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Birdsong Studies Lead To a Revolution In Biology
Smithsonian.com covers research that began with the study of birdsong and ended by overturning the common belief that adult animals can't produce new brain cells. "Deconstructing birdsong may seem an unlikely way to shake up biology. But [Fernando] Nottebohm's research has shattered the belief that a brain gets its quota of nerve cells shortly after birth and stands by helplessly as one by one they die — a 'fact' drummed into every schoolkid's skull. [Nottebohm] demonstrated two decades ago that the brain of a male songbird grows fresh nerve cells in the fall to replace those that die off in summer. The findings were shocking, and scientists voiced skepticism that the adult human brain had the same knack for regeneration. ... Yet, inspired by Nottebohm's work, researchers went on to find that other adult animals — including human beings — are indeed capable of producing new brain cells. And in February, scientists reported for the first time that brand-new nerves in adult mouse brains appeared to conduct impulses — a finding that addressed lingering concerns that newly formed adult neurons might not function."
Drink up, fellas!
I think I brain my damaged.
Be you Admins? nay, we are but lusers!
The whole "You only get so many cells" seemed counter intuitive to me. Logically it made very little sense. I never really cared though if it was true. I'm not a biologist nor did I ever do anything that would of required me to use such information. I always thought that You only get so many cell divisions seemed more likely. After all cells don't replicate perfectly.
This is actually very awesome as we have slowly made use of mice/rat brain cells as computing devices. This adds a whole new level, Just imagine a self-repairing/expanding computer... hmmmm maybe that's not such a good idea.
The new brain cells are still bird brain cells.
Fuck systemd. Fuck Redhat. Fuck Soylent, too. Wait, scratch the last one.
I learned that nerve, fat, and muscle cells didn't change in number during life*. Seems that's not true about neurons. Apparently also not true about fat cells ("If excess weight is gained as an adult, fat cells increase in size about fourfold before dividing and increasing the absolute number of fat cells present.") Anyone know the scoop on muscle cells?
* - Supposedly weight gain was due to the individual adipocytes getting larger, like a microcosmic obesity. And strength gain was due to more actin and myocin in each myocyte, like a micrcosmic bodybuilder.
I don't mean "duh" to the researcher -- obviously things must be tested and validated in the real world, not just postulated -- but it never made sense to me in the first place that brain cells can't regenerate. Why the hell not? What is the adaptive purpose of such a limitation? The brain consumes a huge amount of energy, much more so per-pound than any other organ in the body. That seems to imply that the brain is extremely important to the organism. Why would essentially the most important organ in the body have such a stupid limitation that it can't even recover from MINOR damage? That makes no sense.
One possible explanation for the very limited growth rate of brain cells is that if this growth rate were not tightly controlled, it could lead to "chaotic" brain tissue which could interfere with normal brain function. So general division of brain cells would not be desirable -- but I'm no neuroscientist.
In an episode of "Cheers," Cliff Clavin, the trivia-spouting, quirky, irksome mama's boy mailman is seated at the bar describing the buffalo theory to his buddy, Norm Peterson, the beer loving heavyweight bar stool sitting perpetual patron.
Cliff expounds his "Buffalo Theory" to Norm:
Well, you see, Norm, it's like this. A herd of buffalo can only move as fast as the slowest buffalo. And when the herd is hunted, it's the slowest and weakest ones at the back that are killed first. This natural selection is good for the herd as a whole, because the general speed and health of the whole group keeps improving by the regular killing of the weakest members.
In much the same way, the human brain can only operate as fast as the slowest brain cells. Now, as we know, excessive intake of alcohol kills brain cells. But naturally, it attacks the slowest and weakest brain cells first. In this way, regular consumption of beer eliminates the weaker brain cells, making the brain a faster and more efficient machine.
And that, Norm, is why you always feel smarter after a few beers.
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Don't get too excited yet. As the article states in humans the only well-established generation of new nerve cells occurs in the hippocampus, a structure which conveniently is involved in memory.
There was another study dating cells based on inclusion of radioisotopes left over from atmospheric nuclear weapons testing, apparently finding a very slow rate of new cell generation, measured in something like percent (or fraction thereof) per decade of the total. And their study only holds true if they correctly sorted their neurons from other cells that live in the brain (glia, blood vessels, etc). The study is actually pretty convincing, along with the Swedish BrdU study, but the rate of growth is less than stunning. The findings in birds of huge amounts of cortical growth are very cool and establish the principle that such massive growth can happen in an adult vertebrate.
What has not yet been established is what these new cells in humans might be doing, if anything. Even without new neurons, we can still be pretty flexible, by altering the strength of connections between neurons or forming entirely new connections.
Also even if the human brain does grow some new cells, the type of those cells is very important. for example, I heard a talk today from a guy with Parkinson's disease, which is a progressive disease of the cells of the substantia nigra, an area of the brain that is part of the system for controlling movement. He sure could use a few extra dopaminergic cells in his substantia nigra, but thats not happening for him, so the disease will kill him. So don't go on that brain cell massacre just yet.
