''Out of Africa'' human tour traced through DNA

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New York, Feb 21 (UNI) Diving into the details of human gene pool, scientists have traced new clues to humanity's origin in Africa.

A new study by researchers at the Michigan University revealed that humans originated in Africa, then spread to the West Asia followed by Europe and Asia, the Pacific Islands, and finally to the Americas.

The largest and the most detailed worldwide study of human gentic variation uses the latest genetic tools to probe DNA molecules in unprecedented detail.

The latest study characterises more than 500,000 DNA markers in the human genome and examines variations across 29 populations on five continents.

''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.'' It is 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 published in Journal Nature indicate that geographic position of an individual's ancestor could be known with more precision.

According to researchers, human genetic diversity decreases as distance from Africa --the cradle of humanity-- increases. People of African descent are more genetically diverse than West Asianers, who are more diverse than Asians and Europeans. Native Asians possess the least-diverse genomes.

As a result, searching for disease-causing genes should require the fewest number of genetic markers among Native Americans and the greatest number of markers among Africans.

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, lead researcher Noah Rosenberg said.

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