Indian DNA Links to 6 'Founding Mothers'

[mangxema]

...By MALCOLM RITTER

NEW YORK (AP) -- Nearly all of today's Native Americans in North, Central and South America can trace part of their ancestry to six women whose descendants immigrated around 20,000 years ago, a DNA study suggests.

Those women left a particular DNA legacy that persists to today in about about 95 percent of Native Americans, researchers said.

The finding does not mean that only these six women gave rise to the migrants who crossed into North America from Asia in the initial populating of the continent, said study co-author Ugo Perego.

The women lived between 18,000 and 21,000 years ago, though not necessarily at exactly the same time, he said.

The work was published this week by the journal PLoS One. Perego is from the Sorenson Molecular Genealogy Foundation in Salt Lake City and the University of Pavia in Italy.

The work confirms previous indications of the six maternal lineages, he said. But an expert unconnected with the study said the findings left some questions unanswered.

Perego and his colleagues traced the history of a particular kind of DNA that represents just a tiny fraction of the human genetic material, and reflects only a piece of a person's ancestry.

This DNA is found in the mitochondria, the power plants of cells. Unlike the DNA found in the nucleus, mitochondrial DNA is passed along only by the mother. So it follows a lineage that connects a person to his or her mother, then the mother's mother, and so on.

The researchers created a "family tree" that traces the different mitochondrial DNA lineages found in today's Native Americans. By noting mutations in each branch and applying a formula for how often such mutations arise, they calculated how old each branch was. That indicated when each branch arose in a single woman.

The six "founding mothers" apparently did not live in Asia because the DNA signatures they left behind aren't found there, Perego said. They probably lived in Beringia, the now-submerged land bridge that stetched to North America, he said.

Connie Mulligan of the University of Florida, an anthropolgist who studies the colonization of the Americas but didn't participate in the new work, said it's not surprising to trace the mitochondrial DNA to six women. "It's an OK number to start with right now," but further work may change it slightly, she said.

That finding doesn't answer the bigger questions of where those women lived, or of how many people left Beringia to colonize the Americas, she said Thursday.

The estimate for when the women lived is open to question because it's not clear whether the researchers properly accounted for differing mutation rates in mitochondrial DNA, she said. Further work could change the estimate, "possibly dramatically," she said.

Just 6? Wow.

 

[Godwynn]

I thought all humans had a common male ancestor in the North-East side of Africa?

 

[Norseone]

Yeah...but thats a long long time ago(much longer than this). Mitochondrial DNA is direct descendant DNA though so this is kinda cool, thats quite a population bottleneck.

 

[Eran of Arcadia]

That is just mtDNA, right? So that means that anyone with Native American ancestry is descended in a direct female line from 6 people, but of course have countless more contemporary ancestors.

 

[StarWorms]

Yeah...but thats a long long time ago(much longer than this). Mitochondrial DNA is direct descendant DNA though so this is kinda cool, thats quite a population bottleneck.

It doesn't suggest any kind of bottleneck.

If you go back far enough, everyone alive today will be descended from one man, and one woman.

 

[Eran of Arcadia]

But apparently the woman and the man lived at very different times.

And the entire human race has more ancestors in common, probably. These two individuals are just the source of our mtDNA and Y chromosomes, respectively.

 

[Norseone]

It doesn't suggest any kind of bottleneck.

If you go back far enough, everyone alive today will be descended from one man, and one woman.

it does suggest a bottleneck because most groups have more ancestors than 6 20k years ago

 

[TheLastOne36]

wasn't there some founding not to long ago about all/(most?) humans on the earth can be traced to 4 common mothers?

 

[taper]

Mitochondrial Eve and Y Chromosomal Adam. These two are much older than these 6, and lived in different times and places, but virtually everybody is directly descended from both of them.

 

[Bast]

So interesting. Well that's their legacy to the human race I guess. LOL

 

[Rashiminos]

I thought all humans had a common male ancestor in the North-East side of Africa?

Female ancestor, and yes.

 

[Norseone]

The point is this is a very recent time for 6 common ancestors. The point is so many differently breed that everyone is related to one person far enough back. But, this indicates the Native American population was formed by a very small founder population. I bet this contributed to the utter destruction wrought by Smallpox, mono culture will do that.

 

[West 36]

How many 'greats' do I need to attach to grandmother/father to make this feel more loving and personal?

 

[lutzj]

How many 'greats' do I need to attach to grandmother/father to make this feel more loving and personal?

Assuming 20 years per generation (which is probably a little high):
Mitochondrial Eve live roughly 140,000 years ago, so you would need around 7000 "greats"; Y-chromosomal Adam lived 60,000 years ago, so you would need 3000.

 

[Elta]

How many 'greats' do I need to attach to grandmother/father to make this feel more loving and personal?

The estimates they gave are off of an *estimated birthage of the mother as 18 so:
20k divided by 18 so 1,111 generations back

*Something I remembered from Physical Anthropology .... no links

 

[Elta]

Assuming 20 years per generation (which is probably a little high):
Mitochondrial Eve live roughly 140,000 years ago, so you would need around 7000 "greats"; Y-chromosomal Adam lived 60,000 years ago, so you would need 3000.

P.S. in case anyone was wondering the estimate is off of each women having 4 children half female half male and the average birthing age is 18.

Not entirely accurate as to what really goes on, but a rough idea

 

[h4ppy]

Not surprising, this doesn't mean that only six women originally crossed over, of course, just that the people who crossed over were descended from six women.

 

[Knight-Dragon]

The thread title is very misleading. I was expecting the article to be about Asian Indians, not Native Americans...

 

[StarWorms]

it does suggest a bottleneck because most groups have more ancestors than 6 20k years ago

No it doesn't, there can be many reasons. One of which could be that there was migration to that area by small groups of people.

How many 'greats' do I need to attach to grandmother/father to make this feel more loving and personal?

About 800...

 

[GenMarshall]

The thread title is very misleading. I was expecting the article to be about Asian Indians, not Native Americans...

Ditto, you're not the only one .