Evolutie. Deel XIV

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Op donderdag 9 augustus 2007 20:32 schreef SpecialK het volgende:
Waarom zou je geloof niet met een wetenschappelijke insteek kunnen bekijken? Volgens mij heeft spiritualiteit gewoon een biologische basis en is religie een sociologisch verschijnsel.

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Our results show that the mutation rate to new beneficial alleles is 1000 times as high as previously inferred in the same bacterial species (4, 16). The difference in results can be explained by the differences in the effective population size analyzed. If only very large effective sizes are analyzed, and the effect of clonal interference is not accounted for, then our estimates for Ua and E(sa) for the populations with Ne = 10^7 are similar to those previously obtained (Fig. 1B). However, if these estimates were close to the true values, then we would not expect to see the sweeps of beneficial mutations in the populations with lower Ne that we observed

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Op vrijdag 10 augustus 2007 12:09 schreef Monolith het volgende:
Interessante paper uit science over de mate van voordelige mutaties:
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Hele verhaal

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Op zondag 12 augustus 2007 15:23 schreef bigore het volgende:

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Jij bent toch gelovig? Is dit niet juist een "bewijs" voor evolutie? Ik bedoel, als de mutaties die als voordeel gekenmerkt worden 1000 x sneller zijn als we al dachten dan is dat een big plus voor de evolutietheorie?

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Op donderdag 9 augustus 2007 13:11 schreef Monolith het volgende:

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...en dat filosofen het er toch wel over eens zijn dat de wetenschap niets te zeggen heeft over geloof....

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Op donderdag 26 juli 2007 09:19 schreef Autodidact het volgende:

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Op zondag 12 augustus 2007 21:30 schreef wijsneus het volgende:

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Ik ben het echter met Dawkins eens: als een god interacteerd met deze wereld betekent dat deze invloed meetbaar moet zijn. Als een invloed meetbaar is moet dit met behulp van de wetenschappelijke methode onderzocht kunnen worden.

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Op dinsdag 14 augustus 2007 15:30 schreef Dwerfion het volgende:

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Precies. De conclusie dat een God aan het werk is geweest, zal echter altijd achterwege moeten biljven, omdat je geen niet-naturalistische verklaring kunt gebruiken in de wetenschap. De verste conclusie die wetenschap kan trekken is "We snappen het nog niet".

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Op dinsdag 14 augustus 2007 15:43 schreef Papierversnipperaar het volgende:

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Als God geen invloed heeft op de wereld, dan kan ie net zo goed niet bestaan.

Als ie wel invloed heeft dan moet dat meetbaar zijn.

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Op dinsdag 14 augustus 2007 15:50 schreef Dwerfion het volgende:

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Fijn als mensen mijn woorden nog even (deels) herhalen

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Simulations of biological evolution, in which computers are used to evolve systems toward a goal, often require many generations to achieve even simple goals. It is therefore of interest to look for generic ways, compatible with natural conditions, in which evolution in simulations can be speeded. Here, we study the impact of temporally varying goals on the speed of evolution, defined as the number of generations needed for an initially random population to achieve a given goal. Using computer simulations, we find that evolution toward goals that change over time can, in certain cases, dramatically speed up evolution compared with evolution toward a fixed goal. The highest speedup is found under modularly varying goals, in which goals change over time such that each new goal shares some of the subproblems with the previous goal. The speedup increases with the complexity of the goal: the harder the problem, the larger the speedup. Modularly varying goals seem to push populations away from local fitness maxima, and guide them toward evolvable and modular solutions. This study suggests that varying environments might significantly contribute to the speed of natural evolution. In addition, it suggests a way to accelerate optimization algorithms and improve evolutionary approaches in engineering.

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Op woensdag 15 augustus 2007 21:25 schreef Monolith het volgende:
Interessante resultaten in evolutie simulatie:
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bron

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Op donderdag 16 augustus 2007 02:06 schreef Papierversnipperaar het volgende:

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Hoe moeilijker je het maakt hoe beter het gaat!

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Op vrijdag 17 augustus 2007 00:06 schreef wijsneus het volgende:
Physicists Discover Inorganic Dust With Lifelike Qualities

An international team has discovered that, under the right conditions, particles of inorganic dust can become organized into helical structures. These structures can interact with one another in ways that are usually associated with organic compounds and with life. Not only do these helical strands interact in a counterintuitive way in which like can attract like, but they also undergo changes that are normally associated with biological molecules, such as DNA and proteins, say the researchers. For example, they can divide to form two copies of the original structure. These new structures can also interact to induce changes in their neighbors. And they can even evolve into yet more structures as less stable ones break down, leaving behind only the fittest structures in the plasma. 'These complex, self-organized plasma structures exhibit all the necessary properties to qualify them as candidates for inorganic living matter,' said the lead researcher. 'They are autonomous, they reproduce and they evolve.

http://www.sciencedaily.com/releases/2007/08/070814150630.htm

via slashdot

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The researchers hint that perhaps an inorganic form of life emerged on the primordial earth, which then acted as the template for the more familiar organic molecules we know today.

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Crystal Structure of an Ancient Protein: Evolution by Conformational Epistasis

The structural mechanisms by which proteins have evolved new functions are known only indirectly. We report x-ray crystal structures of a resurrected ancestral protein—the ~450 million-year-old precursor of vertebrate glucocorticoid (GR) and mineralocorticoid (MR) receptors. Using structural, phylogenetic, and functional analysis, we identify the specific set of historical mutations that recapitulate the evolution of GR’s hormone specificity from an MR-like ancestor. These substitutions repositioned crucial residues to create new receptor-ligand and intraprotein contacts. Strong epistatic interactions occur because one substitution changes the conformational position of another site. "Permissive" mutations—substitutions of no immediate consequence, which stabilize specific elements of the protein and allow it to tolerate subsequent function-switching changes—played a major role in determining GR’s evolutionary trajectory.

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Op donderdag 16 augustus 2007 07:55 schreef bigore het volgende:

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Nature always finds a way

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Op dinsdag 14 augustus 2007 15:43 schreef Papierversnipperaar het volgende:

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Als God geen invloed heeft op de wereld, dan kan ie net zo goed niet bestaan.

Als ie wel invloed heeft dan moet dat meetbaar zijn.

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Op vrijdag 31 augustus 2007 15:08 schreef wijsneus het volgende:
Drive by linkdump:

One Species' Genome Discovered Inside Another's

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Op vrijdag 17 augustus 2007 00:38 schreef wijsneus het volgende:
En dit vindt ik dan weer een boeiende doch vergezochte conclusie:
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Op maandag 3 september 2007 16:44 schreef Autodidact het volgende:
Walking With Cavemen

Iemand deze al gezien? Ziet er wel leuk uit.

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Op maandag 10 september 2007 13:40 schreef Rasing het volgende:
Een bijdrage van rapper Baas B aan het evolutiedebat: in een interview in het Veronica-magazine was de vraag: God of Darwin?

'Ik geloof wel in een God, maar ik geloof ook dat er buitenaardse wezens zijn. God of Darwin... het zijn voor mij allebei buitenaardse wezens.'

Ali_Kannibali en consorten: er zijn mensen met nóg minder verstand van evolutie.

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Op maandag 10 september 2007 14:37 schreef Monolith het volgende:
Laat die jongen het maar bij rappen houden, daar heeft hij tenminste wel verstand va..oh nee, toch niet.

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Op maandag 10 september 2007 14:39 schreef Rasing het volgende:

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Zelfs dat kan hij niet Misschien doet de natuurlijke selectie zijn werk wel, en hebben we over honderd jaar in ieder geval geen last van zijn nazaten.

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Op maandag 10 september 2007 15:11 schreef Autodidact het volgende:

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Mensen van zijn subspeciës zijn toch vrij goed in het voortplanten? Zo wordt de evolutietheorie als meme er door de natuurlijke selectie uitgefilterd....

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Scientists say velociraptor had feathers

WASHINGTON - Velociraptor, the terrifying predator made famous in the movie "Jurassic Park," appears to have had feathers in real life.

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A close study of a velociraptor forearm found in Mongolia shows the presence of quill knobs, bumps on the bone where the feathers anchor, researchers report in Friday's edition of the journal Science.

Dinosaurs are believed to be ancestors to modern birds. Evidence of feathered dinosaurs has been found in recent years, and now velociraptor can be added to that list.

"Finding quill knobs on velociraptor ... means that it definitely had feathers. This is something we'd long suspected, but no one had been able to prove," Alan Turner, lead author on the study and a graduate student of paleontology at the American Museum of Natural History and at Columbia University in New York, said in a statement.

The velociraptor the researchers studied was about three feet tall and weighed about 30 pounds. The size of these animals was exaggerated in the movie.

It had short forelimbs, compared to a modern bird, the researchers said, indicating it would not have been able to fly, even though it had feathers.

The feathers may have been useful for display, to shield nests, for temperature control or to help it maneuver while running, they said.

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20-09-2007


Deze schedel van de Keniaanse Homo Erectus (foto Reuters)

In Georgië zijn op de beroemde vindplaats Dmanisi veel skeletdelen van Homo erectus gevonden, 1,77 miljoen jaar oud. Ze wijzen uit dat Homo erectus in deze vroege tijd nog veel primitieve kenmerken had.

Tot nu toe gold de Keniase Nariokotomejongen als het typische Homo erectus-skelet. Sinds die vondst in 1984 van dat uitzonderlijk goed bewaard skelet van een tienjarige (gedateerd op 1,55 miljoen jaar geleden) geldt erectus als bijna modern: erg lang, met rechte ribbenkast en met alleen een kleiner brein dan tegenwoordig. Maar in het tijdschrift Nature van vandaag schetst een team van maar liefst achttien archeologen onder leiding van de Georgiër David Lordkipanidze (Nationaal Museum, Tiblisi) een ander beeld. De nu gevonden skeletdelen tonen een aantal duidelijke primitieve kenmerken heeft, die lijken op Australopithecus, de voorganger van Homo. Er zijn uit de evolutie van de mens vrij veel schedels gevonden, maar weinig ander botmateriaal.

Dmanisi stond al bekend om de vondst van relatief kleine H. erectus-schedels. Die worden soms toegewezen aan een aparte soort Homo georgicus, maar vrij algemeen wordt deze als nauw verwant of identiek aan H. erectus gezien. Een toewijzing van Homo georgicus aan de veel primitievere voorganger Homo habilis (ca 2 tot 1,5 miljoen jaar oud) heeft tot nu toe niet veel steun gekregen, al zullen de nu gevonden kenmerken die discussie weer aanwakkeren.

De lange onderbenen van de Dmanisi-mensen lijken op die van moderne mensen: heel geschikt om veel en ver mee te lopen. Maar hun bovenarmen vertonen duidelijk primitieve kenmerken. Wel is onduidelijk welke functie die minder gedraaide vorm van het bovenarmbeen heeft. Ook blijkt uit een Dmanisis-dijbeen dat de Georgische erectus iets korter was: een geschatte lengte van 145 tot 166 cm – tegen een geschatte (volwassen) lengte van de Nariokotome-erectus van 150 tot 169 cm.

(nrc)

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Santos et al.

