March 15th, 2006

homuncul

БИОЛОГИЯ

Про интеллект шимпанзе.....


Еще более сложной по своей структуре была задача (вернее, серия задач) на “тушение огня”, которую предлагалось решать Рафаэлю. Она состояла в том, чтобы достать апельсин из ящика, перед открытой стороной которого стояла горящая спиртовка. После многих и разнообразных проб он научился решать эту задачу разными способами:
- подтаскивал бак с водой к ящику и гасил огонь;
- набирал воды в рот и, возвратившись к огню, заливал его;
- набирал воды в кружку и гасил ею огонь;
- когда в баке не оказалось воды, Рафаэль схватил бутылку с водой и вылил ее на пламя. В другой раз, когда бак оказался пустым, он помочился в кружку и залил ею огонь.

Однако исследователи пытались снова и снова проанализировать, насколько осмысленны были действия обезьяны в этой ситуации.
Рафаэлю предлагали разные кружки и обнаружили, что он предпочитает пользоваться только той же самой кружкой, что и в период освоения этой операции. Стереотипность его поведения особенно ясно выступила, когда кружку продырявили и предложили ему пробки, палочки и шарики для затыкания отверстия. Оказалось, что Рафаэль не замечает отверстия, вновь и вновь подносит кружку под кран. Он не обратил внимания, что, случайно закрыв кружку ладонью, он временно приостановил вытекание воды, и не воспользовался этим приемом. Не обращая внимания на отсутствие воды, однажды он 43 раза опрокидывал над огнем пустую кружку, при этом не использовал ни одной из предложенных ему затычек, хотя ранее, во время игры делал это неоднократно.
Наконец, опыты перенесли на озеро, и ящик с приманкой поместили на один плот, а бак с водой - на другой, соединенный с первым довольно длинным и шатким мостиком. Рафаэль приложил массу усилий, чтобы принести воду из бака, вместо того чтобы зачерпнуть ее тут же, прямо с плота. Это окончательно убедило исследователей в его неспособности к пониманию истинных связей между элементами данной проблемной ситуации.
По их мнению, во всех проведенных опытах у шимпанзе отсутствовало “смысловое понимание задачи”, и все их поведение было основано прежде всего на ориентировочно-исследовательских пробах, а затем на закреплении связей от случайно достигнутого полезного результата. “Поведение человекообразной обезьяны определяется взаимодействием положительных и отрицательных условнорефлекторных связей... В решении новых задач обезьяна использует ранее выработанные навыки вне зависимости от смыслового содержания ситуации”


"Элементарное мышление животных", Учебное пособие. М.: Аспект Пресс, 2002.
http://ethology.ru/library/?id=66
homuncul

NEUROSCIENCE

Is Language the Key to Human Intelligence?
Science, Jan. 2004

What factors make humans unique? Spoken language? Recursion? In his Perspective, Premack uses a recent study showing that tamarin monkeys can acquire nonrecursive but not recursive grammar as a springboard to discuss various aspects of human uniqueness.
http://www.sciencemag.org/cgi/content/summary/sci;303/5656/318


Computational Constraints on Syntactic Processing in a Nonhuman Primate
Science, Jan. 2004

The capacity to generate a limitless range of meaningful expressions from a finite set of elements differentiates human language from other animal communication systems. Rule systems capable of generating an infinite set of outputs ("grammars") vary in generative power. The weakest possess only local organizational principles, with regularities limited to neighboring units. We used a familiarization/discrimination paradigm to demonstrate that monkeys can spontaneously master such grammars. However, human language entails more sophisticated grammars, incorporating hierarchical structure. Monkeys tested with the same methods, syllables, and sequence lengths were unable to master a grammar at this higher, "phrase structure grammar" level.
http://www.sciencemag.org/cgi/content/abstract/303/5656/377
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WILLIAM H. CALVIN, Ph.D., theoretical neurobiologist, Affiliate Professor of Psychiatry and Behavioral Sciences at the University of Washington in Seattle
http://williamcalvin.com/index.htm

"Lingua ex Machina: Reconciling Darwin and Chomsky with the Human Brain" (MIT Press, 2000)
http://williamcalvin.com/LEM/

