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Genographics

 

New scientific methods for determining genetic affiliation, substructure and gene flow within human populations is now done through the science of genetics.

This science has also taken a keen interest in the identification of human individuals and genetic relationships between individuals. Since the genome of an individual is unique to that individual, and can be used for identification purposes, e.g., testing for paternity and/or forensic testing (e.g. to identify an individual in the context of post-mortem identification or in the criminal justice system). Procedures have been developed which are based on identification and characterization of changes in an individual’s DNA, referred to as DNA polymorphisms.

Comparisons of DNA sequences can be done for pairs of individuals from the same population or for pairs of individuals from different populations. Populations can be defined in various ways; one common way is to group individuals into populations according to a continent of origin. Using this definition, individuals from different populations have roughly 10 percent to 15 percent more sequence differences than do individuals from the same population. (This is how investigators in Hariri’s assassination were able to locate the origins of the person who detonated the Mitsubishi truck).

 

The Genographic Project, launched in April 2005, is a five-year genetic anthropology study that aims to map historical human migration patterns by collecting and analyzing DNA samples from hundreds of thousands of people from around the world.

Field researchers at 10 regional centers around the world collect DNA samples from indigenous populations. To help ordinary people like you and me get involved in the program, a company was set up by National Geographic, IBM and the Waitt family that sells self-testing kits: for US$100 anyone in the world can order a self-testing kit from which a mouth scraping (buccal swab) is obtained, analyzed and the DNA information placed on an Internet accessible database. The genetic markers on mitochondrial DNA and Y-chromosomes are used to trace the customer’s distant ancestry, and each customer is provided with their genetic history. As of June 2008, more than 270,000 people have bought a test kit.

The US$40m project is a privately-funded, nonprofit collaboration between the National Geographic Society, IBM and the Waitt Family Foundation. Part of the proceeds from the sale of self-testing kits support the Genographic Project’s ongoing DNA collection, but the majority are ploughed into a Legacy Fund to be spent on cultural preservation projects nominated by indigenous communities.

Exodus from Africa:

Some scientists believe that only a few people left Africa in a single migration that went on to populate the rest of the world. It has been estimated that from a population of 2,000 to 5,000 in Africa, only a small group of possibly 150 people crossed the Red Sea.

Other scientists propose a Multiple Dispersals Model, in which there were two migrations out of Africa, one across the Red Sea travelling along the coastal regions to India (the Coastal Route), which would be represented by Haplogroup M; while another group of migrants with Haplogroup N followed the Nile from East Africa, heading northwards and crossing into Asia through the Sinai. This group then branched in several directions, some moving into Europe and others heading east into Asia:

What is the population history of modern Homo sapiens, and how did that history contribute to the current structure of human populations?

Information about the history of the human species comes from two main sources: bones (Mitochondrial DNA) and artifacts gathered from archaeological sites, and the distribution of genetic variants in the human population today. Both sources of information are fragmentary, but both are converging on the same general story.

The earliest fossil skull with features similar to those of anatomically modern humans (including a rounded braincase, reduced brow ridges, and a distinct chin) comes from Ethiopia’s Omo River and is estimated to be about 190,000 years old. Later fossils (with estimated ages) that have at least some modern characteristics have been found elsewhere in Ethiopia (150,000 years), in the Middle East (100,000 years), in southern Africa (100,000 years), in Australia (40,000 years), in eastern Europe (35,000), and in the Americas (13,000 years).

 

Using the new applications in genomics, these discoveries suggest that anatomically modern humans evolved in Eastern Africa and then spread out to occupy the rest of Africa, Asia, Europe, and the Americas (see Figure below):



A map showing the dispersal of modern humans out of
Africa, Nature 408(6813)

Genetic evidence supports this conclusion. The genetic diversity of indigenous human populations drops with increasing geographic distance from Eastern Africa. One would expect this pattern if groups of migrants moving away from Africa carried with them just part of the genetic variation existing in Africa. Consistent with this picture, the broad patterns of genetic variation found outside Africa tend to be a subset of those found inside Africa.

Populations of archaic humans lived in Africa and Eurasia as modern humans expanded outward from eastern Africa, including Neanderthals in Europe and Homo erectus in Asia. Some fossil and genetic evidence suggests that modern humans interbred with these archaic humans during their expansion, so that some genetic variants from these populations may still be present in modern populations. But the genetic evidence also indicates that the amount of interbreeding must have been small if it occurred at all. Most of the genetic differences between human populations today appear to have developed as populations of modern humans became widely dispersed during their worldwide expansion

 

If you want to participate in the project, this is where you can buy the kit:

 

https://www3.nationalgeographic.com/genographic/participate.html

 

SO, how about spending $100 to find who your old old Dad really is!

 

 

 

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