Take a june bug, large and green...tie a string to it's leg and let him fly in circles. At the point where he starts to BLUR, that must be the speed of light. Figure the scale based on RPMs, etc the usual way.
SO: Speed of light: 34 mph!
Seriously: this standard stood for something like 700 years. Science: imperfect.
Wikipedia: Speed of light, history
Physics.virginua.edu: Speed of light
Worsleyschool: Measuring the speed of light
Early, scientific attempts to measure speed of light were very... Well... scientific. And quite accurate. In 1021 an Iraqi physicist realized that light has finite, variable speed that is slower in denser bodies.
In 1629-1667 there were several tries to measure how long it takes for light to move two miles. They all however got to the conclusion that it couldn't be measured because light's speed was so high and human reaction speed could not keep up
In late 1600s astronomers tried to find out the speed of light by observing the moons of Jupiter. They finally got pretty close to the actual value.
So a scientific view that is considered the "settled" "consensus" view can change in the face of contrary evidence? That's good to know.
That's exactly correct. That's precisely how science works, and it wouldn't work any other way. When you continue to believe something in the face of contrary evidence, that's called being (1) irrational, (2) stupid, or (3) both. Had you paid attention when the teachers were trying to explain this, you wouldn't be (1), (2) or (3).
But I will add that, as noted below, just because you're (1), (2) or (3), you're only wrong, not trolling. Someone who mods a comment down just because it's wrong is both (2), and (5) an asshole. A troll would be something like my using the missing (4), inserting into in the comment in the paragraph above following the first (1) (2) (3), to say something like "or (4) religious". While accurate, it is inappropriate, and therefore a troll. So don't do it. Not even if you're (5) like me and think it's funny.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
It's amazing how strong many scientists believe in certain things that are not even theories, and have a hard time changing their minds in the face of evidence to the contrary.
Why should we scientists be any different from the rest of you? We're people acting like people do, we just happen to be trying to figure things out in public. Besides, we have to believe something as a starting point so we can test an idea, and when we do have evidence, develop a theory which we can then further test to find out where we're wrong, discard that, and repeat the process. A science example of this is solar neutrinos. Despite many well designed experiments using well tested devices, only one third of the predicted amount was observed. None would be a failure, but a consistent one third? That would call for changing the theory. But they didn't. After decades someone came up with an idea of how the theory was right, but neutrinos themselves acted differently than expected. The same design was used to test the old solar neutrino theory plus the new neutrino behavior theory, and the found the solar neutrinos, oscillating between types. They didn't change their minds in the face of evidence and ended up correct.
It's also amazing how people, including us, refuse to believe something new (as opposed to just different from previous beliefs) even when well supported by evidence. A science example is the 80% positive replications of chemical transfer of learning. Even a colleague of James McConnell, the guy who started this field (and the Journal of Biological Psychology/Worm Runner's Digest), wrote in his obituary in science about this "failure", correct in his statement with respect to the field but wrong as a football bat about the theory. Scientists didn't change their minds (or come to believe something) in the face of evidence, and still haven't, and they're wrong.
Then there's conflicting theories. The two major theories of emotion are that we notice a physiological response, then attach a significance to it. The other is that we notice something, develop a cognitive response, and that causes a physiological response. Completely backwards from each other. Neither side would let go because they had plenty of evidence. After a while it came to be understood that both were right, it was emotions that occurred differently in different cases (phobias and PTSD, respectively).
And recall Einstein being interviewed when Eddington was going to measure light curvature around an eclipse to test relativity. When asked what would happen if the data were contrary to the theory, he said "then heaven help the data. The theory is correct." Eddington came back with some data and said he'd proved the theory correct and everybody believed it, and many still do. It was 70 years before a different test proved the theory correct. Subsequently, it was shown that the errors rate in the few measurements Eddington had were insufficient -- he was wrong, and so were everyone else that did and do believe his claim.
Three of these four examples are from "The Golem" by Collins and Pinch. That book very thoroughly and with references speaks to your observation but in all these different aspects, and more. It's simply the best source of examples of science being conducted as a human endeavor by plain old normal humans with human behaviors. It's instructive, illuminating and quite entertaining. And in the case of things that are correct but people continue to disbelieve, such as cold fusion, quite irritating. As a scientist that last bit, to quote Spock, "thrills me no end."
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
The history of science is full of consensus breaking ideas. Science is a discourse, not a religion. The only sacred truth is that there is no sacred truth. The consensus, however, can only be broken by _evidence_. So creation scientists and AGW deniers are out of luck.
Like all pain, suffering is a signal that something isn't right
Oh. And here I thought alcohol slowed down the whole herd, making the weak ones in the back (for once!) just as fast as the regular ones...
How did you get that many buffalo drunk?