In what has been aptly described as the greatest speech of the 20th century, Dr. Martin Luther King Jr. said in part, "I have a dream that one day on the red hills of Georgia the sons of former slaves and the sons of former slave owners will be able to sit down together at a table of brotherhood." Dr. King was cruelly cut down by an assassin's bullet too soon to learn that science would give great weight to his stirring vision.
Within our cells are tiny organelles called mitochondria. They reproduce asexually, one indication of a possible origin as free living bacteria. Mitochondria are passed on to human children by the mother. Geneticists have analyzed that mtDNA use techniques that compare and contrast similarities in the individual letters of the genetic code. This molecular clock is one method to gauge how closely or distantly we are each related to one another. And it turns out that all humans alive today can trace their mitochondrial ancestry back to a single female who lived about 150,000 years ago. She's been dubbed Mitochondrial Eve.
MT Eve is not the only female ancestor shared by all humans. She's our most recent common ancestor exclusively via matrilineal descent. You have the DNA of your father's mother in your nuclear genome -- it's a fair bet we picked up an allele here or a sequence there from archaic hominid populations living around the same time -- but mitochondrial DNA comes from the female line, ultimately converging on Eve. Fossil evidence independently supports the idea that anatomically modern humans come from a small band of people that evolved near Kenya about 160,000 - 200,000 years ago.
February is Black History month. We honor the contributions of African-Americans and reflect honestly on the challenges many still face in fully securing the rights and privileges that others take for granted. But black history could also be accurately cast as Human History. Because biology reveals that we descend from such a small clan in the geologically recent past, the 'sons of former slaves and the sons of former slave owners' are brothers. The emerging scientific consensus is that each and every one of us belongs to a single African family, surname H. sapiens.
As a family, we have yet to reach the promised land of complete social equality that Dr. King envisioned. It is regrettable to say the least that some of our siblings still happily stoke the fires of prejudice for even a glimmer of political profit. But other family members have made great strides toward creating a just society, where our children are judged 'not by the color of their skin, but by the content of their character'. Here's to hoping we swiftly finish making one African's Dream a reality for all.
Saturday, February 17, 2007
February is Black History Month
Worthy of reminder until we get it right. I corrected a couple of misspellings but only wish I could write this well: