Posted on 02/28/2011 12:05:32 PM PST by SeekAndFind
Variations in skin color provide one of the best examples of evolution by natural selection acting on the human body and should be used to teach evolution in schools, according to a Penn State anthropologist.
"There is an inherent level of interest in skin color and for teachers, that is a great bonus -- kids want to know," said Nina Jablonski, professor and head, Department of Anthropology, Penn State. "The mechanism of evolution can be completely understood from skin color."
Scientists have understood for years that evolutionary selection of skin pigmentation was caused by the sun. As human ancestors gradually lost their pelts to allow evaporative cooling through sweating, their naked skin was directly exposed to sunlight. In the tropics, natural selection created darkly pigmented individuals to protect against the sun.
Ultraviolet B radiation produces vitamin D in human skin, but can destroy folate. Folate is important for the rapid growth of cells, especially during pregnancy, when its deficiency can cause neural tube defects. Destruction of folate and deficiencies in vitamin D are evolutionary factors because folate-deficient mothers produce fewer children who survive, and vitamin D-deficient women are less fertile than healthy women.
Dark skin pigmentation in the tropics protects people from folate destruction, allowing normal reproduction. However, because levels of ultraviolet B are high year round, the body can still produce sufficient vitamin D. As humans moved out of Africa, they moved into the subtropics and eventually inhabited areas up to the Arctic Circle. North or south of 46 degrees latitude -- Canada, Russia, Scandinavia, Western Europe and Mongolia -- dark-skinned people could not produce enough vitamin D, while lighter-skinned people could and thrived. Natural selection of light skin occurred.
The differences between light-skinned and dark-skinned people are more interesting than studying changes in the wing color of moths or, the most commonly used evolutionary example, bacterial colonies, according to Jablonski. Adaptation to the environment through evolutionary change becomes even more interesting when looking at the mechanism of tanning.
"In the middle latitudes tanning evolved multiple times as a mechanism to partly protect humans from harmful effect of the sun," Jablonski told attendees at the annual meeting of the American Association for the Advancement of Science today (Feb. 20) in Washington, D.C.
Tanning evolved for humans so that when ultraviolet B radiation increases in early spring, the skin gradually darkens. As the sun becomes stronger, the tan deepens. During the winter, as ultraviolet B wanes, so does the tan, allowing appropriate protection against folate destruction but sufficient vitamin D production. Tanning evolved in North Africa, South America, the Mediterranean and most of China.
Natural variation in skin color due to natural selection can be seen in nearly every classroom in the U.S. because humans now move around the globe far faster than evolution can adjust for the sun. The idea that variation in skin color is due to where someone's ancestors originated and how strong the sun was in those locations is inherently interesting, Jablonski noted.
"People are really socially aware of skin color, intensely self-conscious about it," she said. "The nice thing about skin color is that we can teach the principles of evolution using an example on our own bodies and relieve a lot of social stress about personal skin color at the same time."
Jablonski noted that the ability to tan developed in a wide variety of peoples and while the outcome, tanablity, is the same, the underlying genetic mechanisms are not necessarily identical. She also noted that depigmentated skin also developed at least three times through different genetic mechanisms. Students who never tan, will also understand why they do not and that they never will.
Provided by Pennsylvania State University
Adaptation, not evolution. We are all still humans and will always all still be humans.
So you don’t believe all humans share common ancestry then.
In as much as those who don’t understand evolution attribute to it racism, at least it never denied the OBVIOUS common descent of all human beings.
We are all cousins from the same family. The evidence of this is unmistakable.
The idea of “multiple Adams” or that Adam was only the father of the Jewish people has a long and storied history, all of it racist crackpot and delusional.
What did YOU think the garden of Eden story was about??
It’s more than just vitamin d and sunlight I believe. One of the tidbits of trivia I’ve picked up in this lifetime is that during the Korean war, soldiers of African descent acquired frostbite injuries at a rate 4 times higher than soldiers of European descent.