Genetic isolation through time: allochronic differentiation of a phenologically atypical population of the pine processionary moth

Proceedings of the Royal Society B, Vol 274 No. 1612, pp. 935-941 (7 April 2007)

Allochronic speciation refers to a mode of sympatric speciation in which the differentiation of populations is primarily due to a phenological shift without habitat or host change. However, it has been so far rarely documented. The present paper reports on a plausible case of allochronic differentiation between sympatric populations of the pine processionary moth (PPM), Thaumetopoea pityocampa. The PPM is a Mediterranean insect with winter larval development. A phenologically atypical population with early adult activity and summer larval development was detected 10 years ago in Portugal. Mitochondrial and nuclear sequences strongly suggest that the ‘summer’ individuals are closely related to the sympatric winter population, while microsatellite data show a reduction in allelic richness, a distortion of allelic frequencies and significant genetic differentiation. Moreover, monitoring of adult flights suggests that reproductive activity does not overlap between the summer and winter populations. We postulate that the summer population appeared after a sudden phenological shift of some individuals of the sympatric winter population, leading to a founder effect and complete reproductive isolation. Given that the individuals showing this new phenology are subject to different selection pressures, the observed allochronic differentiation may rapidly lead to deeper divergence.

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Sparkman et al.

An empirical test of evolutionary theories for reproductive senescence and reproductive effort in the garter snake Thamnophis elegans

Proceedings of the Royal Society B, Vol 274 No. 1612, pp. 943-950 (7 April 2007)

Evolutionary theory predicts that differential reproductive effort and rate of reproductive senescence will evolve under different rates of external mortality. We examine the evolutionary divergence of age-specific reproduction in two life-history ecotypes of the western terrestrial garter snake, Thamnophis elegans. We test for the signature of reproductive senescence (decreasing fecundity with age) and increasing reproductive effort with age (increasing reproductive productivity per gram female) in replicate populations of two life-history ecotypes: snakes that grow fast, mature young and have shorter lifespans, and snakes that grow slow, mature late and have long lives. The difference between life-history ecotypes is due to genetic divergence in growth rate. We find reproductive success (live litter mass) increases with age in both ecotypes, but does so more rapidly in the fast-growth ecotype, (ii) reproductive failure increases with age in both ecotypes, but the proportion of reproductive failure to total reproductive output remains invariant, and (iii) reproductive effort remains constant in fast-growth individuals with age, but declines in slow-growth individuals. This illustration of increasing fecundity with age, even at the latest ages, deviates from standard expectations for reproductive senescence, as does the lack of increases in reproductive effort. We discuss our findings in light of recent theories regarding the phenomenon of increased reproduction throughout life in organisms with indeterminate growth and its potential to offset theoretical expectations for the ubiquity of senescence.

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Bragg and Wagner

Protein carbon content evolves in response to carbon availability and may influence the fate of duplicated genes

Proceedings of the Royal Society B, Vol 274 No. 1613, pp. 1063-1070 (22 April 2007)

Natural selection can influence even the lowest level of biological organization, the atomic composition of biological macromolecules. In analysing genome-scale gene expression data, we find that ancestral yeast strains preferentially express proteins with low carbon content during carbon limitation, relative to strains selected in the laboratory under carbon limitation. The likely reason is that the artificially selected strains acquire adaptations that refine their response to the limitation or partly circumvent the limiting condition. This finding extends previous work which shows that natural selection can act on the atomic costs of proteins. We also show that genes with high carbon and nitrogen content are less likely to have duplicates, indicating that atomic composition also plays a role in evolution by gene duplication. Taken together, our results contribute to the emerging view that protein atomic composition influences genome and transcriptome evolution.

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Op donderdag 4 oktober 2007 12:44 schreef Triggershot het volgende:
FOK! wiki/evolutie is ook behoorlijk outdated, als iemand van jullie daar naar wil kijken. [afbeelding]

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Op donderdag 4 oktober 2007 17:16 schreef Triggershot het volgende:

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Niet de inhoudelijkheid, maar laatste keer dat er aan gewerkt is.

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Op donderdag 4 oktober 2007 17:51 schreef Triggershot het volgende:

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Als de user en auteur daarmee content zijn, mij best

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For generations medical orthodoxy has maintained that the appendix is useless, warranting attention only for its tendency to become painfully inflamed and requiring swift removal. But now the reputation of this cul-de-sac in the human gut has been rehabilitated by a theory from a team of immunologists .

The US scientists found that the appendix acted as a "good safe house" for bacteria essential for healthy digestion, in effect re-booting the digestive system after the host has contracted diseases such as amoebic dysentery or cholera, which kill off helpful germs and purge the gut.
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The theory, developed by a team from Duke University Medical School, North Carolina, and published in the Journal of Theoretical Biology, has sent ripples through the scientific community. It "seems by far the most likely" explanation for the function of the appendix and "makes evolutionary sense", said Douglas Theobald, a professor of biochemistry at Brandeis University in Boston.

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Op dinsdag 9 oktober 2007 11:35 schreef Monolith het volgende:
De blinde darm is misschien toch niet helemaal zo nutteloos als gedacht:
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bron

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Writing this week in the journal Nature, Erez Lieberman, Jean-Baptiste Michel, and colleagues in Harvard's Program for Evolutionary Dynamics, led by Martin A. Nowak, conceive of linguistic development as an essentially evolutionary scheme: Just as genes and organisms undergo natural selection, words -- specifically, irregular verbs that do not take an "-ed" ending in the past tense -- are subject to powerful pressure to "regularize" as the language develops.

