James' World 2

Click the link below the picture

.

Imagine a world where everyone had brown skin. Tens of thousands of years ago, that was the case, say scientists at Pennsylvania State University. So, how did white people get here? The answer lies in that tricky component of evolution known as a genetic mutation.

Out of Africa

Scientists have long known that Africa is the cradle of human civilization. There, our ancestors shed most of their body hair around 2 million years ago, and their dark skin protected them from skin cancer and other harmful effects of UV radiation. When humans began leaving Africa 20,000 to 50,000 years ago, a skin-whitening mutation appeared randomly in a sole individual, according to a 2005 Penn State study.1 That mutation proved advantageous as humans moved into Europe. Why? Because it allowed the migrants increased access to vitamin D, which is crucial to absorbing calcium and keeping bones strong.

“Sun intensity is great enough in equatorial regions that the vitamin can still be made in dark-skinned people despite the ultraviolet shielding effects of melanin,” explains Rick Weiss of The Washington Post, which reported on the

findings. But in the north, where sunlight is less intense and more clothing must be worn to combat the cold, melanin’s ultraviolet shielding could have been a liability.

Just a Color

This makes sense, but did scientists identify a bonafide race gene as well? Hardly. As the Post notes, the scientific community maintains that “race is a vaguely defined biological, social, and political concept…and skin color is only part of what race is—and is not.”

Researchers still say that race is more of a social construct than a scientific one because people of purportedly the same race can have as many differences in their DNA as people of separate so-called races do. It’s also difficult for scientists to determine where one race ends and another begins, considering that people of supposedly different races may have overlapping features in terms of hair color and texture, skin color, facial features, and other characteristics.

.

.

.

Click the link below for the article:

.

__________________________________________