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
I’m quite certain that humans have designed all manner of things. The question is, just what does that have to do with the issues at hand?
“What about professors in PUBLIC universities?”
I don’t care, but from a standpoint of usefulness in applied sciences it is still a waste of time. That is something the paying students would have to take up with their professors, administrators, what have you, as far as I’m concerned. The argument that I’m making now isn’t a moral argument, it is a practical argument about using time to impart knowledge that will best serve the student. ...As a moral argument, I had no choice but to go to public schools, until I was old enough to drop out. I didn’t get indoctrinated into the nuances of evolution, and I wouldn’t have bought it anyhow. As a college student taking classes in zoology, botany, chemistry and philosophy, I was inundated with evolution. I already had a broader education and understanding by then.
What do you think about the teaching of evolution in public universities?
And the dark skinned folks needed curly hair to go with their brown skin because??
How stupid can humans be??
RE: What do you think about the teaching of evolution in public universities?
WEll, if the course SPECIFICALLY SAYS : “Evolutionary Biology”, then I guess, the student has been specifically pre-informed what to expect.
I believe that one can teach BIOLOGY per se ( e.g. Cell biology, Molecular biology, etc.) without going to Darwinian evolution at all. It really isn’t necessary at all IMHO.
AND, they tend not to marry “white” people.
I don’t know the mechanism, but have you ever noticed how balck people have hardly any wrinkles?
You asked for peer-reviewed journals that prove intelligent design. I provided a link for you. And, what is more, provided a link to a product that is created by means of intelligent design.
Clearly, the field of "intelligent design" is more than just possible: it's real. But really, I suspect you're not opposed to that part of the debate at all, because of the following:
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.
You've conflated two very different subjects here. At the very least, it is no longer possible to claim that intelligent design is not "science," because it clearly is, in the case of human biotechnology. It is therefore demonstrably a valid scientific hypothesis -- one for which it is possible to provide examples where the hypothesis is correct. So in that, at least, you are wrong.
To demonstrate the validity of a hypothesis does not relieve the hypothesizer of the need to meet scientific norms, of course .... but you still must give up that part of your argument.
But I think that's really all beside the point, because what you really seem to be doing, is attempting to make a scientific case against the "supernatural;" but by your own claims that is almost by definition impossible.
And thus your attempt to tie your arguments to tie the supernatural, to other claims. The problem is, your attempt to make such an argument by reference to "intelligent design" is not valid.
You asked for peer-reviewed journals that prove intelligent design. I provided a link for you. And, what is more, provided a link to a product that is created by means of intelligent design.
Clearly, the field of "intelligent design" is more than just possible: it's real. But really, I suspect you're not opposed to that part of the debate at all, because of the following:
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.
You've conflated two very different subjects here. At the very least, it is no longer possible to claim that intelligent design is not "science," because it clearly is, in the case of human biotechnology. It is therefore demonstrably a valid scientific hypothesis -- one for which it is possible to provide examples where the hypothesis is correct. So in that, at least, you are wrong.
To demonstrate the validity of a hypothesis does not relieve the hypothesizer of the need to meet scientific norms, of course .... but you still must give up that part of your argument.
But I think that's really all beside the point, because what you really seem to be doing, is attempting to make a scientific case against the "supernatural;" but by your own claims that is almost by definition impossible.
And thus your attempt to tie your arguments to tie the supernatural, to other claims. The problem is, your attempt to make such an argument by reference to "intelligent design" is not valid.
Yes, I am sure.
Species or subspecies makes little difference to the reality that it is facile to argue that change within the population in response to the environment (evolution) was not at work over the last 3.5 million years.
Australopithocine was from 3 million years ago, while modern humans were not around until the last 100,000 years.
What happened to the Australopithocine?
The neo-Darwinian 'position':
In a universe of blind physical forces and genetic replication, some people are going to get hurt, other people are going to get lucky, and you won’t find any rhyme or reason in it, nor any justice. The universe we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil and no good, nothing but blind pitiless indifference.
– Richard Dawkins River Out of Eden: A Darwinian View of Life
I have argued that the discontinuous gap between humans and 'apes' that we erect in our minds is regrettable. I have also argued that, in any case, the present position of the hallowed gap is arbitrary, the result of evolutionary accident. If the contingencies of survival and extinction had been different, the gap would be in a different place. Ethical principles that are based upon accidental caprice should not be respected as if cast in stone.------------------------
- Dawkins
Parasitism and its Cost to Society. - Hundreds of families such as those described above exist to-day, spreading disease, immorality, and crime to all parts of this country. The cost to society of such families is very severe. Just as certain animals or plants become parasitic on other plants or animals, these families have become parasitic on society. They not only do harm to others by corrupting, stealing, or spreading disease, but they are actually protected and cared for by the state out of public money. Largely for them the poorhouse and the asylum exist. They take from society, but they give nothing in return. They are true parasites.The Remedy. - If such people were lower animals, we would probably kill them off to prevent them from spreading. Humanity will not allow this, but we do have the remedy of separating the sexes in asylums or other places and in various ways preventing intermarriage and the possibilities of perpetuating such a low and degenerate race. Remedies of this sort have been tried successfully in Europe and are now meeting with success in this country.
