Saturday 30 July 2016
David Berlinski on becoming David Berlinski.
How David Berlinski Came to Doubt Darwin
David Berlinski
ENV: When did you start thinking, as a critic, about Darwinian evolution? Did anythingIt was the fall of 1965. My graduate school roommate Daniel Messenger and I were ambling along Nassau Street in Princeton. We were munching the kind of wonderful Winesap apples that seem to have disappeared as a variety. I wonder why that is? Daniel's girlfriend, Sandra Petersen, was there too. Daniel was a fine philosopher and Sandra was doing a degree in classical philosophy. We walked over to Darwin's theory of evolution, living at the time in one of Princeton's back alleys.
A back alley was the right place to look for Darwin. No one in the philosophy department at Princeton had ever introduced his name into a seminar, or thought to argue that his theory was relevant to our concerns.
At Columbia College I had been given a ten minute introduction to the theory of evolution in a class otherwise devoted to comparative anatomy. The impression conveyed was that Darwin's theory was far less interesting than the details embedded in the anatomy of the Dogfish.
-- Now if you will turn to your specimens, Gentlemen...
If I had had those ten minutes to count on, Daniel had more. At Brown, he had once read Darwin's On the Origin of Species. This made him a considerable expert in my eyes. He knew what it was all about. I asked the obvious question: So is that it?
Apparently it was.
Daniel shrugged his rounded shoulders. Someone, he said, had figured it all out.
As she always did, Sandra kept her counsel. She was fond of Daniel; she thought me an idiot.
A year later, I found myself promoted from east coast snow to west coast sunshine. And promoted to more, far more. I was an assistant professor at Stanford: That was more. And I had been given access to the splendor of northern California: That was far more. What is that wonderful line by Robert Lowell? All of life's grandeur is something with a girl in summer.
One night I was having dinner with my great friend, Daniel Gallin. At the time, he lived in San Francisco, his Delmar Street apartment high above the city. We could see the fog roll in, Nassau Street Daniel emerging briefly to offer Delmar Street Daniel the same reprise of Darwin's theory that he had once offered me. Delmar Street Daniel was doing a PhD at Berkeley with Dana Scott; he was an excellent mathematician, and an even better logician. He reserved his approval for mathematical model theory, and his admiration for Alfred Tarski.
"Can you imagine?" he would ask on reading something absurd.
And Darwin?
Can you imagine!
*******************************************
At some time in the early 1970s, I came across the papers that Murray Eden and M.P. Schutzenberger had delivered to the 1966 Wistar Symposium, Mathematical Objections to Neo-Darwinism. I read them closely; I was impressed; and I discussed them at Columbia with Josh Kornberg, a molecular biologist, and George Pieczenik, a biochemist. Pieczenik had just finished his PhD, writing a thesis on the grammatical constraints embedded in the nucleic acids. Sympathetic to Murray's position, he had discovered two facts: The first, that the nucleic acids contain internal terminator codons and the second, that they often express very long palindromes. Josh Kornberg, on the other hand, had no intellectual capital to invest in either Murray or Marco. Not a dime, he said.
Who cares, he added?
For a while, I thought I might find a way to represent an evolutionary process in automata-theoretic terms. And for obvious reasons. The construction of a complex system demands some scheme of anticipation and deferral -- anticipation to determine where things are going, deferral to keep intermediates in reserve for later use. Finite state automata will not do; push-down storage automata are needed.
Sidney Morgenbesser accepted my paper for the Journal of Philosophy without asking for revisions. That my paper had very little to do with philosophy, he regarded as nothing more than an inconvenience. "Stick the word 'philosophy' in the title somewhere," he said. So I called my paper, "Philosophical Aspects of Molecular Biological Systems." Everyone was well satisfied, the philosophers because I was writing about biology, and the biologists because I was writing about philosophy.
It was my introduction to irrelevance, the writer's natural state.
Somewhat later, Noam Chomsky gave me a letter of introduction that allowed me to meet Marco Schutzenberger in Paris.
I've written about Chomsky and Marco in Black Mischief: Language, Life, Logic & Luck.
But this is the way it was. Darwin and I go back. He has long since moved from that scruffy back alley to something grand -- near Lake Cuomo, I believe. Still, it is lucky that we met. I might have encountered Marx instead of Darwin on Nassau Street, another one of the back-alley boys, the fall of the Berlin Wall leaving me, like Roger Kimball, dancing with ghosts. in your biography incline you to freethinking in that area?
David Berlinski
ENV: When did you start thinking, as a critic, about Darwinian evolution? Did anythingIt was the fall of 1965. My graduate school roommate Daniel Messenger and I were ambling along Nassau Street in Princeton. We were munching the kind of wonderful Winesap apples that seem to have disappeared as a variety. I wonder why that is? Daniel's girlfriend, Sandra Petersen, was there too. Daniel was a fine philosopher and Sandra was doing a degree in classical philosophy. We walked over to Darwin's theory of evolution, living at the time in one of Princeton's back alleys.
A back alley was the right place to look for Darwin. No one in the philosophy department at Princeton had ever introduced his name into a seminar, or thought to argue that his theory was relevant to our concerns.
At Columbia College I had been given a ten minute introduction to the theory of evolution in a class otherwise devoted to comparative anatomy. The impression conveyed was that Darwin's theory was far less interesting than the details embedded in the anatomy of the Dogfish.
-- Now if you will turn to your specimens, Gentlemen...
If I had had those ten minutes to count on, Daniel had more. At Brown, he had once read Darwin's On the Origin of Species. This made him a considerable expert in my eyes. He knew what it was all about. I asked the obvious question: So is that it?
Apparently it was.
Daniel shrugged his rounded shoulders. Someone, he said, had figured it all out.
As she always did, Sandra kept her counsel. She was fond of Daniel; she thought me an idiot.
A year later, I found myself promoted from east coast snow to west coast sunshine. And promoted to more, far more. I was an assistant professor at Stanford: That was more. And I had been given access to the splendor of northern California: That was far more. What is that wonderful line by Robert Lowell? All of life's grandeur is something with a girl in summer.
One night I was having dinner with my great friend, Daniel Gallin. At the time, he lived in San Francisco, his Delmar Street apartment high above the city. We could see the fog roll in, Nassau Street Daniel emerging briefly to offer Delmar Street Daniel the same reprise of Darwin's theory that he had once offered me. Delmar Street Daniel was doing a PhD at Berkeley with Dana Scott; he was an excellent mathematician, and an even better logician. He reserved his approval for mathematical model theory, and his admiration for Alfred Tarski.
"Can you imagine?" he would ask on reading something absurd.
And Darwin?
Can you imagine!
