Tuesday, March 3, 2009

The Evolution Of Race: Homo Erectus?

The 2002 discovery of a Homo erectus fossil found in a marble quarry in Denizli, Turkey was a 20 to 40-year-old dark skinned male with signs of tuberculosis, according to Hurriyet news.

"The 500,000 years old skull fossil is expected to provide hints to the science world on the first humans’ migration and spreading on earth. The fossil agrees with the thesis of mankind originating from Africa", said Mehmet Cihat Alçiçek, assistant professor at the Geological Engineering Faculty in Pamukkale University.

It is documented that as modern humans moved north or south from the equator, their skin color becomes lighter. The further north or south from the equator, production of melanin (skin pigment) in the body decreases gradually so that enough vitamin D can be absorbed from sunlight. This Homo erectus fossil was a dark-skinned male, presumably had migrated out of Africa to Turkey. He had suffered from tuberculosis, a disease susceptible from vitamin D deficiency. Though nothing conclusive can be said about his diet, we can infer that his dark skin was not adaptive to his new environment. His body was simply not absorbing enough vitamin D from sunlight.

What I find particularly interesting from this news article is a snippet of natural selection 500,000 years ago. Depending on where you live geographically, there are selective pressures that select for lighter or darker skin color. Individuals with lighter skin color are better adapted to live further away from the equator while individuals that live close to the equator are better adapted with darker skin tone. This leads me to my question, did the evolution of skin color started in Homo erectus?

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