Daarom Evolutie #11

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Op zondag 10 september 2006 12:19 schreef stinkyduiker het volgende:
Mutaties ontstaan door "foutjes" in het repliceren van DNA (toch?) en mutaties zijn veel vaker slecht dan goed voor het organisme. Als je hier verder op ingaat zal een organisme met een systeem wat minder "foutjes" maakt een selectief voordeel krijgen.
Het lijkt me dat er steeds minder mutaties plaats gaan vinden en dat evolutie dus eigenlijk steeds langzamer wordt, klopt dit?

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Early Bird Used Four Wings to Fly

The earliest known bird had flight feathers on its legs that allowed it to use its hindlimbs as an extra pair of wings, a new study finds.

The finding, detailed in the current issue of the journal Paleobiology, supports the theory that early birds learned to glide and parachute from trees before achieving full-fledged flight.

"This paper puts forward some of the strongest evidence yet that birds descended from arboreal parachuters and gliders, similar to flying squirrels," said study author Nick Longrich, a doctoral student a the University of Calgary in Canada.

The missing link
Archaeopteryx was a crow-sized animal that lived about 150 million years ago and which looked like a cross between a bird and a dinosaur. It had feathers and a wishbone like birds but also reptilian features like a long bony tail, claws and teeth.

When the first Archaeopteryx fossil was discovered in 1861, it caused a sensation because it was the kind of transitional animal that the British naturalist Charles Darwin predicted in his theory of evolution only a few years earlier.

In 1877, a second Archaeopteryx specimen discovered in Germany showed a curious feature: long feathers covering its hindlimbs. For more than a century, the feathers were dismissed by most scientists as being simple, albeit unusual-looking, insulating body feathers--called "contour" feathers--that didn't play a role in the animal's flight.

But then, beginning in 2002, paleontologists began finding four-winged dinosaurs in China with hindlimb feathers that appeared to be important for gliding and perhaps even flying. In light of the new findings, Longrich decided it was time that Archaeopteryx was reexamined.

Flying with four wings

Longrich examined hindlimb feathers on five Archaeopteryx fossils using a dissecting microscope and found that the feathers had features typical of flight feathers in modern birds, including curved shafts, a self-stabilizing overlap pattern and vane asymmetry, in which the parallel row of barbs that make up the feather are longer on one side than the other.

Next, Longrich used standard mathematical models for flight to calculate how an extra pair of wings would have affected Archaeopteryx's flight. He found that hindlimb feathers would have allowed Archaeopteryx to fly slower and to make sharper turns.

Sharper turns would have improved Archaeopteryx's abilities to maneuver in pursuit of prey, to escape predators and to fly through the cluttered branches of trees and bushes. And the ability to fly slower meant Archaeopteryx had more time to avoid obstacles and to make safer landings.

Longrich speculates that the hindlimb feathers might have served other roles in addition to flight. Like modern pigeons, kittiwakes and vultures, Archaeopteryx's hindlimb feathers might have acted as airbrakes, or perhaps stabilizers, control surfaces or flaps, Longrich writes.

Scientists don't know when in their evolutionary history birds switched from a "four winged" design to a two-wing one, but it's thought that hindlimb wings were sacrificed in order to free up legs for other functions, such as running, swimming and catching prey.

"The idea that a multi-winged Archaeopteryx has been around for more than a century, but it has received little attention," Longrich said. "I believe one reason for this is that people tend to see what they want or expect to see. Everybody knows that birds don't have four wings, so we overlooked them even when they were right under our noses."

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Michael Shermer: Darwin on the Right
Why Christians and conservatives should accept evolution

According to a 2005 Pew Research Center poll, 70 percent of evangelical Christians believe that living beings have always existed in their present form, compared with 32 percent of Protestants and 31 percent of Catholics. Politically, 60 percent of Republicans are creationists, whereas only 11 percent accept evolution, compared with 29 percent of Democrats who are creationists and 44 percent who accept evolution. A 2005 Harris Poll found that 63 percent of liberals but only 37 percent of conservatives believe that humans and apes have a common ancestry. What these figures confirm for us is that there are religious and political reasons for rejecting evolution. Can one be a conservative Christian and a Darwinian? Yes. Here's how.

1. Evolution fits well with good theology. Christians believe in an omniscient and omnipotent God. What difference does it make when God created the universe--10,000 years ago or 10,000,000,000 years ago? The glory of the creation commands reverence regardless of how many zeroes in the date. And what difference does it make how God created life--spoken word or natural forces? The grandeur of life's complexity elicits awe regardless of what creative processes were employed. Christians (indeed, all faiths) should embrace modern science for what it has done to reveal the magnificence of the divine in a depth and detail unmatched by ancient texts.

2. Creationism is bad theology. The watchmaker God of intelligent-design creationism is delimited to being a garage tinkerer piecing together life out of available parts. This God is just a genetic engineer slightly more advanced than we are. An omniscient and omnipotent God must be above such humanlike constraints. As Protestant theologian Langdon Gilkey wrote, "The Christian idea, far from merely representing a primitive anthropomorphic projection of human art upon the cosmos, systematically repudiates all direct analogy from human art." Calling God a watchmaker is belittling.