"A Brief History of the Mind" (Oxford University Press 2004)
http://williamcalvin.com/BHM/index.htm
homuncul

NEUROSCIENCE

Knowledge of gravity hard-wired in the brain
New Scientist magazine, April 2005
http://www.newscientist.com/article.ns?id=mg18624965.300

Newton may have discovered the laws of gravity while relaxing under an apple tree, but his brain knew about them all along, according to an imaging study. It suggests that our brains have an internal model of gravity that helps us understand how objects move under its influence.
Francesco Lacquaniti at the Santa Lucia Foundation and the University of Rome, and his colleagues came up with this idea after observing how poor astronauts are at predicting the motion of objects in zero gravity. Now, using brain imaging, they have pinned down the brain region involved to the vestibular cortex, which handles information from the balance organs in the inner ear. It lit up when subjects saw objects moving normally under the influence of gravity, but was much less active when the movements were unnatural. So the region must be responding to gravity, not just movement.
The vestibular cortex seems to build up an internal model of gravity to help predict an object's motion. This is much more efficient than mentally running through thousands of possible types of motion, when most objects move in quite predictable ways, says Lacquaniti. And links to the balance organs may "calibrate" the gravity model.


Shadows are hardwired into the brain
http://www.newscientist.com/article.ns?id=dn4478
http://grani.ru/Society/Science/m.54246.html
Tags: ,
homuncul

БИОЛОГИЯ

Jellyfish see world through complex eyes
Nature, May 2005
http://www.abc.net.au/science/news/stories/s1366938.htm

Box jellyfish, which have no brain and only a basic nervous system, have surprisingly sophisticated eyes. And it appears Australian jellyfish may have the most sophisticated visual systems of all.

Researchers studied a small Caribbean species of jellyfish, Tripedalia cystophora, found in mangrove swamps in Puerto Rico. They report that the jellyfish boast impressive optical apparatus: a total of 24 eyes clustered at each of the creature's four corners.
homuncul

ПАНСПЕРМИЯ

A paper to appear in a scientific journal claims a strange red rain might have dumped microbes from space onto Earth four years ago.
http://www.world-science.net/exclusives/060104_specksfrm1.htm

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The scientists agree on two points, though. The things look like cells, at least superficially. And no one is sure what they are. “These particles have much similarity with biological cells though they are devoid of DNA”
The new paper includes a chemical analysis of the particles, a description of their appearance under microscopes and a survey of where they fell. It assesses various explanations for them and concludes that the specks, which vaguely resemble red blood cells, might have come from a meteor.
“I don’t have an obvious explanation,” agreed prominent origins-of-life researcher David Deamer of the University of California Santa Cruz. They “look like real cells, but with a very thick cell wall. But the leap to an extraterrestrial form of life delivered to Earth must surely be the least likely hypothesis.”
A range of additional tests is needed, he added. The researchers didn’t dispute the panspermia theory itself, which has a substantial scientific following. “Panspermia may well be possible,” wrote Lynn J. Rothschild of the NASA Ames Research Center in Moffett Field, Calif. “I’m just not so sure that this is a case of it.”



Astrophysics and Space Science, 2006
"The red rain phenomenon of Kerala and its possible extraterrestrial origin"
http://arxiv.org/abs/astro-ph/0601022


http://en.wikipedia.org/wiki/Red_rain_in_Kerala
homuncul

БИОЛОГИЯ

Цитоскелет сигнализирует
http://bio.1september.ru/2000/21/5.htm
http://bio.1september.ru/2000/22/5.htm


Journal of Cell Science (2003)
Tensegrity I. Cell structure and hierarchical systems biology
http://jcs.biologists.org/cgi/content/full/116/7/1157

Tensegrity II. How structural networks influence cellular information processing networks
http://jcs.biologists.org/cgi/content/full/116/8/1397


Ю.М. Васильев (член-корр. РАН) Клетка как архитектурное чудо
homuncul

БИОЛОГИЯ

GeneWatch magazine

"The DNA Era"
by Richard C. Lewontin
http://www.gene-watch.org/genewatch/articles/16-4lewontin.html

No one who reads the newspapers or scientific journals can have missed the fact that this is the 50th anniversary of the publication of the correct three-dimensional structure of DNA. That structure, a double helix of two chains of nucleotides, has become a popular icon and the very phrase, “double helix” has been spoken and written so often as to become part of ordinary discourse..

