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16. A New Tool for Understanding Identity

Exciting New Vistas

DNA_Double_Helix

DNA base pairs (coloured bars) give rise to the totality of organisms from toadstools to brain surgeons (img 1)

Article #15 of this Series (GKIS) mentioned that science has opened exciting new vistas into our ancestral past and our identity through human genetics. In his book Shelter and Shadows, author Raymond Keogh says: “I turned to this emerging field to take the process further. The tenor of the entire investigation was changed by this shift in direction and placed the context of the story of my ancestors as a whole into a dimension I could not have imagined at the outset.”[1]

Professor F

To appreciate something of the power of human genetics in enabling us to comprehend our identity it is necessary to have a basic understanding of the subject. Perspectives in this relatively new discipline are changing rapidly as innovative techniques are being applied and as new information is being analysed, which means that current results must be accepted as part of a work-in-progress.

Discovery of DNA

In 1953, scientists Jim Watson and Francis Crick discovered DNA (deoxyribonucleic acid). This is a double helix of entwined crossbars, or base pairs and is the essential chemical code for any organism. Incredibly, the different patterns of bases give rise to the totality of organisms from toadstools to sequoias; from earth worms to brain surgeons.

800px-Francis_Crick

Francis Crick (2)

DNA can be thought of as a long word made up of chemical letters; these letters provide the written commands for the creation of the body’s chemicals and their resulting order. DNA is found mainly in the operating room of the cell: the nucleus. DNA does not do anything except send out commands to messenger molecules, which ensure that the various proteins or building blocks of our bodies are created in the right places and in just the right amounts. DNA is the fundamental code that makes us biologically who we are.

Male DNA

Fortunately for ancestral research, scientists have identified part of the male DNA (Y-chromosome) that remains the same for hundreds of generations. Therefore, if certain markers are identified for a man on this part of his DNA, then the same is automatically determined for his father and his father in turn and so on for thousands of years without change. Over the last decade genetic research has gradually defined the deep-rooted relationships between male DNA throughout the world and what emerges is a pattern that connects all men of our planet.

One of the co-discoverers of deoxyribonucleic acid (DNA) with Francis Crick. Between 1988-1992, Dr. Watson was associated with the National Institutes of Health helping to establish the Human Genome Project.

Jim Watson (3)

Tiny and more rapid mutations also occur at random on other parts of the Y-chromosome and these steadily accumulate as specific molecular markers. The changes are then passed down through the generations and allow us to refine our links into our biological past. Through the combination of stable and more rapid marker mutations we have a mechanism to help us advance, in an unprecedented way, the story of male human genealogy.

Female DNA

To follow the female line we need a different foundation. Tiny bodies called mitochondria are found in each of our cells. They function like batteries within the cellular fluid and are the powerhouses of the cells. The DNA of the mitochondria is not part of the cell’s control nucleus. It arises exclusively from our mothers. However, as with the Y-chromosome, parts of the mitochondrial DNA are very stable and remain the same for hundreds of generations while other parts exhibit more rapid changes.

Autosomal DNA

Autosomal DNA refers to the non sex-determining chromosomes in our genetic makeup that have emerged from the wider human genome and which we have inherited from our ancestors on all sides, both male and female. The mutations on our Y-chromosomes, mitochondria and our autosomal DNA are patterns that allow each of us to reconstruct a genetic family tree, which is written in our bodily chemistry. Not only can we construct the tree itself; the resulting mutations tend to be found in varying frequencies across the surface of the earth and we can determine approximately where and when they occurred. Through this process it is possible to trace the collective migrations of modern humans around the globe from our beginnings in Africa. Although still in its infancy, genetics has provided the best insight into the story of human development and is forcing the rewriting of history and pre-history.

Key to Identity

This is a highly simplified outline of the scientific base that allows each of us to reconstruct our ancestral past. What is different about the present approachin comparison to most other studies on identityis that our unchanging DNA sequences become the foundation for determining the deep-seated physical identity of the individual. In other words, the unchanging nature of our DNA sequences opens up the possibility, for the first time, of drawing up an objective definition of personal identity. Moreover, the identity of the community from which the individual emerges can also be defined objectively on the basis of human genetics.

Refs

[1] Keogh, R. M. Shelter and Shadows. (To be published in September 2016 as part of The Gerald Keogh Identity Series). here

Image acknowledgements: Wikicommons: img (1) National Human Genome Research Institute; (2) Francis Crick.png: photo: Marc Lieberman (3) James Dewey Watson: National Cancer Institute

GKIS Gerald Keogh Identity Series

Next: Objective Definitions of Identity here