*******************************************
At some time in the early 1970s, I came across the papers that Murray Eden and M.P. Schutzenberger had delivered to the 1966 Wistar Symposium, Mathematical Objections to Neo-Darwinism. I read them closely; I was impressed; and I discussed them at Columbia with Josh Kornberg, a molecular biologist, and George Pieczenik, a biochemist. Pieczenik had just finished his PhD, writing a thesis on the grammatical constraints embedded in the nucleic acids. Sympathetic to Murray's position, he had discovered two facts: The first, that the nucleic acids contain internal terminator codons and the second, that they often express very long palindromes. Josh Kornberg, on the other hand, had no intellectual capital to invest in either Murray or Marco. Not a dime, he said.
Who cares, he added?
For a while, I thought I might find a way to represent an evolutionary process in automata-theoretic terms. And for obvious reasons. The construction of a complex system demands some scheme of anticipation and deferral -- anticipation to determine where things are going, deferral to keep intermediates in reserve for later use. Finite state automata will not do; push-down storage automata are needed.
Sidney Morgenbesser accepted my paper for the Journal of Philosophy without asking for revisions. That my paper had very little to do with philosophy, he regarded as nothing more than an inconvenience. "Stick the word 'philosophy' in the title somewhere," he said. So I called my paper, "Philosophical Aspects of Molecular Biological Systems." Everyone was well satisfied, the philosophers because I was writing about biology, and the biologists because I was writing about philosophy.
It was my introduction to irrelevance, the writer's natural state.
Somewhat later, Noam Chomsky gave me a letter of introduction that allowed me to meet Marco Schutzenberger in Paris.
I've written about Chomsky and Marco in Black Mischief: Language, Life, Logic & Luck.
But this is the way it was. Darwin and I go back. He has long since moved from that scruffy back alley to something grand -- near Lake Cuomo, I believe. Still, it is lucky that we met. I might have encountered Marx instead of Darwin on Nassau Street, another one of the back-alley boys, the fall of the Berlin Wall leaving me, like Roger Kimball, dancing with ghosts. in your biography incline you to freethinking in that area?
On human cloning:looks like the fun is just getting started.
Dolly Clones Pave the Way for Human Cloning
Wesley J. Smith
Apparently clones of the same dead sheep from which Dolly was manufactured are in good health and aging normally. From the Live Science story:
Four cloned sheep that are genetically identical to Dolly, the first cloned mammal, are still healthy even in old age, a new study found. The four sheep, which were derived from the same batch of cells as Dolly and could be considered her clone "sisters," have just reached their 9th birthday, which is equivalent to age 70 in human years, researchers who have been studying the sheep said.
A detailed study of these four sheep and nine other cloned sheep that are not related to "the Dollies" found that the animals were healthy. All of the sheep were free from many diseases commonly found in older sheep, such as diabetes and high blood pressure, the study showed.
What does this mean for the future of human cloning?
The technique, known as somatic cell nuclear transfer (SCNT) can be refined so as to permit normal mammals made in such a manner.
Human SCNT has already been done, creating embryos that were developed to the blastocyst stage (the time when stem cells can be derived).
SCNT is cloning. The result is an embryo. The question after that is how will that embryo be used.
Some human cloning apologists say that "therapeutic cloning" is different from "reproductive cloning." That's false. Those terms merely reflect different uses of the cloned embryo, the former being destroyed for research, the latter implanted in a uterus and -- as with Dolly -- brought to birth.
Bioethicists and Big Biotech support have said that human reproductive cloning should be banned until it is "safe."
Animal cloning moves that process forward as does therapeutic human cloning, since the point is to perfect the still faulty techniques needed to do in humans what is currently done in sheep.
The goals of human cloning include, but are not limited to research, learning how to genetically engineer, fetal farming, and reproductive outcomes.
Banning "reproductive cloning" is not banning cloning, but a use of a cloned embryo, in other words, a phony ban intended to fool people.
The time to outlaw human cloning is now -- meaning all human SCNT, regardless of the use to which the embryo will be put. If we wait until the sector perfects its techniques, it will be too late.
Will we? Not a chance. The media are asleep and/or active boosters of Big Biotech and Congress is safely in their campaign donation-paid special interest pockets.
There will be consequences.
Wesley J. Smith
Apparently clones of the same dead sheep from which Dolly was manufactured are in good health and aging normally. From the Live Science story:
Four cloned sheep that are genetically identical to Dolly, the first cloned mammal, are still healthy even in old age, a new study found. The four sheep, which were derived from the same batch of cells as Dolly and could be considered her clone "sisters," have just reached their 9th birthday, which is equivalent to age 70 in human years, researchers who have been studying the sheep said.
A detailed study of these four sheep and nine other cloned sheep that are not related to "the Dollies" found that the animals were healthy. All of the sheep were free from many diseases commonly found in older sheep, such as diabetes and high blood pressure, the study showed.
What does this mean for the future of human cloning?
The technique, known as somatic cell nuclear transfer (SCNT) can be refined so as to permit normal mammals made in such a manner.
Human SCNT has already been done, creating embryos that were developed to the blastocyst stage (the time when stem cells can be derived).
SCNT is cloning. The result is an embryo. The question after that is how will that embryo be used.
Some human cloning apologists say that "therapeutic cloning" is different from "reproductive cloning." That's false. Those terms merely reflect different uses of the cloned embryo, the former being destroyed for research, the latter implanted in a uterus and -- as with Dolly -- brought to birth.
Bioethicists and Big Biotech support have said that human reproductive cloning should be banned until it is "safe."
Animal cloning moves that process forward as does therapeutic human cloning, since the point is to perfect the still faulty techniques needed to do in humans what is currently done in sheep.
The goals of human cloning include, but are not limited to research, learning how to genetically engineer, fetal farming, and reproductive outcomes.
Banning "reproductive cloning" is not banning cloning, but a use of a cloned embryo, in other words, a phony ban intended to fool people.
The time to outlaw human cloning is now -- meaning all human SCNT, regardless of the use to which the embryo will be put. If we wait until the sector perfects its techniques, it will be too late.
Will we? Not a chance. The media are asleep and/or active boosters of Big Biotech and Congress is safely in their campaign donation-paid special interest pockets.
There will be consequences.
On S.E.T.I or still waiting by the phone.
After Fifty Years of Searching for ETs, Materialists Won't Take No for an Answer
Evolution News & Views
Ideas have consequences. If your idea is that life on Earth is nothing special, it follows that life should be plentiful in the cosmos. If you believe life and intelligence are accidental byproducts of matter and energy, you would probably want to communicate with others like us -- that is, unless (like Stephen Hawking) you think aliens might be as dangerous as we are to each other. Optimists in the SETI community outnumber pessimists. So they search.
And search. Half a century later, no signal has been detected. Astrobiologists (those who look for any kind of life beyond Earth, intelligent or not) can't even find microbes within our own solar system.
People are certainly free to pursue their own dreams. SETI only gets controversial when taxpayers have to pay for it. Search enthusiasts are chagrined that astrobiology gets NASA money, but they do not. Ever since Congress laughed it out of chambers with jokes about little green men, SETI advocates have had to raise their own money. With help from billionaires like Paul Allen and Yuri Milner, the search has continued. But even with technological innovations allowing the monitoring of a million channels simultaneously (far beyond Frank Drake's single-channel search of two stars in 1960), no signal of intelligent origin has yet turned up.
The true believers have one point in their favor; the search space is too vast to expect success in just 56 years, given our current search technology. But other possibilities exist. Life is rare; we are alone; or, perhaps, alien life is so different from what we know, we have no idea how to find it. From another direction, molecular biologists have continued to uncover unexpected complexity in even the simplest life, leading some to conclude life is rare.
These and other ideas are discussed in a paper by Nathalie A. Cabrol in the journal Astrobiology. A senior research scientist for the SETI Institute, Cabrol feels it's time for a major new interdisciplinary effort to look for intelligent aliens (see also Elizabeth Howell's write-up at Space.com, with video clip, "Are We Alone in the Universe?"). To succeed, Cabrol argues, we will need to expand our search to "life as we do not know it."
The evolutionary pathways that lead to complex life on Earth strongly suggest that advanced life as we know it may be rare in the Universe and unlikely to be in a state of advancement that is temporally synchronous with us. However, that does not mean that other types of advanced intelligences are as rare. Limiting our search to something we know and can de facto comprehend is, probabilistically, a constraining proposition, one that leaves no room for an epistemological and scientific foundation to explore alternate hypotheses. To find ET, we must expand our minds beyond a deeply rooted Earth-centric perspective and reevaluate concepts that are taken for granted. [Emphasis added; italics in the original.]
One way we can expand our minds is to play Mr. Spock and do a kind of "mind meld" with the aliens, using imagination. Here, Cabrol runs the risk of eliciting more Congressional guffaws:
Rather than constraining the search, SETI efforts must involve the most expansive exploration tool kit possible. If we unbind our minds, it should not matter whether ET looks or thinks like us, has a logic that makes any sense to us, or uses familiar technology for interstellar communication. ET is likely to be very different from us and completely alien to our evolutionary processes and thought processes, which may be deeply connected (see Section 5.2.3). Ultimately, to find aliens, we must become the aliens and understand the many ways they could manifest themselves in their environment and communicate their presence.
Such an intellectual framework not only moves the Drake equation forward toward the existence of drastically different probabilistic civilizations, it also brings us to consider alternate evolutionary pathways, including life as we do not know it and do not yet understand. Further, such a framework allows us to look at evolutionary pathways in our own biosphere and question the emergence of complex, intelligent life with a different set of eyes. For that to happen, we must conceptualize something we do not know, which can be approached in a number of different ways. One is by trying to access unknown concepts and archetypes that are literally alien to us (i.e., not part of our own evolutionary heritage) through imagination and discourse. This is what science fiction attempts to do in its depictions of alien worlds and civilizations. Not surprisingly, this process results in more or less elaborate versions of ourselves, since these representations are generated by neural systems wired to our own planetary environment. To conceptualize a different type of life, we have to step out of our brains. [Italics in the original.]
For those of us preferring to keep inside our brains, we see that ET can become an obsession to believers, like Richard Dreyfuss in Close Encounters, who would not take no for an answer. The silence does not mean aliens are not out there. They are just so alien we can't use the scientific method; we have to imagine them. We have to become them. Whether Cabrol's appeal will rouse support remains to be seen.
Cabrol is not alone. Fact-challenged as it is, SETI is a running theme in the popular science media. And there's a lot of money being thrown at it.
Ian O'Neill from Discovery News reports on a "targeted SETI" approach, using the Allen Telescope Array to listen for signals from candidate planets discovered by the Kepler Spacecraft. (Space.com)
China has just completed the world's largest radio telescope, in hopes of "finding new worlds and alien life." Though built for traditional science, "it can also eavesdrop on distant worlds to search for intelligent life," says Elias Brinks at The Conversation.
English scientists are practicing searches for exotic life deep in a salt mine, hoping to transfer what they learn to searches for life underground on Mars. (New Scientist)
New Scientist reports that several scientists are upset that NASA is not doing enough to search for alien life. They want more attention on the search in the Mars rover programs and the James Webb Space Telescope goals. Why? "As well as many other scientists who support the search for life elsewhere, it tops the lists of the most exciting questions driving science today for people outside the field," Shannon Hall writes.
At Live Science, Mindy Weisberger explores the fascination with "little green men" by examining the historical roots of the familiar icon that has persisted for decades.
Last month, a Cornell student, Evan Solomonides, presented "A Probabilistic Analysis of the Fermi Paradox," excusing the silence on the "Mediocrity Principle" wrongly attributed to Copernicus (see The Privileged Planet for refutation). Solomonides was inspired by Carl Sagan's view that humans are nothing special in the vastness of space. With that as his guide, he calculated (with no data on aliens) that it will be 1,500 years before aliens contact us. (Cornell Chronicle)
To appreciate how scientifically groundless these speculations are, imagine for a moment that a cult of religious fanatics controlled the reins of science. Convinced that ghosts are real, they search diligently for decades, creating more and more elaborate devices to find them. They refuse to take non-detection as an answer. Speculation joins imagination to explain why they are not found. Some of the true believers propose becoming ghosts to understand them. Others propose that ghosts are so clever, they are purposely concealing themselves. Another group speculates that they are so weird, we cannot even begin to imagine what they are like. Go ahead; use all the SETI speculations for this scenario. Even if these searches understood quantum physics and relativity and used sophisticated engineering, would that rationalize the ideology?
In the history of science, some searches for "occult phenomena" (referring not to spiritual entities, but to suspected-but-as-yet-unobserved realities) have borne fruit; recent examples include the Higgs Boson and gravitational waves. Other searches have not (caloric, phlogiston, alchemy). The search for dark matter is currently in crisis, failing the most sensitive search to date (Space.com). At some point, a quest must acquire data to justify its claim to be scientific.
Despite continued failures, SETI is unlikely to cave anytime soon. Its motivations are too deeply grounded in evolutionary ideology. The believers think it too incredible to imagine humans as unique or exceptional in such a vast universe. To be sure, this "gut feeling" extends outside evolutionary circles. But where is the evidence? While the complexity of life and the uniqueness of Earth have become more apparent, the aliens have remained silent.
Here are two points to note about this undying fascination with aliens in the SETI community and in the science media. One is its dependency on the materialist, Darwinian worldview. Cabrol's paper contains over a hundrew references to evolution in the text and references.
The second is the inherent inconsistency of this perspective. The SETI community is almost entirely composed of people who attack ID as unscientific. Yet over and over we see them using a framework of intelligent design, though not by that name, in their searches! SETI rests on the premise that intentional, purposeful signals can be distinguished from natural processes. They speak effusively about communication channels, signals, and intentions of beings that they don't even know exist. Remember this next time someone levels the charge against ID that it points to a designer outside of science.
Evolution News & Views
Ideas have consequences. If your idea is that life on Earth is nothing special, it follows that life should be plentiful in the cosmos. If you believe life and intelligence are accidental byproducts of matter and energy, you would probably want to communicate with others like us -- that is, unless (like Stephen Hawking) you think aliens might be as dangerous as we are to each other. Optimists in the SETI community outnumber pessimists. So they search.
And search. Half a century later, no signal has been detected. Astrobiologists (those who look for any kind of life beyond Earth, intelligent or not) can't even find microbes within our own solar system.
People are certainly free to pursue their own dreams. SETI only gets controversial when taxpayers have to pay for it. Search enthusiasts are chagrined that astrobiology gets NASA money, but they do not. Ever since Congress laughed it out of chambers with jokes about little green men, SETI advocates have had to raise their own money. With help from billionaires like Paul Allen and Yuri Milner, the search has continued. But even with technological innovations allowing the monitoring of a million channels simultaneously (far beyond Frank Drake's single-channel search of two stars in 1960), no signal of intelligent origin has yet turned up.
The true believers have one point in their favor; the search space is too vast to expect success in just 56 years, given our current search technology. But other possibilities exist. Life is rare; we are alone; or, perhaps, alien life is so different from what we know, we have no idea how to find it. From another direction, molecular biologists have continued to uncover unexpected complexity in even the simplest life, leading some to conclude life is rare.
These and other ideas are discussed in a paper by Nathalie A. Cabrol in the journal Astrobiology. A senior research scientist for the SETI Institute, Cabrol feels it's time for a major new interdisciplinary effort to look for intelligent aliens (see also Elizabeth Howell's write-up at Space.com, with video clip, "Are We Alone in the Universe?"). To succeed, Cabrol argues, we will need to expand our search to "life as we do not know it."
The evolutionary pathways that lead to complex life on Earth strongly suggest that advanced life as we know it may be rare in the Universe and unlikely to be in a state of advancement that is temporally synchronous with us. However, that does not mean that other types of advanced intelligences are as rare. Limiting our search to something we know and can de facto comprehend is, probabilistically, a constraining proposition, one that leaves no room for an epistemological and scientific foundation to explore alternate hypotheses. To find ET, we must expand our minds beyond a deeply rooted Earth-centric perspective and reevaluate concepts that are taken for granted. [Emphasis added; italics in the original.]
One way we can expand our minds is to play Mr. Spock and do a kind of "mind meld" with the aliens, using imagination. Here, Cabrol runs the risk of eliciting more Congressional guffaws:
Rather than constraining the search, SETI efforts must involve the most expansive exploration tool kit possible. If we unbind our minds, it should not matter whether ET looks or thinks like us, has a logic that makes any sense to us, or uses familiar technology for interstellar communication. ET is likely to be very different from us and completely alien to our evolutionary processes and thought processes, which may be deeply connected (see Section 5.2.3). Ultimately, to find aliens, we must become the aliens and understand the many ways they could manifest themselves in their environment and communicate their presence.
Such an intellectual framework not only moves the Drake equation forward toward the existence of drastically different probabilistic civilizations, it also brings us to consider alternate evolutionary pathways, including life as we do not know it and do not yet understand. Further, such a framework allows us to look at evolutionary pathways in our own biosphere and question the emergence of complex, intelligent life with a different set of eyes. For that to happen, we must conceptualize something we do not know, which can be approached in a number of different ways. One is by trying to access unknown concepts and archetypes that are literally alien to us (i.e., not part of our own evolutionary heritage) through imagination and discourse. This is what science fiction attempts to do in its depictions of alien worlds and civilizations. Not surprisingly, this process results in more or less elaborate versions of ourselves, since these representations are generated by neural systems wired to our own planetary environment. To conceptualize a different type of life, we have to step out of our brains. [Italics in the original.]
For those of us preferring to keep inside our brains, we see that ET can become an obsession to believers, like Richard Dreyfuss in Close Encounters, who would not take no for an answer. The silence does not mean aliens are not out there. They are just so alien we can't use the scientific method; we have to imagine them. We have to become them. Whether Cabrol's appeal will rouse support remains to be seen.
Cabrol is not alone. Fact-challenged as it is, SETI is a running theme in the popular science media. And there's a lot of money being thrown at it.
Ian O'Neill from Discovery News reports on a "targeted SETI" approach, using the Allen Telescope Array to listen for signals from candidate planets discovered by the Kepler Spacecraft. (Space.com)
China has just completed the world's largest radio telescope, in hopes of "finding new worlds and alien life." Though built for traditional science, "it can also eavesdrop on distant worlds to search for intelligent life," says Elias Brinks at The Conversation.
English scientists are practicing searches for exotic life deep in a salt mine, hoping to transfer what they learn to searches for life underground on Mars. (New Scientist)
New Scientist reports that several scientists are upset that NASA is not doing enough to search for alien life. They want more attention on the search in the Mars rover programs and the James Webb Space Telescope goals. Why? "As well as many other scientists who support the search for life elsewhere, it tops the lists of the most exciting questions driving science today for people outside the field," Shannon Hall writes.
At Live Science, Mindy Weisberger explores the fascination with "little green men" by examining the historical roots of the familiar icon that has persisted for decades.
Last month, a Cornell student, Evan Solomonides, presented "A Probabilistic Analysis of the Fermi Paradox," excusing the silence on the "Mediocrity Principle" wrongly attributed to Copernicus (see The Privileged Planet for refutation). Solomonides was inspired by Carl Sagan's view that humans are nothing special in the vastness of space. With that as his guide, he calculated (with no data on aliens) that it will be 1,500 years before aliens contact us. (Cornell Chronicle)
To appreciate how scientifically groundless these speculations are, imagine for a moment that a cult of religious fanatics controlled the reins of science. Convinced that ghosts are real, they search diligently for decades, creating more and more elaborate devices to find them. They refuse to take non-detection as an answer. Speculation joins imagination to explain why they are not found. Some of the true believers propose becoming ghosts to understand them. Others propose that ghosts are so clever, they are purposely concealing themselves. Another group speculates that they are so weird, we cannot even begin to imagine what they are like. Go ahead; use all the SETI speculations for this scenario. Even if these searches understood quantum physics and relativity and used sophisticated engineering, would that rationalize the ideology?
In the history of science, some searches for "occult phenomena" (referring not to spiritual entities, but to suspected-but-as-yet-unobserved realities) have borne fruit; recent examples include the Higgs Boson and gravitational waves. Other searches have not (caloric, phlogiston, alchemy). The search for dark matter is currently in crisis, failing the most sensitive search to date (Space.com). At some point, a quest must acquire data to justify its claim to be scientific.
