How did the documentary on the genetic odyssey come about?
Spencer Wells, the principal author, was invited to make a documentary of these remarkable findings. The ‘Journey of Man’ — shot in various locations in a year’s time — was a monumental story. When it aired on television in 2003, it created ripples among scientists and commoners alike.
The Madurai episode was the key. Following this success, Dr. Wells convinced the National Geographic that further research with public participation was necessary. In 2005, the Genographic Project was launched.
Do various populations contribute genetic samples for this research?
Ten different laboratories around the world will collect 10,000 DNA samples each, creating a virtual museum of human history in the process! Apart from this, 216,000 people have purchased the cheek-swab kit from National Geographic worldwide, learnt their migratory pathways, and celebrated their ‘heritage.’
In India, we select distinct populations, known to anthropologists, based on socio-cultural characteristics, language families, domicile and isolation — how far they are segregated from others in terms of marriage etc. (The initial Madurai study involved Kallars, Saurashtrians and Yadhavas.)
Briefly explain the science behind the project.
In the 3-billion-base-pair-long human DNA sequence, simple mutations (called SNPs or VNTRs) are possible during replication.
Nucleotides are accidentally replaced once in a while — mostly copying errors — and these ‘mistakes’ are inherited from that generation onwards.
These variants can serve as genetic markers to trace migration or ancestry.
Why is the Y chromosome, present only in men, chosen to study markers?
A segment of the Y chromosome (NRY) does not recombine, and the mutations, which accumulate over time, are passed on without ‘shuffling’ from father to son. Hence these markers, inherited through male lineages, are used to follow migratory splits of Man over time.
Does the DNA of women carry the migration tale as well?
Both males and females inherit mitochondrial DNA (mtDNA) from their mothers. As the mitochondria of sperms does not enter the egg during fertilization, studying mtDNA helps trace the mother’s route of migration.
What is the larger significance of this research effort?
The awareness ‘Mankind is the same’ is valuable for any nation to live in peace and harmony.
Migratory pathways, as determined by DNA, also correlate to the cultural evolution of a society.
DNA studies on fossils, complemented by archaeological excavations could answer intriguing questions such as: Who were the Harappans? Did the Dravidian and Indo-European languages originate in India or arrive here?
The broad outline of the genetic epic is clear — finer details will now emerge.
http://www.hindu.com/seta/2007/08/23/stories/2007082350011500.htm