Posted on 04/07/2006 4:16:49 AM PDT by PatrickHenry
Even as the evolution wars rage, on school boards and in courtrooms, biologists continue to accumulate empirical data supporting Darwinian theory. Two extraordinary discoveries announced this week should go a long way to providing even more of the evidence that critics of evolution say is lacking.
One study produced what biblical literalists have been demanding ever since Darwin -- the iconic "missing links." If species evolve, they ask, with one segueing into another, where are the transition fossils, those man-ape or reptile-mammal creatures that evolution posits?
In yesterday's issue of Nature, paleontologists unveiled an answer: well-preserved fossils of a previously unknown fish that was on its way to evolving into a four-limbed land-dweller. It had a jaw, fins and scales like a fish, but a skull, neck, ribs and pectoral fin like the earliest limbed animals, called tetrapods.
[big snip]
Another discovery addresses something Darwin himself recognized could doom his theory: the existence of a complex organ that couldn't have "formed by numerous, successive, slight modifications," he wrote in 1859.
The intelligent-design movement, which challenges teaching evolution, makes this the centerpiece of its attack. It insists that components of complex structures, such as the eye, are useless on their own and so couldn't have evolved independently, an idea called irreducible complexity.
(Excerpt) Read more at online.wsj.com ...
grey_whiskers comment: !!
Sorry, you asked for it:
A petunia is a flower just like a begonia
A begonia is a meat just like a sausage.
A-sausage and battery is a crime.
Monkeys crime trees.
Trees is a crowd.
The rooster crowd and made a lot of noise.
The noise is between the eyes.
Eyes are the opposite of nays.
A horse nays.
A horse also has a colt.
You may go to bed sometime with the window open and wake up with a colt if you're not careful!
Cheers!
Just got back from Mountain Biking up North, the first thing I did after putting perishables in the fridge was log into FR.
Nice post, but I probably won't have time to read up enough to comment intelligently upon it for 5 or 6 lifetimes :-)
Cheers!
Only thing better would be the northern lights blinking spiritual morse code begging to be decoded..
the emissions could be electromagnetic in the model I stipulated.
EM is well outside of my expertise, but iirc all EM exerts a small degree of thrust. On small particles, the effects of harmonics and cancellations should effect density.
additionally, the stipulated model describes a very dense and energetic aggregate. Even were it no denser than air at sea level, it would literally be LOUD. Particles would be bumping into each other, producing what can be treated as sound waves, and these waves would definitely form harmonics and cancellations, which in turn would definitely cause variance in the density of particulate distribution.
I look at entropy as tendency towards uniform distribution of energy in a closed system. Random distribution in an extremely large sample set if given sufficient time inevitably produces uniformity of distribution.
The tragedy is, you wrote a long and probably thoughtful post, based on the word of these shysters. If you want to learn about entropy, ask a physicist or physical chemist, not some 'panspermia guru', or a psychologist at something called the 'Center for the Ecological Study of Perception and Action' . Entropy isn't weird and it's not controversial. The stuff you're reading is new age garbage.
The Second Law is not restricted to closed systems. It says total entropy can never decrease. FWIW, 'closed system' is ambiguous. Some people define closed system as a system that does not interchange matter with the surroundings; some a system that interchanges neither mater nor energy. It's important to be careful about this.
Informational entropy is an analogy to thermodynamic entropy, nothing more. Shannon should have been shot for failing to come up with his own, distinct term. The second law does not apply, and therefore it's much less useful.
The recipe for a crystal is already present in the solution it grows from — the crystal lattice is prescribed by the structure of the molecules that compose it.
We know of some simple substances with as many as nine distinct crystal structures. Some recipe. And in fact, one of the most interesting issues in theoretical crystallography is why there are so few. This 'recipe' is something sophisticated condensed matter theorists can't yet reproduce.
He obscurantizes the trivial, and waves off the subtle.
Aye, sound waves are in that; but you seem to be suggesting that random motions would coalesce into ordered patterns.