Despite continued failures, SETI is unlikely to cave anytime soon. Its motivations are too deeply grounded in evolutionary ideology. The believers think it too incredible to imagine humans as unique or exceptional in such a vast universe. To be sure, this "gut feeling" extends outside evolutionary circles. But where is the evidence? While the complexity of life and the uniqueness of Earth have become more apparent, the aliens have remained silent.
Here are two points to note about this undying fascination with aliens in the SETI community and in the science media. One is its dependency on the materialist, Darwinian worldview. Cabrol's paper contains over a hundrew references to evolution in the text and references.
The second is the inherent inconsistency of this perspective. The SETI community is almost entirely composed of people who attack ID as unscientific. Yet over and over we see them using a framework of intelligent design, though not by that name, in their searches! SETI rests on the premise that intentional, purposeful signals can be distinguished from natural processes. They speak effusively about communication channels, signals, and intentions of beings that they don't even know exist. Remember this next time someone levels the charge against ID that it points to a designer outside of science.
Why appeals to common design re:homology are not a cop out.
Why Similarities Do Not Prove the Absence of Design
Granville Sewell
The idea that the "survival of the fittest" could produce all the magnificent species on Earth, and human brains and human consciousness, is so unreasonable -- how did such an idea ever become so widely accepted in the scientific world? There are two reasons.
First, science has been so successful explaining other phenomena in Nature that -- understandably -- today's scientist has come to expect that nothing can escape the explanatory power of his science. And Darwinism, as far-fetched as it is, is the best "scientific" theory he can come up with for evolution. As microbiologist René Dubos puts it in The Torch of Life, "[Darwinism's] real strength is that however implausible it may appear to its opponents, they do not have a more plausible one to offer in its place." But we have already seen why evolution is a very different and much more difficult problem than others solved by science, and why it requires a very different type of explanation.
Second, for most modern minds, the similarities between species not only prove common descent, they prove that evolution was the result of entirely natural causes, even in the absence of any evidence that natural selection can explain the major steps of evolution. The argument is basically, "This doesn't look like the way God would have created things," an argument used frequently by Darwin in the Origin of Species. But if the history of life does not give the appearance of creation by magic wand, it does look very much like the way we humans create things, through testing and improvements.
In fact, the fossil record does not even support the idea that new organs and new systems of organs arose gradually. Instead, new orders, classes, and phyla consistently appear suddenly. For example, Harvard paleontologist George Gaylord Simpson writes:
It is a feature of the known fossil record that most taxa appear abruptly. They are not, as a rule, led up to by a sequence of almost imperceptibly changing forerunners such as Darwin believed should be usual in evolution.... This phenomenon becomes more universal and more intense as the hierarchy of categories is ascended. Gaps among known species are sporadic and often small. Gaps among known orders, classes and phyla are systematic and almost always large. These peculiarities of the record pose one of the most important theoretical problems in the whole history of life: Is the sudden appearance of higher categories a phenomenon of evolution or of the record only, due to sampling bias and other inadequacies?
Actually, if we did see the gradual development of new orders, classes and phyla, that would be as difficult to explain using natural selection as their sudden appearance. How could natural selection guide the development of the new organs and entire new systems of interdependent organs which gave rise to new orders, classes, and phyla, through their initial useless stages, during which they provide no selective advantage? French biologist Jean Rostand, in A Biologist's View, wrote:
It does not seem strictly impossible that mutations should have introduced into the animal kingdom the differences which exist between one species and the next... [H]ence it is very tempting to lay also at their door the differences between classes, families and orders, and, in short, the whole of evolution. But it is obvious that such an extrapolation involves the gratuitous attribution to the mutations of the past of a magnitude and power of innovation much greater than is shown by those of today.
Rostand says, nevertheless, "However obscure the causes of evolution appear to me to be, I do not doubt for a moment that they are entirely natural."
We see this same pattern, of large gaps where major new features appear, in the history of human technology. (And in software development, as discussed in my Mathematical Intelligencer article "A Mathematician's View of Evolution.") For example, if some future paleontologist were to unearth two species of Volkswagens, he might find it plausible that one evolved gradually from the other. He might find the lack of gradual transitions between automobile families more problematic, for example, in the transition from mechanical to hydraulic brake systems, or from manual to automatic transmissions, or from steam engines to internal combustion engines. But if he thought about what gradual transitions would look like, he would understand why they didn't exist: There is no way to transition gradually from a steam engine to an internal combustion engine, for example, without the development of new, but not yet useful, features. He would be even more puzzled by the huge differences between the bicycle and motor vehicle phyla, or between the boat and airplane phyla. But heaven help us when he uncovers motorcycles and hovercraft, the discovery of these "missing links" would be hailed in all our newspapers as final proof that all forms of transportation arose gradually from a common ancestor, without design.
The similarities between the history of life and the history of technology go even deeper. Although the similarities between species in the same branch of the evolutionary "tree" may suggest common descent, similarities (even genetic similarities) also frequently arise independently in distant branches, where they cannot be explained by common descent. For example, in their Nature Encyclopedia of Life Sciences article on carnivorous plants, Wolf-Ekkehard Lönnig and Heinz-Albert Becker note that
...carnivory in plants must have arisen several times independently of each other... the pitchers might have arisen seven times separately, adhesive traps at least four times, snap traps two times and suction traps possibly also two times.... The independent origin of complex synorganized structures, which are often anatomically and physiologically very similar to each other, appears to be intrinsically unlikely to many authors so that they have tried to avoid the hypothesis of convergence as far as possible.
"Convergence" suggests common design rather than common descent: the probability of similar designs arising independently through random processes is very small, but a designer could, of course, take a good design and apply it several times in different places, to unrelated species. Convergence is a phenomenon often seen in the development of human technology. For example, Ford automobiles and Boeing jets may simultaneously evolve similar new GPS systems.
So if the history of life looks like the way humans, the only other known intelligent beings in the universe, design things -- through careful planning, testing, and improvements -- why is that an argument against design? Somehow we got the idea that nature's designer shouldn't need to get involved in the details, and so should be able to create anything from scratch, using a magic wand. But no matter how intelligent a designer is, he still has to get involved in the details -- that's what design is!
Some people counter by saying that of course cars cannot evolve like animals, because they cannot reproduce, so there are no "variations" for natural selection to work with. But the main point here is not about natural selection -- it is only that similarities between "species" (of cars or animals) do not prove the absence of design.
However, even though it is irrelevant to my main point here, let's look at the argument that evolution is easier to explain if there is reproduction. Is that really so? If cars were able to reproduce themselves almost perfectly (the copies even retaining the ability to reproduce themselves!), with occasional minor errors, would that make the evolution of cars easier to explain without design, than if individual cars experienced slight changes or improvements directly, though rust or crashes or other natural causes? We are so used to seeing animals make nearly perfect copies of themselves that we dismiss this as just another "natural" process; but if we saw cars giving birth to cars, maybe we would realize that this would actually make automobile evolution even more amazing and more difficult to explain without design.