"Mathematical analysis of this linguistic evolution reveals that irregular verb conjugations behave in an extremely regular way -- one that can yield predictions and insights into the future stages of a verb's evolutionary trajectory," says Lieberman, a graduate student in applied mathematics in Harvard's School of Engineering and Applied Sciences and in the Harvard-MIT Division of Health Sciences and Technology, and an affiliate of Harvard's Program for Evolutionary Dynamics. "We measured something no one really thought could be measured, and got a striking and beautiful result."

http://www.sciencecodex.c(...)re_of_the_past_tense

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Op zondag 14 oktober 2007 14:44 schreef LB06 het volgende:
Wat zijn eigenlijk de verklaringen die biologen geven voor de macro-evolutie? D.w.z. van vis naar vogel? Bij biologie op het VWO heb ik min of meer geleerd dat dit een opstapeling van micro-mutaties onder druk van natuurlijke selectie is, maar ik heb laatst een boekje gelezen waarin werd beweerd dat dit niet mogelijk is en dat er dus een andere, al dan niet wetenschappelijke verklaring moet zijn hiervoor.

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Op zondag 14 oktober 2007 15:09 schreef Triggershot het volgende:
Ja, ja, ja ik weet het, strict wetenschappelijk, maar dees is leuk.
Ken Miller vs Harun Yahya

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Op zondag 14 oktober 2007 14:44 schreef LB06 het volgende:
Wat zijn eigenlijk de verklaringen die biologen geven voor de macro-evolutie? D.w.z. van vis dino naar vogel? Bij biologie op het VWO heb ik min of meer geleerd dat dit een opstapeling van micro-mutaties onder druk van natuurlijke selectie is, maar ik heb laatst een boekje gelezen waarin werd beweerd dat dit niet mogelijk is en dat er dus een andere, al dan niet wetenschappelijke verklaring moet zijn hiervoor.

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Writing Oct. 11, 2007 in the journal Nature, Howard Hughes Medical Institute investigator Sean B. Carroll and former UW-Madison graduate student Chris Todd Hittinger document how, over many generations, a single yeast gene divides in two and parses its responsibilities to be a more efficient denizen of its environment. The work illustrates, at the most basic level, the driving force of evolution.

"This is how new capabilities arise and new functions evolve," says Carroll, one of the world's leading evolutionary biologists. "This is what goes on in butterflies and elephants and humans. It is evolution in action."

The work is important because it provides the most fundamental view of how organisms change to better adapt to their environments. It documents the workings of natural selection, the critical idea first posited by Charles Darwin where organisms accumulate random variations, and changes that enhance survival are "selected" by being genetically transmitted to future generations.

The new study replayed a set of genetic changes that occurred in a yeast 100 million or so years ago when a critical gene was duplicated and then divided its nutrient processing responsibilities to better utilize the sugars it depends on for food.

"One source of newness is gene duplication," says Carroll.

"When you have two copies of a gene, useful mutations can arise that allow one or both genes to explore new functions while preserving the old function. This phenomenon is going on all the time in every living thing. Many of us are walking around with duplicate genes we're not aware of. They come and go."

In short, says Carroll, two genes can be better than one because redundancy promotes a division of labor. Genes may do more than one thing, and duplication adds a new genetic resource that can share the workload or add new functions. For example, in humans the ability to see color requires different molecular receptors to discriminate between red and green, but both arose from the same vision gene.

The difficulty, he says, in seeing the steps of evolution is that in nature genetic change typically occurs at a snail's pace, with very small increments of change among the chemical base pairs that make up genes accumulating over thousands to millions of years.

To measure such small change requires a model organism like simple brewer's yeast that produces a lot of offspring in a relatively short period of time. Yeast, Carroll argues, are perfect because their reproductive qualities enable study of genetic change at the deepest level and greatest resolution because researchers can produce and quickly count a large number of organisms. The same work in fruit flies, one of biology's most powerful models, would require "a football stadium full of flies" and years of additional work, Carroll explains.

"The process of becoming better occurs in very small steps. When compounded over time, these very small changes make one group of organisms successful and they out-compete others," according to Carroll.

The new study involved swapping out different regions of the yeast genome to assess their effects on the performance of the twin genes, as well as engineering in the gene from another species of yeast that had retained only a single copy.

"We retraced the steps of evolution," the Wisconsin biologist explains.

The work shows in great detail how the ancestral gene gained efficiency through duplication and division of labor.

"They became optimally connected in that job. They're working in cahoots, but together they are better at the job the ancestral gene held," Carroll says. "Natural selection has taken one gene with two functions and sculpted an assembly line with two specialized genes."

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Charlesworth, J. and Eyre-Walker, A. (2007) The other side of the nearly neutral theory, evidence of slightly advantageous back-mutations. PNAS, advanced online publication.

We argue that if there is a category of slightly deleterious mutations, then there should be a category of slightly advantageous back-mutations. We show that when there are both slightly deleterious and advantageous back-mutations, there is likely to be an increase in the rate of evolution after a population size expansion. This increase in the rate of evolution is short-lived. However, we show how its signature can be captured by comparing the rate of evolution in species that have undergone population size expansion versus contraction. We test our model by comparing the pattern of evolution in pairs of island and mainland species in which the colonization event was either island-to-mainland (population size expansion) or mainland-to-island (contraction). We show that the predicted pattern of evolution is observed.

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Bergthorsson, U. et al. (2007) Ohno's dilemma: Evolution of new genes under continuous selection. PNAS, advanced online publication.

