NYT: Study says near extinction threatened people

[shireen]

This is fascinating ....

http://www.nytimes.com/aponline/us/AP-Close-Call.html


Study says near extinction threatened people

By THE ASSOCIATED PRESS
Published: April 24, 2008
Filed at 7:10 p.m. ET

WASHINGTON (AP) -- Human beings may have had a brush with extinction 70,000 years ago, an extensive genetic study suggests. The human population at that time was reduced to small isolated groups in Africa, apparently because of drought, according to an analysis released Thursday.

The report notes that a separate study by researchers at Stanford University estimated the number of early humans may have shrunk as low as 2,000 before numbers began to expand again in the early Stone Age.

''This study illustrates the extraordinary power of genetics to reveal insights into some of the key events in our species' history,'' Spencer Wells, National Geographic Society explorer in residence, said in a statement. ''Tiny bands of early humans, forced apart by harsh environmental conditions, coming back from the brink to reunite and populate the world. Truly an epic drama, written in our DNA.''

Wells is director of the Genographic Project, launched in 2005 to study anthropology using genetics. The report was published in the American Journal of Human Genetics.


Recently, I submitted my DNA to the Genographic project to find out more about my early ancestry. Got the results last week, and it was really cool! According to the analysis, I belong to mtDNA haplogroup M. This was probably the first group of humans to leave Africa, about 60,000 years ago. This group "spread out" across the Middle East, into Asia, northern India, down Southeast Asia, to Australia (there are sub-groups but I need to do a second test to refine the results). A friend of mine submitted her DNA as well, and we learned she was in haplogroup H, which entered western Europe about 15,000 years ago. I bought a kit for my brother so we could get a Y-chromosome analysis to learn more about our father's paternal ancestry.

The kit costs $100 ... a chunk of it goes towards funding further studies. If you can afford it, and you're curious about human prehistoric migrations, it's worth it!

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

[WCGreen]

1. That means we are all probably retlated to each other..

No matter what the racists seem to believe.

[datopbanana]

4. you catch on quick.

[Fridays Child]

2. I had the mtDNA test, too.

I did the basic test as well as the second one to refine the results. I confess I haven't tried to decipher all the information but I did learn the area of the world that my maternal ancestors came from. Among those who agreed to let their information be shared, three women have the same results as me, so far. It's pretty neat stuff.

[Turbineguy]

3. That must mean

that George Bush was here before.

[HamdenRice]

5. Something similar happened to cheetahs

I remember reading about this some years ago. Genetic studies revealed that the cheetah was almost extinct and came back from the brink. As a result they have much less genetic diversity than other big cats.

On edit: This is pretty remarkable:

http://american.edu/ted/cheetah.htm

With the onset of the last Ice Age, approximately 10,000 years ago, all the cheetah in North America, Europe, and most of those in Asia and Africa perished. From the those cheetah that survived are descended the current stock of cheetah. The present day population of cheetah are derived from inbreeding by those very few surviving populations and closely related animals. This created the genetic "bottleneck", that has led to the present genetic state of cheetah such that all living cheetah today are more closely related than identical twins, with less than one percent genetic diversity as compared to a human's thirty-seven percent...

On second edit, WoW!

http://www.newscientist.com/article/mg13818753.000-science-cheetahs-teetered-on-brink-in-the-ice-age-.html

They assumed that at one time only one litter of cheetahs survived a near-extinction, so there would have been hardly any genetic variation. By counting the number of mutations that have occurred since then in a specific part of the DNA, they could estimate when this near-extinction happened.

[FiveGoodMen]

6. "all living cheetah today are more closely related than identical twins"

Identical twins have exactly the same DNA. Exactly.

[FiveGoodMen]

7. This discrepancy doesn't bother anyone else here in the science forum?

[HamdenRice]

8. No. Here's why--->

While the author may have mispoke by saying that they are more similar than genetic twins his larger points is that cheetah are more inbred than genetic twins.

Google: cheetah genetic "identical twins" -- and you will find hundreds of hits that basically state that all cheetah are essentially identical twins or clones. It's a pretty remarkable story. Several thousand years ago all cheetah died out except for one last litter. Since then, all living cheetah have descended from that litter through inbreeding.

So while human twins are clones of each other, they are not inbred. What the author meant is that cheetah are both clones and inbred clones -- which makes them more of a genetic oddity than human twins.

Something like 30% of all cheetah cubs die, just from genetic inbreeding problems -- a much higher rate than other big cats.

Also, modern genetics is presenting a more complex picture of genetics than the simple statement that "identical twins have identical DNA." We now know that, in utero, some genes are turned off or on and that there are copy number variations - so it is possible for some twins to be more genetically identical than others.

http://www.sciam.com/article.cfm?id=identical-twins-genes-are-not-identical

April 3, 2008

Identical Twins' Genes Are Not Identical

[Benfea]

9. The contents of this article are obviously false

They claim that the human race was nearly wiped out 64,000 years before GOD created the universe.

[Indenturedebtor]

10. I agree

This DNA goo was put here by the devil to make us all homosexuals. We must continue to resist the urges and find some little boys to molest instead :crazy: