Genealogical records are currently the system of choice for people tracing their family history. But in the next decade, we will be able to identify many of our relatives by searching a DNA database of personal genome sequences. There are good reasons for switching to DNA: in general, historical records cover at most the past 500 years; our genomes, in contrast, bear the stamp of tens, if not hundreds of thousands of years of history. Even individuals without genealogical records will be able to correctly create a family tree with connections to known relatives, to those they were unaware of, and to relatives so distant that they stretch the meaning of the word ‘family’.In fact, DNA and traditional genealogy complement one another. The competent researcher will not "switch" to DNA, but will use all available resources to reconstruct relationships. Paper records offer an imperfect and temporally-restricted window into one's ancestry, but DNA has its own weaknesses: "Within historical times, you have ancestors from whom you have no DNA". Genetic material, not being infinitely divisible, is necessarily transmitted in discrete blocks, rendering it impossible even in theory to reconstruct complete pedigrees from an individual's DNA. In practice, even where DNA is transmitted, its informativeness will have limits.
The practical limits of DNA pedigree reconstruction remain to be determined, but even if it proves possible to go back, say, ten generations or more in fairly complete fashion using only DNA of living individuals, such skeletal outlines would prove rather lifeless without names, dates, locations, and historical context.
Of course, on questions of genetic affinity among the living, full genome sequences will ultimately decide.
But speculating about how genotyping or sequencing data will affect genealogy is not really the point of the article. The purpose is, in the words of some Nature editor, to argue that "[o]ur notions of family, population and race may need revising in the age of personal genomics".
Only skin deepOh, that's the dominant strain of anthropological thought the Boasians have been pushing. I'd thougt they were 100% agreed with Mr. Desi that race is purely a "social construct". And I'm pretty sure it's new genetic data Chakravarti is trying to run damage control on: that is, in the face of genomic data that proves traditional racial classifications are meaningful, scientists must continue to maintain something along the lines of "science proves race doesn't exist". That's the sort of "revising" Chakravarti wants to do.
Perhaps the most striking consequence of more and more people having their entire genome examined for genetic variation is the blurring of our concept of discrete human populations. Current thinking, championed by anthropologists and buttressed by old genetic data, is that human populations are intact groups that have had their own language and culture for eons.
Currently, the population view dominates in genetics because researchers sample clusters of individuals from distantly related groups. The clearly observable, or measurable, physical and genetic differences between people are especially marked when people from the peripheries of the spectrum of human variation are compared — so, for example, when Africans are compared with Europeans or Asians.Chakravarti tries to imply that natural selection has caused populations to diverge only in genes affecting physical appearance. The actual evidence points elsewhere. See The 10,000 Year Explosion.
Race has long been a socio-political construct. But by focusing on the effects of natural selection on genes whose effects are visible, and sampling people from the extremes of human diversity, geneticists have unwittingly (and sometimes wittingly) added credence to society’s views on separateness by genetically characterizing racial categories.
However, the current picture emerging from genetic studies is that we are all multiracial, related to each other only to a greater or lesser extent. More detailed data on genetic variation, along with an improved sampling of humanity, are showing continuity in variation across the globe, not abrupt transitions between population-specific sequence patterns. Differential population growth, about 10,000 years ago, based on the evolution of agriculture, technology and politics seems to have made sparse isolates of our species into the ‘major’ groups of today. In other words, except for immigrants, kinship between two humans seems to be directly related to the geographical distance between their birthplaces."Peripheral" "sparse isolates" numerically dominating intermediate populations tends to undermine the "clines means race doesn't exist" argument.
An even clearer, and unbiased, picture of humanity’s genetic diversity and relationships would emerge if geneticists focused on individuals instead of populations. This may involve sampling humans randomly across a grid, and then assessing their individual and group features (such as birth place, parental birth places, language and group affiliations). Genome-wide studies carried out in this way could result in individual identity and kinship coming to define populations rather than the other way around. We could test once and for all whether genetic race is a credible concept.Not a bad idea. Data is good. The more surveys of this sort, the better. Not that I would expect any imaginable result of a study of this sort to affect the substance of the pronouncements of the Chakravartis of the world. This is why:
This would be tremendously exciting. It is bound to stir up our deeply held notions of who we are, where we came from, our history and thus our politics. More often than not, the views of society have shaped science rather than the other way around. In this instance, it may be time for science to reshape the views of society. By dismantling our notions of race and population, we may better appreciate our common, shared and recent history, and perhaps more importantly, our shared future. Overhauling such concepts in the light of genetic research is particularly important if we are to accommodate the changing face of human groups around the world thanks to increased immigration to distant lands. Such migration has happened before, as our genomes show, only slowly, over 150,000 years.I'm sure I don't need to spell out for you the irony in the above paragraph.
 Aravinda Chakravarti. Being Human: Kinship: Race relations. Nature 457, 380-381 (22 January 2009) | doi:10.1038/457380a; Published online 21 January 2009