New genes with novel functions arise by duplication and divergence, but the process poses a problem. After duplication, an extra gene copy must rise to sufficiently high frequency in the population and remain free of common inactivating lesions long enough to acquire the rare mutations that provide a new selectable function. Maintaining a duplicated gene by selection for the original function would restrict the freedom to diverge. (We refer to this problem as Ohno's dilemma). A model is described by which selection continuously favors both maintenance of the duplicate copy and divergence of that copy from the parent gene. Before duplication, the original gene has a trace side activity (the innovation) in addition to its original function. When an altered ecological niche makes the minor innovation valuable, selection favors increases in its level (the amplification), which is most frequently conferred by increased dosage of the parent gene. Selection for the amplified minor function maintains the extra copies and raises the frequency of the amplification in the population. The same selection favors mutational improvement of any of the extra copies, which are not constrained to maintain their original function (the divergence). The rate of mutations (per genome) that improve the new function is increased by the multiplicity of target copies within a genome. Improvement of some copies relaxes selection on others and allows their loss by mutation (becoming pseudogenes). Ultimately one of the extra copies is able to provide all of the new activity.

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NIJMEGEN - Nederlandse en IJslandse onderzoekers hebben min of meer bij toeval de genetische varianten gevonden, die bepalen welke oog-, haar- en huidskleur een Europees mens heeft. Tot nu toe kon op basis van DNA-materiaal alleen geslacht en ras van een persoon worden vastgesteld.

De onderzoeksgroep, die in Nederland is gevestigd in het Universitair Medisch Centrum St Radboud (UMC) in Nijmegen, is eigenlijk op zoek naar genetische determinanten van prostaat- en borstkanker. In dit onderzoek zijn toevallig de genvarianten aangetroffen, die uiterlijke kenmerken van Europees mensen bepalen.

De vondst van de genetische variant is volgens de onderzoekers onder meer belangrijk voor onderzoek naar misdrijven. Uitsluitend op basis van aangetroffen DNA-materiaal kan nu behalve het geslacht worden vastgesteld welke haarkleur de verdachte heeft, wat voor soort huid en welke kleur ogen.

Eén gevonden genetische variant bepaalt het in Europa veelvoorkomende blonde haar met blauwe ogen. Een tweede variant zorgt voor een lichte huid met sproeten en bruin haar. Er zijn tevens varianten gevonden die zorgen voor sproeten, een huid die gemakkelijk verbrandt en blauwe ogen. Eerder waren al genen gevonden die rood haar, een lichte huid en sproeten veroorzaken.

De onderzoekers stellen dat er veel genetisch materiaal is betrokken bij het bepalen van de kleuren die iemands uiterlijk heeft. Dat verklaart tevens waarom het Europese ras zoveel verschillende types telt.

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Pigliucci, M. (2007) Do we need an extended evolutionary synthesis. Evolution, advanced online publication

The Modern Synthesis (MS) is the current paradigm in evolutionary biology. It was actually built by expanding on the conceptual foundations laid out by its predecessors, Darwinism and neo-Darwinism. For sometime now there has been talk of a new Extended Evolutionary Synthesis (EES), and this article begins to outline why we may need such an extension, and how it may come about. As philosopher Karl Popper has noticed, the current evolutionary theory is a theory of genes, and we still lack a theory of forms. The field began, in fact, as a theory of forms in Darwin's days, and the major goal that an EES will aim for is a unification of our theories of genes and of forms. This may be achieved through an organic grafting of novel concepts onto the foundational structure of the MS, particularly evolvability, phenotypic plasticity, epigenetic inheritance, complexity theory, and the theory of evolution in highly dimensional adaptive landscapes.

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Let me again be clear on a fundamental point underlying this whole discussion: one can reasonably argue that none of this contradicts any tenet of the MS, although it seems to me at least reasonable to concede that the new concepts and empirical findings I have briefly outlined above may eventually force a shift of emphasis away from the population genetic-centered view of evolution that characterizes the MS. On the other hand, to attempt to go further and state that there is not much new here and that all of this is already part of the MS, implicitly or not, would be intellectually disingenuous and historically inaccurate.

What I think will happen over the next several years is a process analogous to the MS itself: not a paradigm shift a la Kuhn (1970), but another series of complex developments that build on its three major predecessors: Darwinism, neo-Darwinism, and the MS itself. This is not the place for a philosophical analysis of whether paradigm shifts ever happen, even in astronomy and physics—Kuhn's original sources for his examples. Nevertheless, I argue that biology has, in fact, never undergone a true paradigm shift, and very likely never will. If one really wishes to identify anything in biology equivalent to the move from the Ptolemaic to the Copernican system, then one has to go back in time before Darwin: we have to reach as far back as the early 19th century transformation from a natural theological to a natural philosophical understanding of the history and diversity of life, to which Darwin greatly contributed but that he did not initiate, and consider the earlier evolutionary works of Lamarck, Chambers, and Erasmus Darwin. Perhaps truly incommensurable paradigm shifts only happen when a proto-science turns into a mature science, as astronomy did during the 16th and early 17th centuries (Copernicus and Galileo), physics during the 17th and 18th centuries (Galileo and Newton), and both biology and geology during the 19th century (Darwin and Lyell). Once a science is established, conceptual frameworks tend to expand, more than being replaced, and even when replacement can be argued for (as in the transition from Newtonian to relativistic mechanics at the onset of the 20th century), the new model is not incommensurable with the older, as the latter can be interpreted as a limit case or approximation of the new and broader one.

Be that as it may, the proof for the EES is in the pudding: it is up to those who advocate a significant expansion of theoretical biology (in the broader sense of conceptual understanding of the discipline's foundations) to show tangible progress. It would be a shame, however, to curtail or dismiss the discussion in its infancy. Evolutionary biologists, whether they advocate the MS or the EES, have a lot of work to do to make sense of a rapidly growing amount of findings in molecular, developmental, and organismal biology. Instead of looking forward to retirement, we should appreciate what a truly exciting time is awaiting us all.

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Op woensdag 24 oktober 2007 14:49 schreef Monolith het volgende:
Tijd voor een hernieuwd raamwerk in de evolutionaire biologie?
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Conclusie van het artikel:
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Interessante ontwikkeling m.i.

