find food hidden in a maze.
The surprising part is what happened next: the chickens were moved back to a non-stressful environment, where they conceived and hatched chicks who were raised without stress – and yet these chicks, too, demonstrated unexpectedly poor skills at finding food in a maze. They appeared to have inherited a problem that had been induced in their mothers through the environment. Further research established that the inherited change had altered the chicks' "gene expression" – the way certain genes are turned "on" or "off", bestowing any given animal with specific traits. The stress had affected the mother hens on a genetic level, and they had passed it on to their offspring.
The Swedish chicken study was one of several recent breakthroughs in the youthful field of epigenetics, which primarily studies the epigenome, the protective package of proteins around which genetic material – strands of DNA – is wrapped. The epigenome plays a crucial role in determining which genes actually express themselves in a creature's traits: in effect, it switches certain genes on or off, or turns them up or down in intensity. It isn't news that the environment can alter the epigenome; what's news is that those changes can be inherited. And this doesn't, of course, apply only to chickens: some of the most striking findings come from research involving humans.
One study, again from Sweden, looked at lifespans in Norrbotten, the country's northernmost province, where harvests are usually sparse but occasionally overflowing, meaning that, historically, children sometimes grew up with wildly varying food intake from one year to the next. A single period of extreme overeating in the midst of the usual short supply, researchers found, could cause a man's grandsons to die an average of 32 years earlier than if his childhood food intake had been steadier. Your own eating patterns, this implies, may affect your grandchildren's lifespans, years before your grandchildren – or even your children – are a twinkle in anybody's eye.
It might not be immediately obvious why this has such profound implications for evolution. In the way it's generally understood, the whole point of natural selection – the so-called "modern synthesis" of Darwin's theories with subsequent discoveries about genes – is its beautiful, breathtaking, devastating simplicity. In each generation, genes undergo random mutations, making offspring subtly different from their parents; those mutations that enhance an organism's abilities to thrive and reproduce in its own particular environment will tend to spread through populations, while those that make successful breeding less likely will eventually peter out.
As years of bestselling books by Dawkins, Daniel Dennett and others have seeped into the culture, we've come to understand that the awesome power of natural selection – frequently referred to as the best idea in the history of science – lies in the sheer elegance of the way such simple principles have generated the unbelievable complexities of life. From two elementary notions – random mutation, and the filtering power of the environment – have emerged, over millennia, such marvels as eyes, the wings of birds and the human brain.
Yet epigenetics suggests this isn't the whole story. If what happens to you during your lifetime – living in a stress-inducing henhouse, say, or overeating in northern Sweden – can affect how your genes express themselves in future generations, the absolutely simple version of natural selection begins to look questionable. Rather than genes simply "offering up" a random smorgasbord of traits in each new generation, which then either prove suited or unsuited to the environment, it seems that the environment plays a role in creating those traits in future generations, if only in a short-term and reversible way. You begin to feel slightly sorry for the much-mocked pre-Darwinian zoologist Jean-Baptiste Lamarck, whose own version of evolution held, most famously, that giraffes have long necks because their ancestors were "obliged to browse on the leaves of trees and to make constant efforts to reach them". As a matter of natural history, he probably wasn't right about how giraffes' necks came to be so long. But Lamarck was scorned for a much more general apparent mistake: the idea that lifestyle might be able to influence heredity. "Today," notes David Shenk, "any high school student knows that genes are passed on unchanged from parent to child, and to the next generation and the next. Lifestyle cannot alter heredity. Except now it turns out that it can . . ."
2 - Evolution is mostly horizontal
Even more devastating is the notion that genes do not just pass from parent to offspring, but between organisms.
What's more, evolution itself may have changed from horizontal to vertical. Vertical evolution merely a stage in an evoultion that evolves.
We've learned that huge proportions of the human genome consist of viruses, or virus-like materials, raising the notion that they got there through infection – meaning that natural selection acts not just on random mutations, but on new stuff that's introduced from elsewhere. Relatedly, there is growing evidence, at the level of microbes, of genes being transferred not just vertically, from ancestors to parents to offspring, but also horizontally, between organisms. The researchers Carl Woese and Nigel Goldenfield conclude that, on average, a bacterium may have obtained 10% of its genes from other organisms in its environment.
To an outsider, this is mind-blowing: since most of the history of life on earth has been the history of micro-organisms, the evidence for horizontal transfer suggests that a mainly Darwinian account of evolution may be only the latest version, applicable to the most recent, much more complex forms of life. Perhaps, before that, most evolution was based on horizontal exchange. Which gives rise to a compelling philosophical puzzle: if a genome is what defines an organism, yet those organisms can swap genes freely, what does it even mean to draw a clear line between one organism and another? "It's natural to wonder," Goldenfield told New Scientist recently, "if the very concept of an organism in isolation is still valid at this level." In natural selection, we all know, the fittest win out over their rivals. But what if you can't establish clear boundaries between rivals in the first place?
And what to make of recent developments in human-controlled genetic tinkering? Strides in scientific progress have enormous philosophical consequences for the thought of evolution as a random process.
3 - Ann Coulter is smarter than Darwin.
The American rightwing noisemaker Ann Coulter makes the point in her 2006 pro-creationist tirade Godless: The Church of American Liberalism. "Through the process of natural selection, the 'fittest' survive, [but] who are the 'fittest'? The ones who survive!" she sneers. "Why, look – it happens every time! The 'survival of the fittest' would be a joke if it weren't part of the belief system of a fanatical cult infesting the Scientific Community.":
Jerry Fodor, the American philosopher. Fodor's objection is a distant cousin of one that rears its head every few years: doesn't "survival of the fittest" just mean "survival of those that survive", since the only criterion of fitness is that a creature does, indeed, survive and reproduce.
As far as I can make out, it can be summarised in three steps. Step one: Fodor notes – undeniably correctly – that not every trait a creature possesses is necessarily adaptive. Some just come along for the ride: for example, genes that express as tameness in domesticated foxes and dogs also seem to express as floppy ears, for no evident reason. Other traits are, as logicians say, "coextensive": a polar bear, for example, has the trait of "whiteness" and also the trait of "being the same colour as its environment". (Yes, that's a brain-stretching, possibly insanity-inducing statement. Take a deep breath.) Step two: natural selection, according to its theorists, is a force that "selects for" certain traits. (Floppy ears appear to serve no purpose, so while they may have been "selected", as a matter of fact, they weren't "selected for". And polar bears, we'd surely all agree, were "selected for" being the same colour as their environment, not for being white per se: being white is no use as camouflage if snow is, say, orange.)
Step three is Fodor's coup de grace: how, he says, can that possibly be? The whole point of Darwinian evolution is that it has no mind, no intelligence. But to "select for" certain traits – as opposed to just "selecting" them by not having them die out – wouldn't natural selection have to have some kind of mind? It might be obvious to you that being the same colour as your environment is more important than being white, if you're a polar bear, but that's because you just ran a thought-experiment about a hypothetical situation involving orange snow. Evolution can't run thought experiments, because it can't think. "Darwin has a theory that centrally turns on the notion of 'selection-for'," says Fodor. "And yet he can't give an account – nobody could give an account – of how natural selection could distinguish between correlated traits. He waffles."
Link (http://www.guardian.co.uk/science/2010/mar/19/evolution-darwin-natural-selection-genes-wrong), with further links at the bottom.