"A study published by 22 authors (including myself) in the scientific journal Nature Genetics in November 2000 stated the results clearly and succinctly. A worldwide sample of men, from dozens of populations on every continent, were studied using the newly discovered treasure trove of Y-chromosome polymorphisms [only the male of the human species carries the Y-chromosome]. Applying the same methods used in the earlier mitochondrial DNA studies [women alone pass along the mitochondrial DNA], a tree diagram was constructed from the pattern of sequence variation. What this diagram showed was that the oldest splits in the ancestry of the Y chromosome occurred in Africa. In other words, the root of the male family tree was placed in Africa -- exactly the same answer that mitochrondrial DNA had given us for women. The shocker came when a date was estimated for the age of the oldest common ancestor. This man, from whom all men alive today ultimately derive their Y-chromosomes lived 59,000 years ago. More than 80,000 years after that estimated for 'Eve!' Did 'Adam' and 'Eve' never meet? No they didn't, but the reason is fairly complicated, and it reveals one of the most important things to remember about the study of human history with genetic methods... Such dates do not represent the date of origin of our species -- otherwise 'Eve' would have been waiting a long time for 'Adam' to show up. They simply represent the time, peering back into the past, when we stop seeing genetic diversity in our mitochondrial DNA and Y-chromosome lineages... As we'll see... the age difference between 'Adam' and 'Eve' is larger than we would expect by chance, and is probably the result of thousands of years of sexual politics [or two reproductive bottle-necks in the human geneologcial tree separated by tens of thousands of years? -- E.T.B.]. It is not, though, indicative of any deep uncertainties about human evolution. [Though it might be indicative of uncertainties about taking Genesis literally. -- E.T.B.]" [Spencer Wells, The Journey of Man: A Genetic Odyssey (Princeton, N.J.: Princeton University Press, 2002), p. 53-55. (Well's book has also been made into a television series broadcast on PBS.)]
What is most interesting, above, is the way that the geneticists, have been able to minutely compare differences in the DNA from human beings round the world and determine the most likely ways those differences had accrued over time, just like examining a pile of similar but not identical "chain letters," noting which ones had certain sentences added, or changed round, or had certain punctuation added or removed, tracing the trail of changes made in such chain letters backward in time toward what earlier versions most probably looked like. If you have enough similar chain letters to compare, it's easy to see how this tracing-backward process can be done, and why it works. In fact there was an article about comparing chain-letters and how that relates to tracing back DNA patterns in SCIENTIFIC AMERICAN, "Chain Letters and Evolutionary Histories;" June 2003; by Charles H. Bennett, Ming Li and Bin Ma:
IN OUR HANDS ARE 33 VERSIONS OF A CHAIN LETTER, collected between 1980 and 1995, when photocopiers, but not e-mail, were in widespread use by the general public. These letters have passed from host to host, mutating and evolving. Like a gene, their average length is about 2,000 characters. Like a potent virus, the letter threatens to kill you and induces you to pass it on to your "friends and associates"-some variation of this letter has probably reached millions of people. Like an inheritable trait, it promises benefits for you and the people you pass it on to. Like genomes, chain letters undergo natural selection and sometimes parts even get transferred between coexisting "species." Unlike DNA, however, these letters are easy to read. Indeed, their readability makes them especially suitable for classroom teaching of phylogeny (evolutionary history) free from the arcana of molecular biology. The letters are an intriguing social phenomenon, but we are also interested in them because they provide a test bed for the algorithms used in molecular biology to infer phylogenetic trees from the genomes of existing organisms. We believe that if these algorithms are to be trusted, they should produce good results when applied to chain letters. Using a new algorithm that is general enough to have wide applicability to such problems, we have reconstructed the evolutionary history of our 33 letters [see illustration on page 79]. The standard methods do not work as well on these letters. Originally developed for genomes, our algorithm has also been applied to languages and used to detect plagiarism in student assignments: anything involving a sequence of symbols is grist for its mill. [END OF QUOTATION FROM SCIENTIFIC AMERICAN ARTICLE]
Geneticists continue making the most detailed maps of the DNA of each species, and will soon be able to trace more and more of their lineages backward in time by comparing the minute differences that have accrued in their DNA as they split off from each other. That's how they were able to determine that contemporary human beings came out of AFRICA -- as discussed in the first paragraph of this article. Meanwhile, Genesis says that Noah landed in the mountains of Ararat in modern day Armenia, NOT AFRICA, and Genesis goes on to claim that people settled in the "valley of Shinar" not very far from where Noah landed, and there they built the first major "city and tower," and then (after the "confusion of tongues"), they spread to the rest of the world. So the story in Genesis does not match the story in our genes.
Another case of such research was recently reported in NEW SCIENTIST (July 24-30, 2004, "Oz Origins for Perching Birds") that said scientists had studied the DNA of 144 species of passerines (perching birds) and discovered evidence that "suggests that the passerines began diversifying about 82 million years ago, when New Zealand split from Austalia. A major split within the lineage, between songbirds and a second group, came around 65 milion years ago. The songbirds later spread from Australia through Asia, while the others, a group containing flycatchers and ant birds, spread across South America." Again, as in the case of man, no evidence that the songbirds split from the other groups anywhere near the mountains of Armenia where Noah's ark allegedly landed. So it would seem that the story of Noah's ark remains doubtful in light of an increasing array of modern day genetic comparisons.
Cheers!
Ed
