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Age of Our Ancestors-How Our Genetic Adam Is Much Younger than Genetic Eve
abcnews.go.com ^

Posted on 02/02/2004 12:31:53 AM PST by chance33_98

Age of Our Ancestors

How Our Genetic Adam Is Much Younger than Genetic Eve

Commentary By John Allen Paulos

Feb. 1 — A new book, The Journey of Man, demonstrates how recent advances in genetics, particularly those involving the Y-chromosome, allow us to follow the arc of human migration out of Africa, our ancestral home.

Although Neanderthals and other hominids related to Homo sapiens date back hundreds of thousands of years, the book's author, geneticist Spencer Wells, shows that our origins are much more recent. Presenting the work of Luigi Luca Cavalli-Sforza, Richard Lewontin, and other eminent researchers, Wells argues convincingly that all men on earth (the Y-chromosome is passed only from father to son) can trace their roots to a particular male who lived in Africa, almost 60,000 years ago.

Likewise, all humans on earth can trace their lineage through our maternally inherited mitochondrial DNA back to a particular woman, who lived in Africa roughly 150,000 years ago. This "Adam" is my great-grandfather roughly 2500 times removed and this "Eve" my great grandmother roughly 6500 times removed. (Yours too, so we're all distant cousins.)

In coming to these conclusions, Wells relies upon a variety of mathematical techniques, ranging from statistical tests to measure the similarities between and among the genomes of present-day populations to carbon dating and other methods commonly employed at archeological sites.

The probability of branching processes lends additional support as does empirical research on the world's various ethnic groups. Most revealing is the use of the rate at which random mutations naturally occur to infer the paths of our ancestors around the globe.

Family Recipes as a Metaphor

Wells employs a culinary metaphor to clarify the notion of a genetic Eve, whose existence was long disputed by those who believed that mankind developed independently in several locations around the world. Altering Wells' metaphor a little, let's imagine a small village that has been inhabited for millennia. Imagine further that we go way back in time and note that the few families in the village use different recipes for their primary meal, and that the recipes are handed down from mother to daughter only.

Very complex, the recipes can be modified in hundreds of ways — a different ingredient here, longer cooking time there, etc. — and every once in a while a daughter makes a tiny change in her mother's recipe, which she then passes down to her daughter(s). Sometimes because of accident, disease, or simply a line's not having any daughters, a family's recipe and its variants die out. In fact, let's assume that all but one of the original recipes and their variants disappear. Thus in the village we can now find only one of the dozen original recipes, dating back X thousand years, and its many variants.

If for the village we substitute Africa, and for recipes we substitute the human genome, the surviving original recipe is analogous to the genetic makeup of African Eve since all the surviving recipes derive from it just as we all can trace all our mitochondrial DNA back to a particular woman who lived 150,000 years ago.

And just as our mitochondrial DNA is inherited only through our mothers, the male Y-chromosome is passed only from fathers to sons. So let's invent another just-so story about, say, elaborate hunting rituals that are passed down from father to son with very rare changes. We again go back to a time when there were very few families and hence few different hunting rituals.

Once again, each of these elaborate hunting rituals changes very slowly. Furthermore, because of famine, disease, or not having any sons, a family's hunting ritual and its variants die out. Let's assume that all but one of the original rituals and their variants disappear. Thus in the village we can find only one of the few original rituals, dating back Y thousand years, and its many variants, and thus conclude that all existing rituals derive from the original one, the analogue of a genetic Adam.

The Paths We Took

Note that X and Y need not be equal since recipes and hunting rituals will no doubt change and die out at different rates, so our genetic Eve did not meet our genetic Adam (and both, of course, had parents, grandparents, and other progenitors).

There is, however, much more in Journey than this absence of a prehistoric romance. As mentioned, the bulk of the book examines how geneticists study small changes in the DNA of our Y-chromosomes and use the rate at which they naturally occur as a sort of molecular clock to determine when and where various groups and clans of our prehistoric ancestors split off and spread over the earth (along the coast of India to Australia, later into Eurasia, and then down to the Americas across the Bering Sea).

If we know where we originated, and if a distinct recipe or ritual and its descendants, to revert to our metaphor, appears only in a neighboring village, then this (along with much other evidence) indicates that these people left the original village at a certain time. And if their descendants' recipes and rituals appear only in an even more distant village, then these others left still later.

The common childhood game in which we change, a letter at a time, one sequence of letters into another — say GENE to GONE to GORE to MORE to MARE to MARS — also sheds some light on what geneticists do when analyzing the branching changes in the very long sequence of "letters" that constitute our DNA. If each of the changing sequences of letters also gave rise to other changing sequences of letters and if some of these sequences split off and moved to different physical locations, we would be led to the sort of considerations and methods that are described in The Journey of Man.

We've come a long way, and the fascinating, sometimes counterintuitive details of the trip are finally becoming a little clearer.


TOPICS: Miscellaneous
KEYWORDS: archaeology; dna; genetics; ggg; godsgravesglyphs; history
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1 posted on 02/02/2004 12:31:56 AM PST by chance33_98
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To: farmfriend; blam
Ping
2 posted on 02/02/2004 12:32:23 AM PST by chance33_98 (Check out profile page for banners, if you need one freepmail me and I will make one for you)
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To: chance33_98; *Gods, Graves, Glyphs; A.J.Armitage; abner; adam_az; AdmSmith; Alas Babylon!; ...
Gods, Graves, Glyphs
List for articles regarding early civilizations , life of all forms, - dinosaurs - etc.

