Link (http://www.efluxmedia.com/news_DNA_Links_Humanity_To_One_Common_Origin_Afric a_14333.html)

So one of the 2 theories has finally been proven, now we can get on with the future.

Have you ever been to Africa? According to the latest studies on human diversity, you have! Scientists identified that sub-Saharan Africa is the place where the human migration phenomenon began 100,000 years ago, when a small group of humans headed for North Africa and Middle East, and kept on going ever since, reaching the farthest continents of Americas and Australia.

Up until this point, theories on a global migration with an African starting point have been circulating, but none of them brought the arguments and evidence this study did on the topic. “It’s like looking back at the earth with a telescope a thousand times more powerful than what you had before,” said Richard Myers from Stanford University school of Medicine, the journal Science reports.

Two studies have already been published in the journals Science and Nature on the patterns of genetic mutations and human diversity, and based on the similar DNA samples, proved one common conclusion: the modern human left Africa (Addis Ababa, Ethiopia to be more precise), traversed Central Asia and continued heading east and west to Europe, Asia and Americas.

Another genetic study, similar to the other two and published in the journal Nature, concluded that after the African migration, the newly settled European population started losing its genetic diversity and at the same time, while continuing to expand on the continent, they started accumulating a series of genetic mutations before older ones, with potentially negative impacts, have had the chance to wear out.

What was very surprising was that many of the groups thought to have one well established origin actually presented traces to several continents. This was the case of the Bedouins in the Middle East, who were traced back to Europe and Pakistan, or the Yakut population, who should have the most similarities with the Siberians, but actually relate to East Asia, Europe and American Indians.

The conclusion draw attention to the fact that we are much more related than we think we are, curiously enough, to people on different parts of the world, more than we are to people around us. “A huge amount of our genomes are the same across the world, and that helps to argue against racism in my view,” Myers said the journal Nature.

How do they use DNA to link back to anywhere?

Correction, BL: Africa is the earliest point in human migration--that we know of.

How do they use DNA to link back to anywhere?Using stuff like mitochondrial DNA.

Mutations gradually arise and you can map them using the knowledge of where each group is located today in indigenous populations. The most primitive groups lacking mutations found in nearly all other groups are found in Africa.


Here's one which is for Y-DNA (the same principle applies):

http://www.white-history.com/ychromo_files/ychromo.gif

How do they use DNA to link back to anywhere?

What Starworms says, and you use bones to get the ancient DNA.

Correction, BL: Africa is the earliest point in human migration--that we know of.

Well if you can go out and find something totally new which had never before been seen which could have been modern humans not in africa before that, good luck to you....

Just to expound:
http://en.wikipedia.org/wiki/Mitochondrial_DNA


Among multicellular animals (metazoans), nearly all of the mtDNA in a fertilized egg (zygote) is inherited from only one parent—the female. One mechanism for this is simple dilution: an egg contains 100,000 to 1,000,000 mitochondria, whereas a sperm contains only 10 to 100.

Female inheritance
In sexually reproducing organisms, mitochondria are normally inherited exclusively from the mother. The mitochondria in mammalian sperm are usually destroyed by the egg cell after fertilization.
Use in identification



Unlike nuclear DNA, which is inherited from both parents and in which genes are rearranged in the process of recombination, there is usually no change in mtDNA from parent to offspring. Although mtDNA also recombines, it does so with copies of itself within the same mitochondrion. Because of this and because the mutation rate of animal mtDNA is higher than that of nuclear DNA,[2] mtDNA is a powerful tool for tracking ancestry through females (matrilineage) and has been used in this role to track the ancestry of many species back hundreds of generations. Human mtDNA can be used to identify individuals.[3]

Because the base sequence of animal mtDNA changes rapidly, it is useful for assessing genetic relationships of individuals or groups within a species and also for identifying and quantifying the phylogeny (evolutionary relationships; see phylogenetics) among different species, provided they are not too distantly related. To do this, biologists determine and then compare the mtDNA sequences from different individuals or species. Data from the comparisons is used to construct a network of relationships among the sequences, which provides an estimate of the relationships among the individuals or species from which the mtDNAs were taken. This approach has limits that are imposed by the rate of mtDNA sequence change. In animals, the rapid rate of change makes mtDNA most useful for comparisons of individuals within species and for comparisons of species that are closely or moderately-closely related, among which the number of sequence differences can be easily counted. As the species become more distantly related, the number of sequence differences becomes very large; changes begin to accumulate on changes until an accurate count becomes impossible.

Correction, BL: Africa is the earliest point in human migration--that we know of.

Bah, all our close living relatives are indigenous to that continent, the case seems rather clear.

I don't care where we came from. We are one species, that's what really matters.