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Op woensdag 24 oktober 2007 15:01 schreef Papierversnipperaar het volgende:

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Ik mis de dramatiek. We gaan verder waar we gebleven waren, zo te lezen. Mis ik iets?

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Op zondag 28 oktober 2007 22:00 schreef Triggershot het volgende:
'Menselijk ras evolueert in twee soorten'

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Op zondag 28 oktober 2007 22:00 schreef Triggershot het volgende:
'Menselijk ras evolueert in twee soorten'

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In the summer of 2006 I was commissioned by Bravo Television to write an essay on the future of human evolution. The essay was intended as a 'science fiction' way of illustrating some aspects of evolutionary theory.

Bravo then sent out a press release on the essay, but did not release the essay itself. As a result, a wildly distorted version of what I had written ended up being reported as ‘science fact’ in the media. I do not endorse the content of these media reports. Here's the actual essay.

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Divided by oceans of empty space, our distant descendants would find themselves in a similar situation. We should expect to see different species of humans adapting to their local planetary environments. Descendants who end up on big, slow, heavy, dark cold planets might come to resemble modern day Inuits: short, stocky, with slow metabolisms, longer circadian rhythms, and pale skin. Those who end up on small, fast, light, warm planets might come to resemble the fabled Nubians: tall, thin, with fast metabolisms, shorter circadian rhythms, and darker skin. In all cases, we should expect the different
populations of humans to adapt their metabolism to the peculiarities of the local foodstuffs, and the local atmosphere; and to adapt their immune systems to local diseases. Under these conditions we would see the evolution of new species of humans, perhaps named after their celestial location: perhaps Homo andromeda, Homo betelgeuse. Our own species, Homo sapiens, would be long gone.

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The future
So, these might be some of the highs and lows of human evolution over the next million years. But remember, that there is nothing inevitable about the evolutionary process. It is not aiming at anything, it has no goals, and no inertia. What evolves will be a product of the mutations that arise, and the circumstances in which they find themselves. To the extent that we will be able to invent new genes, and to create our own conditions, we have some control over our future. In this sense, the future is not a place that we will go to, it is a thing that we will build.

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Modern-day birds have a highly specialised respiratory system, made up of a small rigid lung and around nine air sacs.

The bellows-like movement of the sternum and ribs moves air through the system.

Bony projections on the ribcage known as uncinate processes play an important role in both respiration and locomotion.

The small bones act as levers to move the ribs and sternum during breathing. They have become adapted in different types of birds to deal with different ways of getting around.

The bones are shortest in runners like emus that don't need large breast muscles for flight, intermediate in flying birds and longest in divers such as the penguin.

The Manchester team studied a wealth of fossil remains of dinosaurs and extinct birds such as Archaeopteryx, and compared these with skeletons of living birds.

They found that uncinate processes are also found both in the extinct ancestors of birds, the theropod dinosaurs, and in modern species.

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Op zaterdag 10 november 2007 20:37 schreef Karmijne het volgende:
Wat verklaart het blonde haar van Europeanen en dan met name Scandinaviers?

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Op zaterdag 10 november 2007 20:47 schreef Iblardi het volgende:

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Dat was een tijdje terug in het nieuws: het zou om een vrij recente (c. 10.000 jaar geleden) aanpassing gaan die het gevolg was van strengere seksuele selectie van vrouwelijke partners. Zie http://www.timesonline.co.uk/tol/news/uk/article735078.ece.

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Op zaterdag 10 november 2007 20:47 schreef Iblardi het volgende:

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Dat was een tijdje terug in het nieuws: het zou om een vrij recente (c. 10.000 jaar geleden) aanpassing gaan die het gevolg was van strengere seksuele selectie van vrouwelijke partners. Zie http://www.timesonline.co.uk/tol/news/uk/article735078.ece.

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Op zaterdag 10 november 2007 20:55 schreef Karmijne het volgende:

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hmm, hij opent niet...

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Op zaterdag 10 november 2007 21:12 schreef Iblardi het volgende:

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Probeer het eens zo: http://www.timesonline.co.uk/tol/news/uk/article735078.ece
Macht der gewoonte, had afgesloten met een punt.

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Op donderdag 15 november 2007 09:53 schreef wijsneus het volgende:
Voor een goede beschrijving van Macro Evolutie en het failliet van ID zou je de getuigenis van Kevin Padian in Kitzmiller v. Dover moeten lezen.

Long read - good stuff.

http://www.sciohost.org/ncse/kvd/Padian/Padian_transcript.html

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Q And using your definition, intelligent design is a scientific theory, correct?

A Yes.

Q Under that same definition astrology is a scientific theory under your definition, correct?

A Under my definition, a scientific theory is a proposed explanation which focuses or points to physical, observable data and logical inferences. There are many things throughout the history of science which we now think to be incorrect which nonetheless would fit that -- which would fit that definition. Yes, astrology is in fact one, and so is the ether theory of the propagation of light, and many other -- many other theories as well.