3. Evolution explains original sin and the Christian model of human nature. As a social primate, we evolved within-group amity and between-group enmity. By nature, then, we are cooperative and competitive, altruistic and selfish, greedy and generous, peaceful and bellicose; in short, good and evil. Moral codes and a society based on the rule of law are necessary to accentuate the positive and attenuate the negative sides of our evolved nature.

4. Evolution explains family values. The following characteristics are the foundation of families and societies and are shared by humans and other social mammals: attachment and bonding, cooperation and reciprocity, sympathy and empathy, conflict resolution, community concern and reputation anxiety, and response to group social norms. As a social primate species, we evolved morality to enhance the survival of both family and community. Subsequently, religions designed moral codes based on our evolved moral natures.

5. Evolution accounts for specific Christian moral precepts. Much of Christian morality has to do with human relationships, most notably truth telling and marital fidelity, because the violation of these principles causes a severe breakdown in trust, which is the foundation of family and community. Evolution describes how we developed into pair-bonded primates and how adultery violates trust. Likewise, truth telling is vital for trust in our society, so lying is a sin.

6. Evolution explains conservative free-market economics. Charles Darwin's "natural selection" is precisely parallel to Adam Smith's "invisible hand." Darwin showed how complex design and ecological balance were unintended consequences of competition among individual organisms. Smith showed how national wealth and social harmony were unintended consequences of competition among individual people. Nature's economy mirrors society's economy. Both are designed from the bottom up, not the top down.

Because the theory of evolution provides a scientific foundation for the core values shared by most Christians and conservatives, it should be embraced. The senseless conflict between science and religion must end now, or else, as the Book of Proverbs (11:29) warned: "He that troubleth his own house shall inherit the wind."

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Op dinsdag 3 oktober 2006 23:01 schreef Autodidact het volgende:

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Op woensdag 4 oktober 2006 12:49 schreef speknek het volgende:

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Hij valt in de Sociaal Darwinisme valkuil.

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Op woensdag 4 oktober 2006 12:53 schreef Autodidact het volgende:
Hoezo? De evolutietheorie verklaart sociale verschijnselen zoals moraal...

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Scientists find more bones of big camels

DAMASCUS, Syria - Hunters stalked giant camels as tall as some modern-day elephants in the Syrian desert tens of thousands of years ago and archaeologists behind the find are wondering where the camels came from and what caused them to die off.

The enormous beasts existed about 100,000 years ago and more of the bones, first discovered last year, have been found this year in the sands about 150 miles north of the capital, Damascus.

The animal, branded the "Syrian Camel" by its Swiss and Syrian discoverers, stood between three and four yards high — about twice the size of latter-day camels and the height at the shoulder of many African elephants.

"The camel is a dromedary but extremely big and extremely tall — about double the size of a modern day camel," said Jean-Marie Le Tensorer, who led the Swiss side of the team.

The camels did not appear to have been bred by humans as beasts of burden, the scientists said, raising questions about its provenance — and disappearance.

"What we want to know now is: where did it come from, and why did it disappear never to be seen again? Was it migrating from Asia to Africa?" said the team's Syrian leader, Heba al-Sakhel.

Le Tensorer said humanoid bones were discovered at a nearby site and stone tools used by early humans were found with the camel's bones, which are thought to be up to 100,000 years old.

"The bones — a fragment of an arm and a tooth — are, of course, of the hunter of the giant camel. He probably stalked his prey to a water spring where he came to drink," said Le Tensorer.

"Ordinary camels appeared in the (Middle East) region some 6,000-7,000 years ago and, for the first time, we have a wild form and very, very old," he said.

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Mich. board OKs curriculum on evolution

LANSING, Mich. - The State Board of Education on Tuesday approved public school curriculum guidelines that support the teaching of evolution in science classes — but not intelligent design.

Intelligent design instruction could be left for other classes in Michigan schools, but it doesn't belong in science class, according to the unanimously adopted guidelines.

"The intent of the board needs to be very clear," said board member John Austin, an Ann Arbor Democrat. "Evolution is not under stress. It is not untested science."

Some science groups and the American Civil Liberties Union had worried that state standards would not be strong enough to prevent the discussion of intelligent design as the course expectations developed over the summer.

The guidelines approved Tuesday detail what the state expects school districts to teach in their science classes. If a district or teacher chose to include intelligent design in a science class, they could face a court challenge from opponents of teaching intelligent design.

Intelligent design's proponents hold that living organisms are so complex they must have been created by a higher force rather than evolving from more primitive forms.

Some want science teachers to teach that Darwin's theory of evolution is not a fact and has gaps.

Gregory Forbes, a community college biology instructor, said it appears the "doors have been shut" on those in Michigan who support the teaching of intelligent design as a viable scientific alternative to evolution.