In high doses, ultraviolet light can damage skin and DNA molecules, but the body does need some UV light to help us produce vitamin D. Our bodies use melanin to regulate how much UV light our skin lets in.

Courtesy George Chaplin

Ultraviolet Light And Pregnancy

Because women build babies in their wombs, they need more vitamin D to produce extra calcium for the baby’s bones. Could that explain this difference: When scientists look at the underarm skin of men and women in every color group of humans, the women on average are always lighter than the men. Are the ladies lighter to produce a little extra Vitamin D for the babies?

• Listen: Dr. Nina Jablonski describes the “Under Arm” test.

To begin, please point your elbow to the ceiling.

Then imagine yourself naked.

Then look at the patch of skin on the inside of your upper arm, the part of you that almost never sees the sun.

Whatever color you see there is what experts call your basic skin color, according to professor Nina Jablonski, head of the Penn State Department of Anthropology.

And that color, the one you have now, says Jablonski, is very probably not the color your ancient ancestors had — even if you think your family has been the same color for a long, long time.

Different Place, Different Color

Skin has changed color in human lineages much faster than scientists had previously supposed, even without intermarriage, Jablonski says. Recent developments in comparative genomics allow scientists to sample the DNA in modern humans.

By creating genetic “clocks,” scientists can make fairly careful guesses about when particular groups became the color they are today. And with the help of paleontologists and anthropologists, scientists can go further: They can wind the clock back and see what colors these populations were going back tens of thousands of years, says Jablonski.

She says that for many families on the planet, if we look back only 100 or 200 generations (that’s as few as 2,500 years), “almost all of us were in a different place and we had a different color.”

Over the last 50,000 years, populations have gone from dark pigmented to lighter skin, and people have also gone the other way, from light skin back to darker skin, she says.

“People living now in southern parts of India [and Sri Lanka] are extremely darkly pigmented,” Jablonski says. But their great, great ancestors lived much farther north, and when they migrated south, their pigmentation redarkened.

“There has probably been a redarkening of several groups of humans.”

Why We Change Color

The repigmenting process is increasingly well understood.

“Humans started in Africa,” Jablonski says, the part of Africa near the equator where it is intensely sunny with lots of ultraviolet light.

Ultraviolet light, or UV, in high doses can age the skin and damage the DNA molecule, which makes it harder to build a fetus. Not to mention that ultraviolet light can sometimes cause skin cancer.

On the other hand, if a human is plopped down in, say, Norway, where the days can be short and there is precious little ultraviolet light, this creates problems, too. All vertebrate animals need ultraviolet light to help produce vitamin D. Vitamin D helps us absorb calcium from our food to build strong bones. If we don’t get enough ultraviolet light, we’re less likely to survive to reproductive age to produce strong-boned babies.

Thus the dilemma: People who live in sunny climes around the equator have too much UV. People who move away from the equator eventually have too little UV.

Hooray For Melanin

The solution is what Jablonski calls “a really cool molecule”: melanin. In different concentrations, melanin makes skin lighter or darker. Kind of like a Venetian blind, it can let UV light in or keep it out.

Melanin has evolved in many different animals. Humans have had it for a long, long time and what Jablonski and others have learned is that when early humans migrated from the equator, their melanin levels changed.

That doesn’t mean they lost their tans. It means they had very specific genetic changes that allowed them to live and successfully reproduce in less sunny places. Darwin teaches that these changes began randomly. Somebody in the population at some point had a baby, and that baby, just by chance, had a little change in its DNA that made her skin, for example, a little lighter. When that baby moved north to Europe, lighter skin gave her an advantage as a grown-up, because it helped her produce strong-boned babies who could survive and have babies of their own.

Successive mutations created successive generations of lighter and lighter people as they moved north.

“This, in short, really created the gradation of skin color that we see in modern humans today,” says Jablonski. Her map of UV radiation levels on Earth closely mirrors the array of skin colors on Earth.

Skin Color Is A Fleeting Thing

The big surprise is how fast these changes can occur.