Liesengang rings, you betcha, (not that I understand them); but I haven't "heard of" the same thing in sound; and the connection to E&M remains unclear to me.
Why don't you join bettyboop in one of those glasses of wine? I'll be along presently ... :-)
Cheers!
Cat's Cradle, wasn't it? Ice nine and all that?
I read once Vonnegut had a brother at GE Schenectady who suggested it, but I never did find out how they proposed to eliminate hydrogen bonding's influence.
Full Disclosure: Yah, I know ice ain't the same thing as phonons and lattice bands and yada yada. I just like puns and whimsey...
CheerS!
Oh! I'd definitely be up for that, dear friend!
I think water ice is up to 11 now, but that's pressure driven.There are compunds with 9 polymorphs at ambient pressure and temperature.
At very high pressure, you lose the hydrogen bonding network. Point is, crystallization is a thermodynamically non trivial problem, whereas the entropy of DNA is a staightforward calculation. The idea that evolution gives rise to some major decrease in entropy is simply incorrect.
(BTW, I read Cat's Cradle because Dickerson's Molecular Thermodynamics asked students to prove Ice Nine was impossible. I liked a book, so the proof was a bummer.)
Fully agreed.
The idea that evolution gives rise to some major decrease in entropy is simply incorrect.
Never said that. I once saw Murry Gell-Mann at a seminar when that subject came up from an audience member, and he rolled his eyes into the next county...
Cheers!
The whole point of ice-nine in the book is that the phase change to the high-melting structure happened at STP...,err, SP but actually somewhat warmer that std temp--otherwise one could not commit suicide by tasting it.
Cheers!
placemarker
I didn't intend to imply you did. It's just a frequently repeated error around here :-)
Did you realize that embryonic marsupials have an egg tooth, and that in fact for a while they're surrounded by an eggshell?
See the Source for details
No there isn't.
Yeah... and humans have a tail bone.. The human machine is a machine, as is all flesh.. The human spirit is another thing entirely.. i.e. a spirit riding the human machine as a rider.. not all machines are for transportation, but some are..
Is so.... and the skin that "makes" feathers is vastly different too.. skin that makes scales, skin that makes feathers, skin that makes hair.. are different from each other.. vastly different.. The survival of the creature depends on scales, feathers, or hair.. not the other way around.. Its almost like those things were "invented/designed" first and THEN the creature that uses them..
Perhaps you suffer from short attention span.
http://www.scienceblog.com/community/older/2002/B/20026658.html
October 2002
From University of Southern California
USC scientists uncover secrets of feather formation
'Jurassic Chicken' project may help studies of human development and evolution of dinosaurs
Los Angeles, Oct. 30, 2002 - Scientists from the Keck School of Medicine of the University of Southern California have, for the first time, shown experimentally the steps in the origin and development of feathers, using the techniques of molecular biology. Their findings will have implications for the study of the morphogenesis of various epithelial organs-from hairs to lung tissue to mammary glands-and is already shedding light on the controversy over the evolution of dinosaur scales into avian feathers.
A paper describing this work, "The Morphogenesis of Feathers", authored by principal investigator and Keck School pathology professor Cheng-Ming Chuong and his colleagues, was selected for advance online publication in the journal Nature and will be available as of October 30, 2002.
"The feather is one of the best research models you can find for understanding the basic molecular pathways used by all epithelial cells," says Chuong. "Scientists agree that whether you're looking at a human mammary gland or a chicken feather, epithelial cells use the same underlying logic, the same grammar, to form an organ. But unlike a gland, a feather really lays everything right out there for you."
The question of what makes a feather a feather has become rather heated in the recent past, with the discovery in China in the 1990s of fossilized dinosaurs like the Sinorthosaurus (Chinese-bird-dinosaur), with branching skin appendages on its skin. "Some say these things are feathers, some say they're protofeathers, others say they're not feathers at all," Chuong explains. "Everybody wants to know which one is the real first feather."