-Hunter’s Civic Biology:
Defend your position “apologist“…
Trying to teach biology without evolution is like trying to teach astronomy without gravity.
You can describe where things are and where they are going, but absent is the underlying explanation that makes it all make sense.
Fine, the Moon orbits the Earth and the Earth orbits the Sun; but how?
Fine, bacteria develop antibiotic resistance; but how?
“I believe that one can teach BIOLOGY per se ( e.g. Cell biology, Molecular biology, etc.) without going to Darwinian evolution at all. It really isn’t necessary at all IMHO.”
I agree. It serves no purpose in a practical sense, but as far as public universities go, it is unavoidable these days. That’s one reason why I think children should get their cultural and faith education from parents, ministers, or from whomever the parents choose. They need to be prepared for the assaults they will get from academia, media and associations they will experience.
“Trying to teach biology without evolution is like trying to teach astronomy without gravity.
You can describe where things are and where they are going, but absent is the underlying explanation that makes it all make sense.”
Then where are we “going” in evolution? Can you tell me, other than just somewhere “different?” We can predict precisely where Mars will be on any future date due to our understanding of gravity. It is convenient that a theory is never called to predict anything in the future since it’s rooted in randomness and is moving too slowly to “observe.” Evolution is however unhinged at so many points that it can be made to explain any past or present observation. I have read where it can even explain my wife’s shopping habits. Even the concept of “God” is an evolutionary construct to make the community more cohesive, hence more survivable. It explains everything, hence explains nothing.
But more importantly, when the integrity of the ‘genome’ is threatened - life fights back. Why? Is this by design?
Thus it explains antibiotic resistance, adaptation to the environment, how nylon eating bacteria arose, the high prevalence of sickle cell anemia where malaria is endemic, lactose tolerance into adulthood among cattle raising populations, how wolves were changed into dogs, and how speciation works (at the minimum between “kinds”).
Where are “we” going in evolution? Nowhere fast, as we are a very homologous species with worldwide distribution and reproductive isolation is unlikely.
But if you are attempting to make the argument that evolution is not a predictive science what do you predict will happen when I take a single bacteria, let it grow a bit, then plate it on ten different petri dishes and subject it to ten different stresses?
My prediction is that the petri dish subjected to heat stress will develop as a heat resistant strain of the bacteria, that the one subjected to cold will develop as a cold resistant bacteria, etc, etc.
I agree with your criticism as it applies to “evolutionary sociology” and any other attempts to explain anything humanistic cultural or theological via evolution. It explains everything to an equal degree, and thus really explains nothing.
Spare me the semantic gymnastics. You second point (and I’m flattered you’ve taken the work of the National Academy of Sciences as my own) is nothing more than an attempt to deflect from the reality of the Theory of Evolution. Are you attempting to imply that human management and utilization of technology somehow works to support the view that the range and complexity of biological systems are the product of intelligent design? If so, I’m afraid you’re failing.
RE: bacteria develop antibiotic resistance; but how?
By that, I am assuming how, without having to insist that it is via Darwinian mechanisms where there is a resultant GAIN in functional systems.
The mechanisms of mutation and natural selection aid bacteria populations in becoming resistant to antibiotics. However, mutation and natural selection also result in bacteria with defective proteins that have lost their normal functions.
Evolution requires a gain of functional systems for bacteria to evolve into man—functioning arms, eyeballs, and a brain, to name a few.
It can be thought of as :
1) An example of Darwinian evolution in action.
On the other hand,
2) It can also be thought of a NOT an example of evolution in action but rather variation within a bacterial kind.
My point is this -— WE DON’T HAVE TO INSIST on the answer on e way or the other as ESSENTIAL to understanding bacterial resistance.
In biology it is also called antagonistic pleotropy.
What do you mean “the integrity of the genome”?
The genome has functionality, it is not set it stone, but in fact it is INCAPABLE of being reproduced with 100% fidelity. Thus there is, over time, no “integrity” to the genome.
In the case of bacteria, they have a specific gene for an error prone DNA polymerase that they use to reproduce their genome during times of stress instead of the regular high fidelity DNA polymerase?
So if by “fight back” against environmental stress you mean “supercharge evolutionary change by expressing error prone DNA polymerase” then yes.
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