Washington, Feb 21 : Scientists have produced the largest and most detailed worldwide study of human genetic variation, which would offer new insights into early migrations out of Africa and across the globe.
Carried out by University of Michigan researchers and their colleagues at the National Institute on Aging, the study used the latest genetic tools to probe DNA molecules in unprecedented detail, uncovering new clues to humanity's origins.
The latest study characterizes more than 500,000 DNA markers in the human genome and examines variations across 29 populations on five continents. "Our study is one of the first in a new wave of extremely high-resolution genome scans of population genetic variation," said Rosenberg, an assistant research professor at U-M's Life Sciences Institute and co-senior author of the study.
"Now that we have the technology to look at thousands, or even hundreds of thousands, of genetic markers, we can infer human population relationships and ancient migrations at a finer level of resolution than has previously been possible," he added.
The new study produced genetic data nearly 100 times more detailed than previous worldwide assessments of human populations.
The study determines that it's sometimes possible to trace a person's ancestry to an individual population within a geographic region.
"While previous studies have found that broad-scale geographic ancestry could be successfully traced, the new results indicate it's becoming increasingly possible to use genomics to refine the geographic position of an individual's ancestors with more and more precision," said Rosenberg.
"I hope the study will be an invaluable resource for understanding genomic variability and investigating genetic association with disease," said the NIA's Singleton.
The researchers analyzed DNA from 485 people. They examined three types of genetic variation: single-nucleotide polymorphisms, or SNPs; haplotypes; and CNVs.
If the human genome is viewed as a 3-billion-letter book of life, then SNPs represent single-letter spelling changes, haplotype variations equate to word changes, and CNVs are wholesale deletions or duplications of full pages.
The patterns revealed by the new study support the idea that humans originated in Africa, then spread into the Middle East, followed by Europe and Asia, the Pacific Islands, and finally to the Americas.
The results also bolster the notion of "serial founder effects," meaning that as people began migrating eastward from East Africa about 100,000 years ago, each successive wave of migrants carried a subset of the genetic variation held by previous groups.
"Diversity has been eroded through the migration process," said Rosenberg.