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Friesen, V.L. et al. (2007) Sympatric speciation by allochrony in a seabird. PNAS, advance online publication

The importance of sympatric speciation (the evolution of reproductive isolation between codistributed populations) in generating biodiversity is highly controversial. Whereas potential examples of sympatric speciation exist for plants, insects, and fishes, most theoretical models suggest that it requires conditions that are probably not common in nature, and only two possible cases have been described for tetrapods. One mechanism by which it could occur is through allochronic isolation—separation of populations by breeding time. Oceanodroma castro (the Madeiran or band-rumped storm-petrel) is a small seabird that nests on tropical and subtropical islands throughout the Atlantic and Pacific Oceans. In at least five archipelagos, different individuals breed on the same islands in different seasons. We compared variation in five microsatellite loci and the mitochondrial control region among 562 O. castro from throughout the species' range. We found that sympatric seasonal populations differ genetically within all five archipelagos and have ceased to exchange genes in two. Population and gene trees all indicate that seasonal populations within four of the archipelagos are more closely related to each other than to populations from the same season from other archipelagos; divergence of the fifth sympatric pair is too ancient for reliable inference. Thus, seasonal populations appear to have arisen sympatrically at least four times. This is the first evidence for sympatric speciation by allochrony in a tetrapod, and adds to growing indications that population differentiation and speciation can occur without geographic barriers to gene flow.

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Op vrijdag 16 november 2007 13:15 schreef ATuin-hek het volgende:
Wellicht ook interessant
http://www.nu.nl/news/131(...)k_op_land_leven.html

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They produce eggs which remain in the bottom mud to survive when their pools dry out, so their eggs can be stored dry at room temperature for many years.

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Op vrijdag 23 november 2007 09:21 schreef SpecialK het volgende:

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http://www.nu.nl/news/132(...)_steeds_kleiner.html

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Op vrijdag 23 november 2007 10:17 schreef Bensel het volgende:

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damn, je was me te snel af..

Vind het trouwens wel een heel mooi voorbeeld hoe dat de natuur nu reageert op de bedreiging die wij als mensen vormen voor andere diersoorten dmv evolutie. Menselijke selectie is in dit geval gelijk aan natuurlijke selectie.

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The cane toads go bump in the night. I hear them banging as they misjudge where my hotel door ends and the forest begins. The force of a large toad knocking wood is substantial. But the force with which the toads, which are native to Central America, have hit Australia is even greater. Brought to Queensland in 1935 to combat beetles infesting sugarcane fields, the toads have spread out from their point of entry like the shock waves of a bomb, warty legs and oversize tongues jettisoned into every conceivable ecological crack.

Recent research by Ben Phillips and his collaborators at the University of Sydney has shown that the toads are evolving as they spread, perfecting their ability to adapt to the Australian landscape. The toads at the front edge of the invasion now have smaller bodies, reduced toxicity and relatively longer legs, apparently because individuals with those traits were having greater success. The native fauna has evolved in response: the mouths of some snake species are getting smaller, for instance, because so many of the snakes with big mouths were eating the poisonous cane toads and dying off.

Such examples are changing scientists’ views of the speed of evolution. The process was long considered to be slow, even lumbering. Increasingly, though, researchers are observing evolution in action. You may be familiar with the examples of the evolution of drug-resistant bacteria or agricultural pests. Microbes and pests may change the fastest, but they are not unique.

We see rapid evolution most often where some force (often us) has given it a jump start by suddenly and dramatically altering an organism’s environment. Rats have developed smaller bodies when introduced to islands. Trophy fish have also adopted smaller body sizes in response to fishers’ preference for big fish (which, if killed, do not breed). Mayflies in streams where trout were released now forage at night to avoid the fast-swimming predators. Many hundreds of herbivorous species have switched to novel, sometimes toxic, food sources introduced by humans and have come to specialize in consuming those new resources. Various native species have evolved in response to newly arrived competitors. Cedar trees have begun making toxins to protect themselves from being eaten by deer now roaming in their formerly benign habitats. Mussels in New England have evolved the ability to detect invasive green crabs and produce thicker shells where the crabs are present.

Most of these changes appear to have resulted from natural selection: organisms that by chance had some genetic trait that helped them thrive in the face of a new stress were favored, and subsequently they reproduced successfully and spread the helpful trait to future generations. But some evolutionary changes we see may simply be the result of genetic drift (random genetic changes that accrue over time).

The more we look, the more we can observe evolutionary changes that are fast enough to be seen during the course of a single study. A Ph.D. student might, in the five or so years of a dissertation project, realistically see the development of new species, whether in real time or using genetic tools to reconstruct evolutionary history. As house mice and rats have spread with us around the world, they have speciated into forms best adapted to the different regions where they live. In the northeastern U.S., a species of fly has evolved to feed on a species of honeysuckle introduced to North America less than 250 years ago. Although the new fly is a hybrid between two existing species, it can mate with neither one and maintains viable populations of its own.

People tend to imagine evolution as acting only on long-extinct creatures such as the dinosaurs, but the flensing knives of natural selection and the random pushes and pulls of genetic drift are still at work today. We see a red oak tree in our backyard or a cane toad at our hotel-room door, but the names fool us. These species are not the same this year and next. Although the evolution we observe in real time will not suddenly give us dinosaurs, it is still a process to be reckoned with. Give natural selection a few individuals of any species, and it will work the same way in a waste pool as it does in Yellowstone National Park. Nature abhors a vacuum, but nearly anything else will do.

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Op vrijdag 23 november 2007 10:17 schreef Bensel het volgende:

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damn, je was me te snel af..

Vind het trouwens wel een heel mooi voorbeeld hoe dat de natuur nu reageert op de bedreiging die wij als mensen vormen voor andere diersoorten dmv evolutie. Menselijke selectie is in dit geval gelijk aan natuurlijke selectie.

