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.

The report says children’s lives are “more difficult than in the past”

The aggressive pursuit of personal success by adults is now the greatest threat to British children, a major independent report on childhood says.

It calls for a sea-change in social attitudes and policies to counter the damage done to children by society.

Family break-up, unprincipled advertising, too much competition in education and income inequality are mentioned as big contributing factors.

A panel of independent experts carried out the study over three years.

The report, called The Good Childhood Inquiry and commissioned by the Children’s Society, concludes that children’s lives in Britain have become “more difficult than in the past”, adding that “more young people are anxious and troubled”.

According to the panel, “excessive individualism” is to blame for many of the problems children face and needs to be replaced by a value system where people seek satisfaction more from helping others rather than pursuing private advantage.

A spokesman for the Department for Children Schools and Families said: “We know there are still risks and challenges ahead for children and parents and that there is more for us all to do”.

‘Tone deaf’

The inquiry has a long list of recommendations including:

• abolishing Sats tests and league tables in English schools

• a ban on all advertising aimed at the under 12s and no TV commercials for alcohol or unhealthy food before the 9pm watershed

• stopping building on any open space where children play

• a high-quality youth centre for every 5,000 young people

“Individual freedom and self-determination bring many blessings,” writes the report’s principal author, Labour peer Lord Richard Layard.

“But in Britain… the balance has tilted too far,” he says.

Another contributor, the Archbishop of Canterbury Rowan Williams, suggests society has become “tone-deaf to the real requirements of children… in a climate where the mixture of sentimentalism and panic makes discussion of children’s issues so difficult”.

The panel, made up of 11 experts including eight university professors, says its conclusions are evidence based.

But some of its findings on family life in Britain are bound to be controversial.

Working mothers

It cites research suggesting that three times as many three year olds living with lone parents or a step-parent have behavioural problems compared with those living with married parents.

Children with separate, single or step parents are 50% more likely to fail at school, have low esteem, be unpopular with other children and have behavioural difficulties, anxiety or depression,” it argues.

“Child-rearing is one of the most challenging tasks in life and ideally it requires two people,” the report concludes.

It also suggests that having many more working mothers has contributed to the damage done to children.

MORE…

BBC NEWS | UK | Education | Selfish adults ‘damage childhood’.

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.

As technology evolved over the past few decades, power has passed from the hands of the creators or delivery channels of information to its users — you. (AFP/Getty Images)

Media Is Changing, But Some Things Endure, Jeff Greenfield On The Evolution Of The Media, And How Some Timeless Qualities Withstand Change – CBS News.