...The first step in building the claim for the dominance of DNA over all living processes has been the assignment of two special properties to DNA, properties that are asserted over and over again, not only in popular expositions but in textbooks. On the one hand, it is said that DNA is self-replicating; on the other, that DNA makes proteins, the molecular building blocks of cells. But both of these assertions are false - and what is sodisturbing is that every biologist knows they are false.


"Seeds of Doubt"
by Brandon Keim
http://www.gene-watch.org/genewatch/articles/16-4keim.html

"The Fall and Rise of Systems Biology"
by Stuart A. Newman
http://www.gene-watch.org/genewatch/articles/16-4newman.html
homuncul

ЭВОЛЮЦИЯ

Galapagos' 2005: World Summit on Evolution

Scientific American (June 2005)
http://www.sciam.com/print_version.cfm?articleID=00020722-64FD-12BC-A0E483414B7FFE87


In the discussion period University of Massachusetts theoretical biologist Lynn Margulis, in her inimitable rapid-fire style, hit Lazcano with a point-blank question: "In your opinion what came first, cells or the RNA world?" Lazcano answered: "If you define a cell as a membrane-enclosed system, then lipids-enclosed systems assisted in the polymerization of molecules, which led to RNA. Lipids and cells came first, then the RNA world."
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Bengtson: "We do not know because we have nothing else to go on. Life is an evolutionary bush, not an evolutionary tree, but our data based on extant life induce us to prune the bush into a tree, so we need more data."
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Interestingly, despite the impact of the five biggest mass extinctions (Ordovician 439 Ma, Devonian 367 Ma, Permian 245 Ma, Triassic 208 Ma, Cretaceous 65 Ma), many organism groups passed through all of these extinction episodes safely, such as the cockroach. "What is amazing is not only the extent of loss, but how fast life bounces back," Fortey concluded.
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Next on the roster was Peter Gogarten, a professor of molecular and cell biology at the University of Connecticut, who asked "Is the 'Tree of Life' a Tree?"
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U.C. Berkeley paleoanthropologist Timothy White:
If you want to get your fossil find published in Science or Nature, and you want the cover illustration, you cannot conclude that your fossil is yet another Australopithicus africanus, for example. You better come up with an interpretation indicating that this new find you are revealing for the first time to the world is the most spectacular discovery of the last century and that it promises to overturn hominid phylogeny and send everyone back to the drawing board to reconfigure the human evolutionary tree. Training a more skeptical eye on many of these fossils, however, shows that many, if not most of these fossils belong in already well-established categories. White says that the specimen labeled Kenyanthropus platyops, for example, is very fragmented and is most likely just another Australopithicus africanus. "Name diversity does not equal biological diversity," White elucidated.
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The final day of the conference began with a completely unorthodox lecture by Cornell University evolutionary theorist William Provine. The gist of his talk was that we need a new theory of evolution, after which he listed 11 problems that included this statement: "Natural selection does not shape an adaptation or cause a gene to spread over a population or really do anything at all. It is instead the result of specific causes: hereditary changes, developmental causes, ecological causes, and demography. Natural Selection is the result of these causes, not a cause that is by itself. It is not a mechanism."
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the penultimate lecture of the conference by the acknowledged star of the weekend, Lynn Margulis, famous for her pioneering research on symbiogenesis. Margulis began graciously by acknowledging the conference hosts and saying, "This is the most wonderful conference I've ever been to, and I've been to a lot of conferences." She then got to work, pronouncing the death of neo-Darwinism.
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The final talk was delivered by evolutionary biologist Joan Roughgarden, from Stanford University. Evolutionary skepticism must have been in the air, for on the heals of Margulis' pronouncement of the death of neo-Darwinism, Roughgarden proclaimed the death of Darwin's theory of sexual selection.
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The World Summit on Evolution, like most scientific conferences, revealed a science rich in history and tradition, data and theory, as well as controversy and debate. From this I conclude that the theory of evolution has never been stronger