Granville Sewell
The idea that the "survival of the fittest" could produce all the magnificent species on Earth, and human brains and human consciousness, is so unreasonable -- how did such an idea ever become so widely accepted in the scientific world? There are two reasons.
First, science has been so successful explaining other phenomena in Nature that -- understandably -- today's scientist has come to expect that nothing can escape the explanatory power of his science. And Darwinism, as far-fetched as it is, is the best "scientific" theory he can come up with for evolution. As microbiologist René Dubos puts it in The Torch of Life, "[Darwinism's] real strength is that however implausible it may appear to its opponents, they do not have a more plausible one to offer in its place." But we have already seen why evolution is a very different and much more difficult problem than others solved by science, and why it requires a very different type of explanation.
Second, for most modern minds, the similarities between species not only prove common descent, they prove that evolution was the result of entirely natural causes, even in the absence of any evidence that natural selection can explain the major steps of evolution. The argument is basically, "This doesn't look like the way God would have created things," an argument used frequently by Darwin in the Origin of Species. But if the history of life does not give the appearance of creation by magic wand, it does look very much like the way we humans create things, through testing and improvements.
In fact, the fossil record does not even support the idea that new organs and new systems of organs arose gradually. Instead, new orders, classes, and phyla consistently appear suddenly. For example, Harvard paleontologist George Gaylord Simpson writes:
It is a feature of the known fossil record that most taxa appear abruptly. They are not, as a rule, led up to by a sequence of almost imperceptibly changing forerunners such as Darwin believed should be usual in evolution.... This phenomenon becomes more universal and more intense as the hierarchy of categories is ascended. Gaps among known species are sporadic and often small. Gaps among known orders, classes and phyla are systematic and almost always large. These peculiarities of the record pose one of the most important theoretical problems in the whole history of life: Is the sudden appearance of higher categories a phenomenon of evolution or of the record only, due to sampling bias and other inadequacies?
Actually, if we did see the gradual development of new orders, classes and phyla, that would be as difficult to explain using natural selection as their sudden appearance. How could natural selection guide the development of the new organs and entire new systems of interdependent organs which gave rise to new orders, classes, and phyla, through their initial useless stages, during which they provide no selective advantage? French biologist Jean Rostand, in A Biologist's View, wrote:
It does not seem strictly impossible that mutations should have introduced into the animal kingdom the differences which exist between one species and the next... [H]ence it is very tempting to lay also at their door the differences between classes, families and orders, and, in short, the whole of evolution. But it is obvious that such an extrapolation involves the gratuitous attribution to the mutations of the past of a magnitude and power of innovation much greater than is shown by those of today.
Rostand says, nevertheless, "However obscure the causes of evolution appear to me to be, I do not doubt for a moment that they are entirely natural."
We see this same pattern, of large gaps where major new features appear, in the history of human technology. (And in software development, as discussed in my Mathematical Intelligencer article "A Mathematician's View of Evolution.") For example, if some future paleontologist were to unearth two species of Volkswagens, he might find it plausible that one evolved gradually from the other. He might find the lack of gradual transitions between automobile families more problematic, for example, in the transition from mechanical to hydraulic brake systems, or from manual to automatic transmissions, or from steam engines to internal combustion engines. But if he thought about what gradual transitions would look like, he would understand why they didn't exist: There is no way to transition gradually from a steam engine to an internal combustion engine, for example, without the development of new, but not yet useful, features. He would be even more puzzled by the huge differences between the bicycle and motor vehicle phyla, or between the boat and airplane phyla. But heaven help us when he uncovers motorcycles and hovercraft, the discovery of these "missing links" would be hailed in all our newspapers as final proof that all forms of transportation arose gradually from a common ancestor, without design.
The similarities between the history of life and the history of technology go even deeper. Although the similarities between species in the same branch of the evolutionary "tree" may suggest common descent, similarities (even genetic similarities) also frequently arise independently in distant branches, where they cannot be explained by common descent. For example, in their Nature Encyclopedia of Life Sciences article on carnivorous plants, Wolf-Ekkehard Lönnig and Heinz-Albert Becker note that
...carnivory in plants must have arisen several times independently of each other... the pitchers might have arisen seven times separately, adhesive traps at least four times, snap traps two times and suction traps possibly also two times.... The independent origin of complex synorganized structures, which are often anatomically and physiologically very similar to each other, appears to be intrinsically unlikely to many authors so that they have tried to avoid the hypothesis of convergence as far as possible.
"Convergence" suggests common design rather than common descent: the probability of similar designs arising independently through random processes is very small, but a designer could, of course, take a good design and apply it several times in different places, to unrelated species. Convergence is a phenomenon often seen in the development of human technology. For example, Ford automobiles and Boeing jets may simultaneously evolve similar new GPS systems.
So if the history of life looks like the way humans, the only other known intelligent beings in the universe, design things -- through careful planning, testing, and improvements -- why is that an argument against design? Somehow we got the idea that nature's designer shouldn't need to get involved in the details, and so should be able to create anything from scratch, using a magic wand. But no matter how intelligent a designer is, he still has to get involved in the details -- that's what design is!
Some people counter by saying that of course cars cannot evolve like animals, because they cannot reproduce, so there are no "variations" for natural selection to work with. But the main point here is not about natural selection -- it is only that similarities between "species" (of cars or animals) do not prove the absence of design.
However, even though it is irrelevant to my main point here, let's look at the argument that evolution is easier to explain if there is reproduction. Is that really so? If cars were able to reproduce themselves almost perfectly (the copies even retaining the ability to reproduce themselves!), with occasional minor errors, would that make the evolution of cars easier to explain without design, than if individual cars experienced slight changes or improvements directly, though rust or crashes or other natural causes? We are so used to seeing animals make nearly perfect copies of themselves that we dismiss this as just another "natural" process; but if we saw cars giving birth to cars, maybe we would realize that this would actually make automobile evolution even more amazing and more difficult to explain without design.
Darwinism Vs. the real world XXX
The Neuromuscular System: Your Body's Balancing Act
Howard Glicksman
Editor's note: Physicians have a special place among the thinkers who have elaborated the argument for intelligent design. Perhaps that's because, more than evolutionary biologists, they are familiar with the challenges of maintaining a functioning complex system, the human body. With that in mind, Evolution News is delighted to offer this series, "The Designed Body." For the complete series, see here. Dr. Glicksman practices palliative medicine for a hospice organization.
The nerves and muscles of our body allow us not only to breathe, but also to move around and manipulate things. But how do they do it? In my last I article showed that nerve cells (neurons) and muscle cells (myocytes) are excitable. This means that when adequately stimulated, they depolarize. By letting large amounts of Na+ ions enter, they cause the plasma membrane to go from being negatively charged to positively charged. Depolarization triggers large amounts of Ca++ ions to enter the cell, causing the neuron to release its neurotransmitter and the myocyte to contract.