And they want to know how it came to be, as well. Over the years, Chuong notes, paleontologists trying to trace the evolutionary connection between dinosaurs and birds have looked at the ways in which a reptilian scale might turn into an avian feather.
Most adult feathers have a backbone, or stem, called a rachis, off of which the feather's barbs branch; each individual barb then branches again into the feather's smallest unit, the barbule, which is made of a single row of epithelial cells. Downy feathers, like those on a chick, lack a rachis altogether and are made up of just barbs studded with barbules. The standing hypothesis among many paleontologists has long been that the scales on dinosaurs must have lengthened into rachides that then became notched to form barbs and barbules. But there has been no real molecular evidence to either back up or refute that argument. Until now.
In their Nature paper, Chuong and his colleagues have demonstrated just how barbs and rachides are formed in a modern chicken, and have at the same time demonstrated that the evolution from scale to feather most likely followed a path in which the barbs form first and fuse to form a rachis-rather than a rachis forming first, and then being sculpted into barbs and barbules. This interaction between evolutionary biology and developmental biology (dubbed Evo-Devo) is a relatively new marriage of two previously disparate fields.
To come to their conclusions, Mingke Yu, the postdoctoral fellow and first author on the paper, along with colleagues Ping Wu and Randall B. Widelitz in Chuong's laboratory, developed a novel way to genetically manipulate different genes during feather formation. They plucked feathers from chickens, then prompted the chicken to regenerate those feathers under controlled conditions, raising and lowering the expression levels of the genes in question on an individual basis and observing the effects they had on the organization of epithelial cells into different feather forms.
Among others, three genes in particular-noggin, bone morphogenetic protein 4 (BMP4), and the whimsically named sonic hedgehog (Shh)-were found to result in new feathers that were rife with abnormal organization in their rachides and barbs. When Chuong's team increased the expression of noggin, for instance, they found that the rachis began to split into several small, thin rachides, and the barbs increased in number. When they increased the expression of BMP4, with which noggin interacts antagonistically, they found that the feather's rachis became gigantic and its barbs merged and were reduced in numbers. In this way, they were able to essentially manipulate the number and size of the feather's barbs and rachides.
Finally, when they suppressed Shh, they found a residual webby membrane between the normally separated barbs. "The cells there were supposed to go through apoptosis, or cell death," says Chuong, "in order to create the space between the barbs. But when we took away the sonic hedgehog signal, cell death no longer occurred. It is a similar process to that which occurs in the web of duck feet."
What can these new findings on the morphogenesis of feathers tell us about their evolution? "These results suggest that the barbs form first and later fuse to form a rachis, much like downy feathers are formed before flight feathers when a chicken grows up. Under the general rule of ontogeny repeating phylogeny, downy feather made only of barbs probably appeared before the evolution of feathers with rachides and capable of flight," Chuong says. "However, pinning down the exact moment at which dinosaur scales become chicken feathers is non-realistic. Just like Rome, feathers are not made in one process. It took 50 million years for Nature to refine the process, to transform a scale into a flight machine. There were many, many intermediate stages.
"While Darwin's theory has explained the 'why' of evolution, much of the 'how' remains to be learned," Chuong adds. "Evo-Devo research promises a new level of understanding."
These findings also have medical applications, notes Chuong. "With this study, we learned more about how nature guides epithelial stem cells to form different organs. For example, BMP, Shh and noggin are also used in different ways in making lungs, limbs and spinal cords. By analyzing these models, scientists may be able to fully understand nature's 'grammar,' and learn to use it in repairing or regenerating tissues and organs, which we call tissue engineering."
This research was supported by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health, and from the National Science Foundation.
Mingke Yu, Ping Wu, Randall B. Widelitz and Cheng-Ming Chuong, _The Morphogenesis of Feathers._ Nature advance online publication, 30 October 2002 (doi:10.1038/nature01196).
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