Evolutie. Deel XIV

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Gene mutation linked to cognition is found only in humans

The human and chimpanzee genomes vary by just 1.2 percent, yet there is a considerable difference in the mental and linguistic capabilities between the two species. A new study showed that a certain form of neuropsin, a protein that plays a role in learning and memory, is expressed only in the central nervous systems of humans and that it originated less than 5 million years ago. The study, which also demonstrated the molecular mechanism that creates this novel protein, will be published online in Human Mutation, the official journal of the Human Genome Variation Society.

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Research confirms theory that all modern humans descended from the same small group of people

he genetic survey, produced by a collaborative team led by scholars at Cambridge and Anglia Ruskin Universities, shows that Australia's aboriginal population sprang from the same tiny group of colonists, along with their New Guinean neighbours.

The research confirms the “Out Of Africa” hypothesis that all modern humans stem from a single group of Homo sapiens who emigrated from Africa 2,000 generations ago and spread throughout Eurasia over thousands of years. These settlers replaced other early humans (such as Neanderthals), rather than interbreeding with them.

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Until now, one of the main reasons for doubting the “Out Of Africa” theory was the existence of inconsistent evidence in Australia. The skeletal and tool remains that have been found there are strikingly different from those elsewhere on the “coastal expressway” – the route through South Asia taken by the early settlers.

Some scholars argue that these discrepancies exist either because the early colonists interbred with the local Homo erectus population, or because there was a subsequent, secondary migration from Africa. Both explanations would undermine the theory of a single, common origin for modern-day humans.

But in the latest research there was no evidence of a genetic inheritance from Homo erectus, indicating that the settlers did not mix and that these people therefore share the same direct ancestry as the other Eurasian peoples.

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Op donderdag 10 mei 2007 10:16 schreef Monolith het volgende:

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http://www.physorg.com/news97857326.html

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Op maandag 14 mei 2007 10:10 schreef SpecialK het volgende:

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Ik denk dat je dan een stukje moet vertalen van talkorigines. Ik ken eigenlijk maar weinig nederlandse sites met een "bewijs" - "tegenbewijs" format over dit onderwerp.

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Human ancestor not so brainy
By Will Dunham

A monkey-like animal seen as an ancestor of monkeys, apes and humans was not as brainy as expected, according to scientists who analyzed its nicely preserved 29-million-year-old skull.

The finding indicated that primate brain enlargement evolved later than once thought, the researchers said on Monday.

They analyzed a remarkably well-preserved fossilized skull of the little primate Aegyptopithecus zeuxis, which lived in the trees and ate fruit and leaves about 29 million years ago in warm forests in what is now an Egyptian desert.

A technique called microcomputerized tomography scanning -- a computerized X-ray method also called micro-CT -- allowed them to determine the dimensions of the animal's brain.

"What was astonishing is how small this brain is," Duke University primatologist Elwyn Simons, who led the study in the Proceedings of the National Academy of Sciences, said in a telephone interview.

"You can also see it's a pretty darn primitive brain. It would be small for a monkey or an ape," Simons added. "So it's telling us that the speed of achievement of brain enlargement in primates was a little slower than perhaps we had thought."

This skull of a small female was uncovered in a quarry southwest of Cairo in 2004. It was better preserved than another skull of a larger male of the species found in the same area in 1966.

Based on earlier finds, scientists had theorized the species had a relatively large brain. Instead, it had a brain that might have been even smaller than that of a modern lemur, a primate with primitive traits.

The condition of the earlier skull -- "smashed up," as Simons put it -- prevented the analysis possible with the newer one.

"YOU NEED TO BE SMARTER"

Simons said that when this primate lived, Africa was an island, limiting the competition for survival. Simons said brain enlargement may have evolved in this lineage after Africa became connected to Asia, bringing in more animals including new and dangerous predators.

"Brain-volume enlargement is favored under conditions of competition because you need to be smarter," Simons said.

Aegyptopithecus is sometimes called "Dawn Ape." Simons said it looked somewhat like an ape, particularly in its teeth and skull, and said it is thought to be close to the ancestry of monkeys, apes and humans.

"Because of the proportions of having a fairly robust chewing mechanism and a small brain, its skull looks like an ape's skull. It looks like a miniaturized gorilla," Simons said.

The new skull fits easily into a person's palm and is less than half the size of the 1966 skull. The researchers think it was from a female weighing perhaps 5.5 pounds (2.5 kg), while the earlier one was from a male more than twice as big.

They said this size difference between the sexes of this species is similar to that of gorillas.

Simons said that he previously overestimated its brain size based on features of the 1966 skull, which has a bigger snout and more pronounced crests. Those features now seem to be attributes of a male of the species.

Other aspects of its remains indicate it was branching off from its lemur-like ancestors.

For example, its skull indicates the brain's visual cortex was large, suggesting it had very good vision -- an important characteristic of higher primates. Its eye sockets also indicate it was active during the day. Many more primitive primates are nocturnal.

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Op dinsdag 15 mei 2007 00:43 schreef SpecialK het volgende:
Grappig dat er in dit stukje een referentie wordt gemaakt naar de tanden van de schedel als zijnde "more apelike". Ik vraag me af of de verzwakking van onze kaken (want we hebben geen bijtkracht vergeleken met andere primaten) dus iets is wat tegelijkertijd met de grootte van de schedel is veranderd.
Zou de structuur van een grotere schedel in de weg zitten van de kaak ivbm het bot of de aanhechtingspunten of dikte van de spieren?

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In Biology, epigenetics is the study of all heritable and potentially reversible changes in genome function that do not alter the nucleotide sequence within the DNA. When a cell undergoes an epigenetic change, it is the phenotype of the cell that is affected. Epigenetic events during embryo development lead to the differentiation of fetal cells. The combined processes of fetal development and cell differentiation are called epigenesis. The term is also sometimes used as a synonym for the closely related topic of chromatin remodeling.

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The philosophical implications of epigenetics have been discussed by scientists such as Eva Jablonka, Marion Lamb and Massimo Pigliucci, who cite epigenetic inheritance as one of a number of factors suggesting that the neo-darwinian synthesis of the early twentieth century is incomplete. Jablonka and Lamb suggest that the standard way of thinking about evolution, in terms of changes in the frequency of one or more isolated genes needs to be questioned, and that, contrary to long-held majority opinion, not all genetic variation is entirely random or blind - some may be regulated and partially directed and that the concept of heridity that is currently being used in evolutionary thinking is far too narrow. Pigliucci suggests, in Nature that If one accepts this bold, expanded version of heredity and evolution, it turns out that evolution can proceed very rapidly and phenotypic modification can precede genetic changes, and that changes at the genetic level will often simply stabilize adaptive modifications that are initiated through phenotypic plasticity, epigenetic control mechanisms, or behavioural and symbolic means; that this framework would greatly help to solve old problems in evolutionary biology, such as the origin of novel structures, and that the ultra-reductionist, gene-centred approach has (at least partially) failed.

The extent to which evolution operates at several different levels is the nub of Patrick Bateson's "friendly disagreement" with Richard Dawkins. In a critique of determinism Robert Winston suggests that epigenetic inheritance is an important factor in the inadequacy of the "selfish gene" and "DNA" metaphors.

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Op donderdag 24 mei 2007 08:31 schreef osho het volgende:
Chinese kat heeft vleugels

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Op donderdag 24 mei 2007 08:34 schreef Invictus_ het volgende:

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Erm, nee. Neem die maar mee naar TRU.

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Op donderdag 24 mei 2007 08:31 schreef osho het volgende:
Chinese kat heeft vleugels

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Op donderdag 24 mei 2007 08:31 schreef osho het volgende:
Chinese kat heeft vleugels

[afbeelding]

de vraag is natuurlijk in hoeverre dit geen photoshop is maar anders is het best een leuke mutatie

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Op donderdag 24 mei 2007 17:59 schreef barthol het volgende:

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Ik ga even muggenziften, maar wel met een doel. Ik zie namelijk te vaak misverstanden in evolutiediscussies onstaan door een verkeerd beeld van wat er met mutaties bedoeld wordt.
Te vaak is het beeld dat een mutatie een fenotypische verandering is. Een lichamelijke bijzonderheid.
Eigenlijk net zo als die opmerking "maar anders is het best een leuke mutatie"

Het gesimplificeerde beeld van evolutie van evolutie wordt dan vervolgens een wereld waarin die "mutanten" via natuurlijke selectie met elkaar concureren via het principe van de "survival of the fittest". Maar bij evolutie wordt het accent door evolutionair biologen tegenwoordig veel meer op de genetica gelegd. Het bovenstaande beeld is verouderd en verre van compleet om de evolutie goed te begrijpen. Bij het begrip "mutatie" probeer ik wat puristisch te zijn en "Mutatie" en "het gevolg van een mutatie" strikt te scheiden. Een mutatie is puur een verandering in het DNA, Als een dier vreemde of nieuwe kenmerken gaat vertonen is het dier geen mutatie. Ook de lichamelijke kenmerken zijn niet een mutatie. Het kan wel "het gevolg" van een mutatie zijn. Een mutatie is slechts een verandering in het Dna, en dat met of zonder gevolgen voor hoe het dier eruitziet of functioneert.