The nervous system is set up like a military operation. Reconnaissance from sensory neurons within the peripheral nerves is sent to and organized by the spinal cord and transmitted to the brain. The brain, acting as headquarters, analyzes the sensory information, makes decisions, and sends out orders. The orders travel to and are organized by the spinal cord and sent through the motor neurons within the peripheral nerves. The messages tell the muscles to contract, which results in controlled and purposeful movement. The success of a military operation is dependent on having good information about the enemy and one's own troops. Let's look at some of the ways the body acquires the information it needs about its external and internal environment so it can know what to do and act accordingly.
Everyone knows that an odometer measures distance and a speedometer measures velocity. Each device is essentially a sensory transducer with a mechanism in place that enables it to sense a physical phenomenon and convert it into useful information. We have seen that the body has a whole host of sensory transducers, which provide the information necessary to maintain its internal environment. They are divided into three different categories: chemoreceptors, which respond to chemicals, like oxygen, glucose and calcium; mechanoreceptors, which respond to motion and stretch, like the baroreceptors in the walls of the arteries leading to the brain that monitor blood pressure; and physical sensors, which respond to natural phenomena, like the thermoreceptors in the hypothalamus that detect core temperature.
The skin not only protects the body from infection and injury. It also provides sensory information about its immediate surroundings. The skin has different sensory receptors that can detect light touch, pressure, motion, vibration, and temperature. It has pain receptors that react to chemicals related to nearby cell injury. They also react to too much pressure or motion and extreme temperatures. Adequate stimulation of any one of these sensory receptors causes the associated neuron to depolarize and release its neurotransmitter. The neurotransmitter then depolarizes a nearby connecting neuron in a cascade that transmits the message all the way to the brain, usually in the sensory region of the cerebral cortex.
In addition to the skin, which provides sensory information about the body's external environment, there are pain and mechanoreceptors in and around the joints, ligaments, and deep soft tissues. These, in addition to chemoreceptors within the major organs, provide sensory information about the body's internal environment. Although we are aware of many of the sensations caused by our external and internal environment, one set, the proprioceptors, acts unconsciously and without them life would be impossible.
Proprioception involves joint position awareness and kinesthesia, or the awareness of joint and limb movement through muscular effort. The proprioceptors tell the central nervous system about muscle length, joint position, and limb movement. If the body had no way of knowing what its muscles and joints were doing and where its bones were located in space, then how could it control its position and movements? In addition to the mechanoreceptors in and around the joints, the two main proprioceptors are the muscle spindles and the Golgi tendon organs, which provide sensory information on joint position and muscle movement.
The Golgi tendon organ joins the muscle to the tendon as it is attached on one end to the muscle fibers and on the other end to the tendon. Because it is directly connected, in series, to the muscle and the tendon, the Golgi tendon organ is sensitive to the degree of tension applied by muscle contraction.
An increase in tension causes the Golgi tendon organs to increase their impulses to the spinal cord, causing an immediate reflex inhibition of muscle contraction and a reduction in tension. This explains one of the important functions of the Golgi tendon organs: preventing muscle injury and tendon rupture by causing automatic muscle relaxation in the presence of dangerously high levels of tension.
Conversely, a decrease in tension causes the Golgi tendon organs to decrease their impulses to the spinal cord, which results in an immediate reflex reduction in inhibition causing an increase in muscle contraction. This explains another important function of the Golgi tendon organs, which is to help the body maintain its posture while performing goal directed activities.
Muscle fatigue, with its resulting diminished contraction, can lead to inadvertent falling or unexpected changes in position. But the information sent by the Golgi tendon organs to the spinal cord reflexively makes the flagging muscles contract more to allow the body to maintain its posture. Clearly, without the Golgi tendon organs to tell the central nervous system what's going on at the level of where the muscle attaches to the tendon, our ability to move around would be impossible.
Muscle spindles are sensory organs consisting of modified muscle fibers positioned in between and parallel to the skeletal muscle fibers, allowing them to compare their respective lengths. Since each skeletal muscle is usually attached to two different bones across a joint, its length also determines the angle of the joint and its position.
For example, when the elbow is fully extended to zero degrees, the biceps are at their greatest length and the triceps are at their shortest. In contrast, when the elbow is fully flexed at about 160 degrees, the biceps are at their shortest length and the triceps are at their greatest. When the angle of the elbow is in between, at 80 degrees, so too are the lengths of the biceps and the triceps. This demonstrates one of the functions of the muscle spindles, which is to provide the central nervous system with information about the length of each skeletal muscle and the angle and position of its associated joint.
If the skeletal muscle fibers are longer than the muscle spindles (an indication of being stretched) the muscle spindles react by sending more impulses to the spinal cord, reflexively causing muscle contraction. Conversely, if the skeletal muscle fibers are shorter than the muscle spindles (an indication of muscle contraction) the muscle spindles react by sending less impulses to the spinal cord which reflexively results in muscle relaxation. This demonstrates another important function of the muscle spindles. Like the Golgi tendon organs, they help the body maintain its posture and position in space while performing purposeful movements.
In a static situation, such as carrying a load in front of the body, it is easy to understand how the muscle spindles maintain position through changes in muscle function. In this setting, the elbows must be maintained at about ninety degrees by the combined actions of the biceps and triceps. During this activity, stretching (lengthening) of the biceps, due to muscle fatigue, will at the same time cause a shortening (contraction) of the triceps. If this is not corrected quickly the angle of the elbow will decrease and allow gravity to take more effect which may cause the load to be dropped.
To prevent this from happening, the muscle spindles in the biceps detect the lengthening and send more messages to the spinal cord, reflexively causing an increase in the contraction of the biceps. This maintains the angle of the elbow at ninety degrees so as to not drop the load. At the same time, the muscle spindles in the triceps detect the shortening of its muscle fibers and send out fewer messages to the spinal cord, reflexively resulting in relaxation of the triceps so that the ninety-degree elbow angle is maintained.
Clinical experience with diabetics and others who suffer from sensory nerve malfunction indicates that without any one of the above-mentioned sensory devices, it would have been impossible for our earliest ancestors to survive. Evolutionary biologists must explain how each of them came about and their presence in the precise locations where they are needed in addition to how intermediate life forms could have survived throughout this developmental process.
Next time we will look at the special sense of vision and see what it requires.
Howard Glicksman
Editor's note: Physicians have a special place among the thinkers who have elaborated the argument for intelligent design. Perhaps that's because, more than evolutionary biologists, they are familiar with the challenges of maintaining a functioning complex system, the human body. With that in mind, Evolution News is delighted to offer this series, "The Designed Body." For the complete series, see here. Dr. Glicksman practices palliative medicine for a hospice organization.