Stopped right there! Probably has a "trick" to "hide this- or-that" Just like that Mann guy up at Penn who's tree ring BS was heavily supplemented with BU!!SH!T.....
If you think about it. If it isn't a formulaic provable function and you rely on samples from different places, he who controls what samples from where controls the outcome.
OK, so Glowball Warming causes skin to darken...is that the gist of this..../sarc
So Al Gore is against Glowball Warming = Al Gore is a Racist
From the 2010 Encyclopedia of Life Sciences, in an article by researchers at UC Davis and the University of Michigan, comes further confirmation that "pseudogenes," a pillar of the argument against design, display multiple functions after all, notably in gene regulation. In the journal Synthese, a University of British Columbia philosopher demonstrates the limits, in principle, facing schemes of evolutionary self-organization. In Complexity, another peer-reviewed paper takes aim at gene duplication as the supposed royal road to generating new genetic functionality, citing insecticide resistance in blowflies among other illustrations. In Floriculture and Ornamental Biotechnology, a biologist at Germany's Planck Institute for Plant Breeding Research focuses on a particular feature of some flowering planets as demonstrating, in Michael Behe's terms (cited explicitly along with other ID advocates), evidence that would make it virtually impossible to account for by Darwinian stepwise evolution. Another peer-reviewed paper by Dembski and Marks in the Journal of Advanced Computational Intelligence and Intelligent Informatics joins the list of such publications coming out of the Evolutionary Informatics Lab. From the same source, led by computer scientists at Baylor University, comes a peer-reviewed journal article in BIO-Complexity, debunking a computer program supposed to simulate unguided evolution and widely hailed by Darwin apologists like Kenneth Miller. Finally, a paper in the International Journal of Design & Nature and Ecodynamics offers evidence that we live in an "engineered world."
How do you know how th Creator created? If you believe in the God of the Bible, he specifically states that after the 6 days of Creation, the seventh day of worship, that “there was not a man to till the ground”. It is neither racist, crackpot or delusional. Of course we are all children of our Father, and as such we are “cousins”, but each and every race was created and God said it was good. None superior, none inferior, but different strengths and weaknesses. You are as free as I to believe what you do. Go your own way and be happy, but don’t call me or my belief racist. By labeling my thoughts as wrong and racist, you are specifically saying that your beliefs are correct and not racist.
Ha!Ha!Ha!Ha! No! Stop! You’re killing me! Oh! Let me catch my breath! Ha!Ha!Ha!Ha! Really! Where do they find these people? Ha!Ha!Ha!Ha!
Skin color related to EVOLUTION? Talk about POLITICALLY INCORRECT!!
In 1999, the NAS released a second version of Science and Creationism, again reassuring the public that “science and religion occupy two separate realms
Fearing the public’s unyielding skepticism of evolution, the NAS issued another ex cathedra edict in 2008 promoting misinformation about intelligent design (ID) and bluffs about the scientific status of Darwinian evolution, stating “Evolutionary biology has been and continues to be a cornerstone of modern science.”
So, to cite a peer-reviewed journal that would satisfy you would obviously be almost impossible.
However, I'll provide one, and provide a two, simple, irrefutable facts that even an evolutionist should be able to understand.
1) There is less than 1 chance in 10^282 (one in one million trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion) that life exists on even one life-support body anywhere in the universe without invoking divine miracles. There are a maximum of only ≈ 10^22 life support bodies in universe {Reference: Fine-Tuning of Physical Life Support Body by Hugh Ross (Pasadena, CA: Reasons To Believe, 2002}
2) NASA hired Yale University’s Harold Morowitz to study the complexity of a protein molecule. Dr. Morowitz concluded that the probability of life occurring by chance is 1:10^236, which takes into account all the atoms in the universe, and the chance that the right ones came together just once to form a protein molecule. He adds that once you get to 1:10^15, the probability of an event ever happening is negligible. He said “The universe would have to be trillions of years older, and trillions of times larger, for a protein molecule to have occurred by random chance.”