Ik ben wat puristisch, maar ik merk vaak dat er in evolutiediscussies een miscommunicatie onstaat door verkeerde voorstellingen van wat er met mutaties bedoeld wordt. De opmerking in de quote vond ik een mooie gelegenheid om het nog een keer zo te verwoorden.

groet.

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This week, the creationist Ken Ham and his organization, Answers in Genesis, are practicing the Big Lie.

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Op zondag 27 mei 2007 22:40 schreef Ali_Kannibali het volgende:
Lekkere opening weer:
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whaha

* heel die text is echt ontzettend haatdragend zeg

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Remains of giant dinosaur found in China

By AUDRA ANG, Associated Press Writer



BEIJING - The remains of a giant, birdlike dinosaur as tall as the formidable tyrannosaur have been found in China, a surprising discovery that indicates a more complicated evolutionary process for birds than originally thought, scientists said Wednesday.

Fossilized bones uncovered in the Erlian Basin of northern China's Inner Mongolia region show that the specimen was about 26 feet long, 16 feet tall and weighed 3,000 pounds, said Xu Xing, a paleontologist at the Institute of Vertebrate Paleontology & Paleoanthropology in Beijing.

The height is comparable to the meat-eating tyrannosaurs. But the dinosaur, called Gigantoraptor elrianensis, also had a beak and slender legs and likely had feathers. It was 35 times larger than its likely close relation, the Caudiperyx, a small, feathered dinosaur species, Xu said.

That puts the Gigantoraptor's existence at odds with prevailing theories that dinosaurs became smaller as they evolved into birds and that bigger dinosaurs had less birdlike characteristics, he said.

"This is like having a mouse that is the size of a horse or cow," said Xu, who co-authored a paper on the finding published Thursday in the journal Nature. "It is very important information for us in our efforts to trace the evolution process of dinosaurs to birds. It's more complicated than we imagined."

The Caudiperyx and the Gigantoraptor belong to a group of dinosaurs called oviraptors, which tend to be human-sized or smaller. In recent years paleontologists have found turkey-sized, feathered representatives of the group, but they have never found anything close to the scale of Gigantoraptor.

"It's one of the last groups of dinosaurs that we would expect to be that big," said Mark Norell, curator of paleontology at the American Museum of Natural History in New York City.

But Philip Currie, a paleontologist at the University of Alberta, said the size of the Gigantoraptor would be a natural step in the evolutionary process of the oviraptors.

"Almost every group that has evolved has tended to evolve giant forms," Currie said.

Animals tend to become bigger with evolution because larger creatures have an easier time getting food, impressing potential mates and avoiding predators.

But size has disadvantages, too. Bigger animals need more food and territory. They have fewer offspring and reproduce less frequently than smaller animals do. That means they are particularly vulnerable when environmental conditions change, as they abruptly did about 65 million years ago. Just a few million years after Gigantoraptor evolved, it and every other dinosaur species on Earth became extinct.

On Wednesday, reporters were given a look at the Gigantoraptor's remains — two yellowing, rough-edged leg bones both a little over 3.2 feet long and believed to be those of a young adult.

It has not been determined whether the Gigantoraptor was a herbivore, which have small heads and long necks, or a carnivore, which have sharp claws. The dinosaur has both, Xu said.

Xu and his team, which discovered three other specimens in the fossil-rich Erlian Basin, were being interviewed by Japanese media in 2005 when they discovered the Gigantoraptor remains.

They had chosen a random site to illustrate how one of the previous fossils had been discovered and hit upon a bone while on camera, Xu said. The team originally thought that it belonged to a tyrannosaur because of its size, but realized upon examination that it was an oviraptor.

"It was an unexpected finding," Xu said.

___

Associated Press writer Matt Crenson in New York contributed to this story.

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Op donderdag 14 juni 2007 01:58 schreef barthol het volgende:
Even nog een artist impression van die Gigantoraptor,
Zo groot als een T-rexx maar meer bird-like
Echt een vreemde vogel.