The nerves and muscles of our body allow us not only to breathe, but also to move around and manipulate things. But how do they do it? In my last I article showed that nerve cells (neurons) and muscle cells (myocytes) are excitable. This means that when adequately stimulated, they depolarize. By letting large amounts of Na+ ions enter, they cause the plasma membrane to go from being negatively charged to positively charged. Depolarization triggers large amounts of Ca++ ions to enter the cell, causing the neuron to release its neurotransmitter and the myocyte to contract.
The nervous system is set up like a military operation. Reconnaissance from sensory neurons within the peripheral nerves is sent to and organized by the spinal cord and transmitted to the brain. The brain, acting as headquarters, analyzes the sensory information, makes decisions, and sends out orders. The orders travel to and are organized by the spinal cord and sent through the motor neurons within the peripheral nerves. The messages tell the muscles to contract, which results in controlled and purposeful movement. The success of a military operation is dependent on having good information about the enemy and one's own troops. Let's look at some of the ways the body acquires the information it needs about its external and internal environment so it can know what to do and act accordingly.
Everyone knows that an odometer measures distance and a speedometer measures velocity. Each device is essentially a sensory transducer with a mechanism in place that enables it to sense a physical phenomenon and convert it into useful information. We have seen that the body has a whole host of sensory transducers, which provide the information necessary to maintain its internal environment. They are divided into three different categories: chemoreceptors, which respond to chemicals, like oxygen, glucose and calcium; mechanoreceptors, which respond to motion and stretch, like the baroreceptors in the walls of the arteries leading to the brain that monitor blood pressure; and physical sensors, which respond to natural phenomena, like the thermoreceptors in the hypothalamus that detect core temperature.
The skin not only protects the body from infection and injury. It also provides sensory information about its immediate surroundings. The skin has different sensory receptors that can detect light touch, pressure, motion, vibration, and temperature. It has pain receptors that react to chemicals related to nearby cell injury. They also react to too much pressure or motion and extreme temperatures. Adequate stimulation of any one of these sensory receptors causes the associated neuron to depolarize and release its neurotransmitter. The neurotransmitter then depolarizes a nearby connecting neuron in a cascade that transmits the message all the way to the brain, usually in the sensory region of the cerebral cortex.
In addition to the skin, which provides sensory information about the body's external environment, there are pain and mechanoreceptors in and around the joints, ligaments, and deep soft tissues. These, in addition to chemoreceptors within the major organs, provide sensory information about the body's internal environment. Although we are aware of many of the sensations caused by our external and internal environment, one set, the proprioceptors, acts unconsciously and without them life would be impossible.
Proprioception involves joint position awareness and kinesthesia, or the awareness of joint and limb movement through muscular effort. The proprioceptors tell the central nervous system about muscle length, joint position, and limb movement. If the body had no way of knowing what its muscles and joints were doing and where its bones were located in space, then how could it control its position and movements? In addition to the mechanoreceptors in and around the joints, the two main proprioceptors are the muscle spindles and the Golgi tendon organs, which provide sensory information on joint position and muscle movement.
The Golgi tendon organ joins the muscle to the tendon as it is attached on one end to the muscle fibers and on the other end to the tendon. Because it is directly connected, in series, to the muscle and the tendon, the Golgi tendon organ is sensitive to the degree of tension applied by muscle contraction.
An increase in tension causes the Golgi tendon organs to increase their impulses to the spinal cord, causing an immediate reflex inhibition of muscle contraction and a reduction in tension. This explains one of the important functions of the Golgi tendon organs: preventing muscle injury and tendon rupture by causing automatic muscle relaxation in the presence of dangerously high levels of tension.
Conversely, a decrease in tension causes the Golgi tendon organs to decrease their impulses to the spinal cord, which results in an immediate reflex reduction in inhibition causing an increase in muscle contraction. This explains another important function of the Golgi tendon organs, which is to help the body maintain its posture while performing goal directed activities.
Muscle fatigue, with its resulting diminished contraction, can lead to inadvertent falling or unexpected changes in position. But the information sent by the Golgi tendon organs to the spinal cord reflexively makes the flagging muscles contract more to allow the body to maintain its posture. Clearly, without the Golgi tendon organs to tell the central nervous system what's going on at the level of where the muscle attaches to the tendon, our ability to move around would be impossible.
Muscle spindles are sensory organs consisting of modified muscle fibers positioned in between and parallel to the skeletal muscle fibers, allowing them to compare their respective lengths. Since each skeletal muscle is usually attached to two different bones across a joint, its length also determines the angle of the joint and its position.
For example, when the elbow is fully extended to zero degrees, the biceps are at their greatest length and the triceps are at their shortest. In contrast, when the elbow is fully flexed at about 160 degrees, the biceps are at their shortest length and the triceps are at their greatest. When the angle of the elbow is in between, at 80 degrees, so too are the lengths of the biceps and the triceps. This demonstrates one of the functions of the muscle spindles, which is to provide the central nervous system with information about the length of each skeletal muscle and the angle and position of its associated joint.
If the skeletal muscle fibers are longer than the muscle spindles (an indication of being stretched) the muscle spindles react by sending more impulses to the spinal cord, reflexively causing muscle contraction. Conversely, if the skeletal muscle fibers are shorter than the muscle spindles (an indication of muscle contraction) the muscle spindles react by sending less impulses to the spinal cord which reflexively results in muscle relaxation. This demonstrates another important function of the muscle spindles. Like the Golgi tendon organs, they help the body maintain its posture and position in space while performing purposeful movements.
In a static situation, such as carrying a load in front of the body, it is easy to understand how the muscle spindles maintain position through changes in muscle function. In this setting, the elbows must be maintained at about ninety degrees by the combined actions of the biceps and triceps. During this activity, stretching (lengthening) of the biceps, due to muscle fatigue, will at the same time cause a shortening (contraction) of the triceps. If this is not corrected quickly the angle of the elbow will decrease and allow gravity to take more effect which may cause the load to be dropped.
To prevent this from happening, the muscle spindles in the biceps detect the lengthening and send more messages to the spinal cord, reflexively causing an increase in the contraction of the biceps. This maintains the angle of the elbow at ninety degrees so as to not drop the load. At the same time, the muscle spindles in the triceps detect the shortening of its muscle fibers and send out fewer messages to the spinal cord, reflexively resulting in relaxation of the triceps so that the ninety-degree elbow angle is maintained.
Clinical experience with diabetics and others who suffer from sensory nerve malfunction indicates that without any one of the above-mentioned sensory devices, it would have been impossible for our earliest ancestors to survive. Evolutionary biologists must explain how each of them came about and their presence in the precise locations where they are needed in addition to how intermediate life forms could have survived throughout this developmental process.
Next time we will look at the special sense of vision and see what it requires.
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