Let me know if you wish to be added or removed from this ping list.

3 posted on 02/02/2004 12:36:03 AM PST by farmfriend ( Isaiah 55:10,11)
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To: chance33_98
Just because "Adam" died in Africa does not mean he lived there! Just because you find ones bones in a place does not mean he lived there! "Adam" could have wondered from place to place! "Adam" could be a person of special importance and his bones could have been taken to Africa as a sign of reverance! The Catholic Church has lots of bones of "saints" who were stolen and moved to places for worship!
4 posted on 02/02/2004 12:47:12 AM PST by KingNo155
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To: KingNo155
seems like this is a pc article to game "eve" as first.

If anything it tells me that the survival characteristics of the Y carrying humans had more selection activity than the X. Thus given hunting and warfare etc., the weaker Y's were killed off by environment and stronger Y's. The X's were not under such survival strain and thus did not have to be as genetically selective for survivale traits.

The X is "older" because it has had to change less. (keep in mind all men are X and Y not just Y. women=XX men=XY Just in case anyone missed that part from the article) The Y is newer because the Y model one was killed off in favor of Y model two.

(s)so in essence this ABC story is saying that women are less evolved than men. (/s)
5 posted on 02/02/2004 12:56:52 AM PST by longtermmemmory (Vote!)
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To: longtermmemmory
Well of course women are less evolved than men...... that's why we don't have that urge to hog the TV remote....LOL
6 posted on 02/02/2004 3:24:42 AM PST by Apple Pan Dowdy (... as American as Apple Pie)
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To: KingNo155
You seriously expect a primitive creature that walks very slowly and is defenseless to move vast distances in a lifetime 60,000 years ago before the discovery of the wheel, before domestication of any animals? He could only have lived in Afrique
7 posted on 02/02/2004 3:40:59 AM PST by Cronos (W2004!)
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To: KingNo155
Words fail me
8 posted on 02/02/2004 4:02:50 AM PST by Oztrich Boy (It is always tempting to impute unlikely virtues to the cute)
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To: PatrickHenry; VadeRetro; Piltdown_Woman; RadioAstronomer; Ichneumon
Ping...
9 posted on 02/02/2004 4:32:05 AM PST by Junior (Some people follow their dreams. Others hunt theirs down and beat them mercilessly into submission)
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To: KingNo155
Catholics have never worshipped bones. Just an FYI.
10 posted on 02/02/2004 4:59:46 AM PST by TheGeezer
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To: chance33_98
It might be true... Of course, who knows? These days scientists spend a lot of effort trying to disprove the account of Genesis. Maybe the whole thing is a big fraud.
11 posted on 02/02/2004 5:01:16 AM PST by Brilliant
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To: KingNo155
"Adam" could be a person of special importance and his bones could have been taken to Africa as a sign of reverance!

Sure, but there's no way to determine whether that is true or not. Most likely, not. People of the time were hunter-gatherers who travelled with nothing but what they could carry.

12 posted on 02/02/2004 6:23:19 AM PST by Modernman ("The details of my life are quite inconsequential...." - Dr. Evil)
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To: Brilliant
These days scientists spend a lot of effort trying to disprove the account of Genesis.

Yup. Scientists spend their time trying to disprove the tenets of Christianity. I'd love to see an example.

13 posted on 02/02/2004 6:24:59 AM PST by Modernman ("The details of my life are quite inconsequential...." - Dr. Evil)
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To: farmfriend
Please add me to your Gods Glyphs ping list.........thanks
14 posted on 02/02/2004 6:33:37 AM PST by jeremiah (Sunshine scares all of them, for they all are cockaroaches)
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To: KingNo155
So what if it's Africa?
15 posted on 02/02/2004 6:48:57 AM PST by cyborg
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To: TheGeezer
Catholics have never worshipped bones. Just an FYI.

What's reverentially placed in the alter of every Catholic church?

16 posted on 02/02/2004 6:53:14 AM PST by SengirV
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To: chance33_98
" Eve, whose existence was long disputed by those who believed that mankind developed independently in several locations around the world.

I still believe this.

17 posted on 02/02/2004 8:10:35 AM PST by blam
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To: KingNo155
It's not about bones. They study the DNA of living people in order to determine how they are related. People still living in Africa today have DNA that is far more similar to that of the people they are calling "Eve" and "Adam" than yours is or mine is - unless you're African. A group of people living today in the north-western Kalahari desert in southern Africa is the population that is closest to the root of the human DNA tree.
18 posted on 02/02/2004 9:11:23 AM PST by CobaltBlue
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To: SengirV
Mary.
19 posted on 02/02/2004 9:15:11 AM PST by StoneColdGOP (McClintock - In Your Heart, You Know He's Right)
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To: longtermmemmory
Everybody alive today has inherited their mitochondrial DNA from the same woman who lived 120 million years ago. And everybody alive today has inherited their cellular DNA from the same man who lived 60 million years ago. That's what the article is saying.

20 posted on 02/02/2004 9:15:45 AM PST by CobaltBlue
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