[afbeelding]

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An international research consortium today published a set of papers that promise to reshape our understanding of how the human genome functions. The findings challenge the traditional view of our genetic blueprint as a tidy collection of independent genes, pointing instead to a complex network in which genes, along with regulatory elements and other types of DNA sequences that do not code for proteins, interact in overlapping ways not yet fully understood.

In a group paper published in the June 14 issue of Nature and in 28 companion papers published in the June issue of Genome Research, the ENCyclopedia Of DNA Elements (ENCODE) consortium, which is organized by the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health (NIH), reported results of its exhaustive, four-year effort to build a parts list of all biologically functional elements in 1 percent of the human genome. Carried out by 35 groups from 80 organizations around the world, the research served as a pilot to test the feasibility of a full-scale initiative to produce a comprehensive catalog of all components of the human genome crucial for biological function.

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Op zondag 27 mei 2007 22:36 schreef Invictus_ het volgende:
[afbeelding]

Hét museum is open en de blogosphere trakteert ons op commentaar onder redactie van PZ.

http://scienceblogs.com/p(...)_creation_museum.php

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In May of 2005, a 3-member subcommittee of the Kansas State Board of Education held hearings to determine whether Darwin's long-held Theory of Evolution should be challenged in public-school science curriculum. At stake was, in effect, the definition of science for Kansas schoolchildren.

Kansas vs. Darwin takes you inside the hearings to meet the characters who captured the world's attention: school board members who believe their literal interpretation of the Bible trumps modern scientific evidence, and members of the Intelligent Design Network who believe mainstream science is conspiring to suppress evidence that would overturn evolution. You'll also get face to face with an organization of Kansas scientists, educators, and citizens that organizes a worldwide response to put an end to what they see as a religiously-motivated kangaroo court.

Kansas vs. Darwin is a heady, absorbing swirl of politics, science, religion, education and emotion in which the filmmakers unflinchingly race from one, compelling point of view to its polar opposite in order to challenge the viewer's own opinions. Audiences may experience discomfort as they plunge to the heart of one of mankind's most central questions of existence - and to the epicenter of the American culture war.

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In the corner of a laboratory at Michigan State University, one of the longest-running experiments in evolution is quietly unfolding. A dozen flasks of sugary broth swirl on a gently rocking table. Each is home to hundreds of millions of Escherichia coli, the common gut microbe. These 12 lines of bacteria have been reproducing since 1989, when the biologist Richard E. Lenski bred them from a single E. coli. “I originally thought it might go a couple thousand generations, but it’s kept going and stayed interesting,” Dr. Lenski said. He is up to 40,000 generations now, and counting.

*snip*

“It’s fun for us, because we can watch the game of life at the molecular level,” said Bernhard Palsson of the University of California, San Diego. “Many features of evolutionary theory are showing up in these experiments, and that’s why people are so excited by them.”

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Op woensdag 27 juni 2007 00:11 schreef wijsneus het volgende:
An irreducibly complex system has evolved in bacteria within the past 70 years.

http://www.talkdesign.org/faqs/icdmyst/ICDmyst.html#how2eatpcp

--
http://www.biology.mcgill(...)Harrison/schmidt.pdf

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Op woensdag 27 juni 2007 08:56 schreef Rumboon het volgende:

De huidige westerse mens heeft echter niet meer te maken met deze natuurlijke selectie. Dankzij medische ingrepen kunnen zelfs geestelijk gehandicapten langer leven en zich voortplanten. Hierdoor kan ik toch aannemen dat wij niet meer evolueren? Hoe moet ik dit zien...?

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Op woensdag 27 juni 2007 07:55 schreef bigore het volgende:

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Auw, als dit waar is en op de juiste manieren getoetst is/word kan dit een gigantische klap in de bek voor creationisten worden. Hopelijk horen we hier meer over.

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Op woensdag 27 juni 2007 00:11 schreef wijsneus het volgende:
An irreducibly complex system has evolved in bacteria within the past 70 years.

http://www.talkdesign.org/faqs/icdmyst/ICDmyst.html#how2eatpcp

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Op woensdag 27 juni 2007 09:47 schreef Dwerfion het volgende:

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Noemt de ID-beweging iets wat uit 3 enzymen bestaat al IC?

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Op woensdag 27 juni 2007 09:47 schreef Dwerfion het volgende:

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Noemt de ID-beweging iets wat uit 3 enzymen bestaat al IC?