“Our original estimates were that [skin color changes] occurred perhaps at a more stately pace,” Jablonski says. But now they’re finding that a population can be one color (light or dark) and 100 generations later — with no intermarriage — be a very different color.

Figuring 25 years per generation (which is generous, since early humans walked naked through the world — clothes slow down the rate), that’s an astonishingly short interval.

It’s “a blink of an eye,” she says.

Audio & More available at NPR (Click Below)

Your Family May Once Have Been A Different Color : NPR.

For as little as $400 a year Harlem Academy offers city kids a very intense education.

Hands on: Vincent Dotoli started his school with one classroom and 12 first graders.

Zina Mingo has lived in Harlem for all her 40 years and now teaches in a Harlem public school. But committed as she is to the community, she wasn’t willing to subject her son, Devon, now 8, to the educational system she works for. “Most of the schools in Harlem are failing schools, and that’s just not an option to me,” she says.

Instead, Mingo is pinning her hopes for Devon on Harlem Academy, a four-year-old not-for-profit school just north of Central Park. With its small classes, focus on rigorous academics, required parental involvement and long school day, the school gets results; 90% of third graders score above the national median in reading and math. Students arrive at 7:30, begin sports at 3:45 and leave at 5 or 6, depending on whether they want homework help after sports. For that, parents pay as little as $400 a year and as much as $16,000, depending on income.

Harlem Academy is the passion of headmaster Vincent Dotoli, 39, whose lawyer father and cpa mother could afford to buy him a private school education at Far Hills Country Day in New Jersey. After college he taught in rural Maine and Rhode Island and then for four years at Buckingham Browne & Nichols, a well-endowed 125-year-old private school in Cambridge, Mass. But he didn’t feel his efforts there made much of a difference. “Those students were going to be successful whether I was there or not,” he says.

So in 2001 Dotoli enrolled at Columbia University to earn a master’s in education administration. His thesis was on a model for a private urban school that could skirt the public school bureaucracy dragging down big city schools, while involving parents, who are too often treated as a nuisance in those same schools. Edmund W. Gordon, director of Columbia’s Institute for Urban & Minority Education, joined Dotoli in meeting with prospective students and parents. Harlem Academy opened in September 2004 with 12 first graders in one room rented from an arts group. In 2005 it moved to bigger quarters and now has 74 first-through-fifth graders.

Country Day In Harlem – Forbes.com.

President Obama’s election, and this year’s 100th anniversary of the NAACP, means there has probably never been more reason to celebrate the annual February observance, historians say.

“Barack Obama is opening our hearts and minds to the true meaning of Black History Month,” Barron said. “African Americans won’t be viewed as just a minority but as people who make a difference.”

Obama’s election, and this year’s 100th anniversary of the NAACP, means there has probably never been more reason to celebrate the annual February observance, black leaders and historians say.

“We celebrate whenever a glass ceiling is broken and the presidency may be the highest glass ceiling,” said Benjamin Todd Jealous, president and CEO of the NAACP, which is celebrating its 1909 founding this year.

But those leaders also agree those milestones don’t mean that racial inequalities no longer exist. While Obama’s breaking of the color barrier in the White House may make the NAACP’s job easier, Jealous said they will pressure Obama just as they have past presidents.

Gerald Early, a professor of African American Studies at Washington University in St. Louis, said that Obama’s election should not be viewed as the end of racism, but “should be taught as an event that signaled a new era in American race relations.”

“With Obama as president, I think people are more optimistic about race relations than they’ve been in a long time,” he said.

This optimism is seen in Black History Month celebrations planned throughout this month in the 1,700 local NAACP units and hundreds of primary, secondary and university campuses nationwide.

This year’s Black History Month theme is “The Quest for Citizenship in the Americas,” determined by the Association for the Study of African American Life and History, said Daryl Scott, vice president for programs.

Stephanie Smith Budhai, 23, head of the University of Maryland’s Black History Month Committee, said the theme correlates well with Obama’s presidency.

“Barack Obama shows that (African Americans’) citizenship is just as important as the citizenship of any other ethnicity or race,” she said.

Black History Month has added meaning in 2009 – USATODAY.com.

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