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Op vrijdag 23 november 2007 10:52 schreef Monolith het volgende:

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De mens is in deze natuurlijk ook gewoon een roofdier, dus zo gek is dat niet. Is dit trouwens wel zo recent? Ik probeerde even de wetenschappelijke publicatie te vinden en kwam dit artikel uit 2005 tegen waarin hetzelfde wordt beweerd. Dit artikeltje bekijkt de invloed van de mens in een bredere context en vindt nog veel meer voorbeelden van snelle aanpassing door de invloed van de mens:
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Op vrijdag 23 november 2007 09:21 schreef SpecialK het volgende:

http://www.nu.nl/news/132(...)_steeds_kleiner.html

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Op vrijdag 23 november 2007 13:23 schreef Papierversnipperaar het volgende:

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Dat verklaard waarom er geen fossielen zijn van "tussenvormen"

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Op maandag 26 november 2007 18:13 schreef Autodidact het volgende:

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Wat zeg je nou? Dat er geen fossielen zijn van zgn. tussenvormen?

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Op maandag 26 november 2007 18:24 schreef Papierversnipperaar het volgende:

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Schijnt een kritiekpuntje te zijn van creationisten, dat ze het fossielenbestand niet compleet genoeg vinden.

Maar ondanks dat we niet alle schilderijen van Rembrandt hebben vinden we het toch een goed schilder.

TOCH?!?

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Op maandag 26 november 2007 18:24 schreef Papierversnipperaar het volgende:

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Schijnt een kritiekpuntje te zijn van creationisten, dat ze het fossielenbestand niet compleet genoeg vinden.

Maar ondanks dat we niet alle schilderijen van Rembrandt hebben vinden we het toch een goed schilder.

TOCH?!?

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Op maandag 26 november 2007 20:20 schreef Autodidact het volgende:

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Je neemt nu de de claims van creationisten voor waar aan. Niet doen . Dat was misschien een enigszins geldig argument in Darwins tijd, toen er bijna geen fossielen waren, maar nu niet meer.

Zie bijvoorbeeld de evolutie van de walvis, waarvan de volgende "tussensoorten" bekend zijn. Nu kun je altijd zeggen "we hebben het fossiel van een dier tussen de Takracetus en de Gaviocetus niet&quot. Klopt, maar dan maak je bij elke vondst twee nieuwe "missing links". Maar gelukkig hoef je niet alle fossielen gevonden te hebben voordat de evolutietheorie geloofwaardigheid heeft, net zoals je niet alle mogelijke rekensommen hoeft te maken om te weten dat algebra geldige wiskunde is.

[ afbeelding ]

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Op dinsdag 27 november 2007 15:00 schreef bigore het volgende:

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De stap tussen dalanistus en rodho is wel erg groot eigenlijk

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Op vrijdag 23 november 2007 13:23 schreef Papierversnipperaar het volgende:

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Dat verklaard waarom er geen fossielen zijn van "tussenvormen"

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Op dinsdag 27 november 2007 17:47 schreef boyv het volgende:

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Ik las net toevallig in een schoolboek dat er wel tussenvormen zijn gevonden. Zal het zo even opzoeken en citeren.

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TOPEKA, KS—In response to a Nov. 7 referendum, Kansas lawmakers passed emergency legislation outlawing evolution, the highly controversial process responsible for the development and diversity of species and the continued survival of all life.

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The sweeping new law prohibits all living beings within state borders from being born with random genetic mutations that could make them better suited to evade predators, secure a mate, or, adapt to a changing environment. In addition, it bars any sexual reproduction, battles for survival, or instances of pure happenstance that might lead, after several generations, to a more well-adapted species or subspecies.

Violators of the new law may face punishments that include jail time, stiff fines, and rehabilitative education and training to rid organisms suspected of evolutionary tendencies. Repeat offenders could face chemical sterilization.

To enforce the law, Kansas state police will be trained to investigate and apprehend organisms who exhibit suspected signs of evolutionary behavior, such as natural selection or speciation. Plans are underway to track and monitor DNA strands in every Kansan life form for even the slightest change in allele frequencies.

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"If Earth's species were meant to change over successive generations through physical modifications resulting from the adaptation to environmental challenges, then God would have given them the genetic predisposition to select mates and reproduce based on their favorable heritable traits and their ability to thrive under changing conditions so that these advantageous qualities would be passed down and eventually encoded into the DNA of each generation of offspring," Olathe public school teacher and creationist Joyce Eckhardt said. "It's just not natural."

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"If Kansans want to ban evolution, that is their right, but they must understand that we rely on a certain flexibility in the natural order of things to be able to deliver healthy food products to millions of Americans," said Carl Casale, a vice president with the agricultural giant Monsanto. "We're not talking about playing God here. We are talking about succeeding in the competitive veggie-burger market."

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Gemummificeerde dinosaurus ontdekt
Uitgegeven: 3 december 2007 06:28

WASHINGTON - Een tiener heeft de mogelijk compleetste dinosauriër tot nu toe ontdekt. Het gaat om een gedeeltelijk gemummificeerde hadrosaur. Van het fossiele dier is weefsel bewaard gebleven, misschien zelfs zacht weefsel.

De intacte huid met schubben toont bewijzen van strepen, aldus een wetenschapper van de universiteit in het Britse Manchester maandag na maandenlang onderzoek. De hadrosaur blijkt gespierder te zijn geweest dan was aangenomen.

De destijds 17-jarige Tyler Lyson trof de 67 miljoen jaar oude overblijfselen in 2000 aan op het land van een oom in het Amerikaanse North Dakota.

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Op maandag 3 december 2007 06:57 schreef barthol het volgende:
ANP bericht via Nu.nl:
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Uiteraard zijn er ook iets uitgebreidere (engelstalige) berichten over via Associated Press en Reuters

Hmmm, zou het eventueel de mogelijkheid geven om (een deel van) het DNA van die Hadrosaurus te onderzoeken?

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Time long ago transformed Dakota's soft tissue into mineralized rock, preserving it for the ages.
"It's a dinosaur that was turned into stone, essentially," said Lyson, 24, now a graduate student in paleontology at Yale University.
http://www.washingtonpost(...)80.html?hpid=topnews