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Op woensdag 27 juni 2007 10:08 schreef wijsneus het volgende:

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Dat is de _letterlijke_ definitie van IC. Minimaal drie delen waarbij het verwijderen van 1 van de delen het functioneren van het geheel stopt.

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Op woensdag 27 juni 2007 07:55 schreef bigore het volgende:

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Auw, als dit waar is en op de juiste manieren getoetst is/word kan dit een gigantische klap in de bek voor creationisten worden. Hopelijk horen we hier meer over.

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Op woensdag 27 juni 2007 11:10 schreef Monolith het volgende:
Of natuurlijk het feit dat Muller al in 1918 publiceerde over het idee dat evolutie zeer waarschijnlijk tot 'irreducible complexity' (hij noemde het interlocking complexity) zou moeten leiden.
Genetic Variablity, Twin Hybrids and Constant Hybrids, in a Case of Balanced Lethal Factors", by Hermann J Muller, in Genetics, Vol 3, No 5, Sept 1918, pp 422-499.

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Op woensdag 27 juni 2007 10:23 schreef Dwerfion het volgende:

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Waar haal je die drie vandaan? Ik zie wel ergens 'several' staan.

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Op woensdag 27 juni 2007 12:01 schreef wijsneus het volgende:

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Behe zegt inderdaad 'several' maar komt met voorbeelden van 'drie': Een kruk met drie poten is IC omdat hij niet functioneerd met twee poten. Een flagellum is 'motor, connector, and paddle'.

Ik heb dit verkeerd begrepen, i stand corrected

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Op donderdag 28 juni 2007 17:38 schreef Monolith het volgende:
[afbeelding]

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Scientists take step to making synthetic life

By Maggie Fox, Health and Science Editor
Thu Jun 28, 4:04 PM ET



WASHINGTON (Reuters) - Scientists have taken a first step toward making synthetic life by transferring genetic material from one bacterium into another, transforming the second microbe into a copy of the first.

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They intend to use their technique to custom-design bacteria to perform functions such as producing artificial fuel or cleaning up toxic waste, the researchers report in Friday's issue of the journal Science.

"This is equivalent to changing a Macintosh computer to a PC by inserting a new piece of software," Craig Venter, a genome pioneer who now heads his own institute in Rockville, Maryland, told reporters in a telephone briefing.

"I think eventually we could make artificial cells," Venter added. "This is a first step."

Venter has been trying for years to create a microbe from scratch. This is not quite it, but his team re-programmed one species of bacteria by adding in the genetic material from a closely related species.

They gene-engineered the replacement chromosome to resist an antibiotic and then flooded their experiment with the drug. The bacteria that survived all carried only the genes that had been spliced in.

They believe all the others simply died, but they are in fact not sure how the new DNA re-programmed some of the bacteria or what happened to the original DNA.

"I think that we don't know for certain how the donor genome takes over," Venter Institute researcher Ham Smith told reporters.

Nonetheless, Venter's team has applied for a patent on the process and they hope to exploit it industrially. Venter believes it will be relatively straightforward to build a new chromosome from scratch, one that performs the desired functions, to create a custom-made bacterium.

"What we are reporting in this Science paper is not anything about a synthetic organism," Venter said.

BOOTING UP LIFE

"It's a key enabling step so that once we have a synthetic chromosome we know it is now possible to boot that up. So synthetic biology itself and synthetic genomics is much closer to being proven," Venter added.

"We look forward to having fuels from genetically modified organisms within the next decade and perhaps in half that time."

The key to the experiment was using a very simple bacterium called Mycoplasma capricolum, which often infects goats. Bacteria do not have a nucleus as do cells from more complex organisms.

The research team injected a chromosome from a related species called Mycoplasma mycoides.

They do not know how well it worked but at least some of the M. capricolum were transformed into what looked and acted like M. mycoides.

The scientists concede it will be much more difficult to do this with more complex organisms, even bacteria, that have cell walls and all sorts of defensive mechanisms to keep out foreign

DNA.

A non-profit Canadian organization called the ETC Group expressed concern about the experiment and Venter's patent application. "We are extremely concerned about the breadth and implications of this patent and of its monopoly claims," the group's Jim Thomas said in an e-mail.

"We will be requesting that patent offices worldwide refuse this patent."

But Venter defended the patent. "At every stage of what the team has done here over the past several years, we have had to develop novel technologies and approaches that have not existed before because the field has not existed before," he said.