3) It's called angularity - the fact that the angular diameters of the moon and sun as viewed from Earth are almost exactly the same (less than 0.05 degrees), though the two objects differ greatly in size and distance from Earth. Without that coincidence, we would never experience the awesome total eclipses of the sun and moon. No other known sun/planet/moon angularity is even close!
I know neither this nor any amount of factual data will convince you (one's religion is nearly impossible to change), but it may provide insight to those who are teachable and will provide assurance to those who know the Designer.
Hmmm...3.5 million years of natural selection in isolation and no new species of genus homo, just variations of skin color and complete interbreeding capacity. Wonder why.
.... oh, dear. This will not sit well with the “no genetic basis for race” crowd....
RE: Skin color related to EVOLUTION? Talk about POLITICALLY INCORRECT!!
Actually they don’t DARE ask the next obvious question (that is, if you believe in evolution’s survival of the fittest ) — How is skin color related to the LEVEL of evolution? Is the darkness or lightness of one’s skin correlated with one’s being more highly evolved?
Darwin dared to answer that during his time when political correctness was non-existent. Today, if you so much as MUSED about it allowed, you’ll be the victim of a sustained verbal and academic assault which will all but enusre the end of your career ( SEE: Summers, Lawrence, as an example ).
“No sir. You are stuck on the idea that evolution is moving a species towards some destination. No such thing. Any individual is either more or less fit to survive compared to any other individual. The word progress simply does not apply.”
If survival is the key, why would single-cellular organisms, with their rapid reproduction from generation to generation, ever evlove into something more complicated? What advantage does a human have over bacteria when it comes to survival in different environments? What environmental pressure would ever result in a multi-cellular organism having advantage over single cellular organisms? What mutation would cause a single cell organism to have an advantage as it evolves into a multi cell organism. What mutation, or series of mutations, would even result in a single cell organism to become multi cell regardless of selective advantage. Looks like evolution would push us all to rapidly reproducing simple organisms.
It's an example of an amusing argument, though .... the explanation supplied for some particular evolutionary mechanism -- in this case, for the evolution of dark (or light) skin -- almost invariably relies on some ex post facto application of a human design. It's that old fallacy, post hoc, ergo propter hoc, dressed up in a fancy lab coat.
Even if we grant that evolution somehow explains it, the truth is almost certain to be much more complicated.
A different example that shows the danger: it's been observed that domesticated animals often have coats with large spots. And it turns out that there is some evidence that these spots are in some way correlated to selective breeding. But the correlation turns out to be for selective breeding for docility, not coat patterns.
So, sure, one could come up with a dandy explanation for why skin is dark.... but the spotted cow suggests that there's probably a different explanation than the easy, human-designed one.
Here's one: Journal of Biotechnology.
Oh, and here's an actual commercial product that shows that intelligent design is not only "proved," but marketable.
3.5 million years and no new species of homo? Say what?
How about Homo Neanderthal?
LOL! Your third rate source doesn’t reflect reality; you done nothing but present apologetics or misapplication of findings.
"The claim that equity demands balanced treatment of evolutionary theory and special creation in science classrooms reflects a misunderstanding of what science is and how it is conducted. Scientific investigators seek to understand natural phenomena by observation and experimentation. Scientific interpretations of facts and the explanations that account for them therefore must be testable by observation and experimentation.
Creationism, intelligent design, and other claims of supernatural intervention in the origin of life or of species are not science because they are not testable by the methods of science. These claims subordinate observed data to statements based on authority, revelation, or religious belief. Documentation offered in support of these claims is typically limited to the special publications of their advocates. These publications do not offer hypotheses subject to change in light of new data, new interpretations, or demonstration of error. This contrasts with science, where any hypothesis or theory always remains subject to the possibility of rejection or modification in the light of new knowledge."
Your appeal to authority (evidenced by writing out really big numbers) is completely unsupportable, and you completely miss Morowitz's point - the assembly of chemicals is anything but random - I suggest you look into valence and electro-neutrality.
Finally, an eclipse? Really? That proves the existence of god? Wow - you standards must be lower than I thought...
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