 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Natural Science Forum / Biology / Paleontology / October 2006Article: Few Clues About African Ancestry To Be Found In Mitochondrial DNA
Few Clues About African Ancestry To Be Found In Mitochondrial DNA Mitochondrial DNA may not hold the key to your origins after all. A study published in the open access journal BMC Biology reveals that fewer than 10% of African American mitochondrial DNA sequences analysed can be matched to mitochondrial DNA from one single African ethnic group. There has been a growing interest in the use of mitochondrial DNA to trace maternal ancestries, and several companies now offer to analyse individuals' mitochondrial DNA sequences to obtain information about their origins. The current study suggests that only one in nine African Americans may be able to find clues about where their ancestors came from, in their mitochondrial DNA. Bert Ely, from the University of North Carolina, and colleagues from other Universities in the USA analysed a database of the human variable region, or HVS-1 region, of mitochondrial (mt) DNA sequences from sub-Saharan Africa. They then compared two samples of African American mt DNA sequences to the database, to identify exact matches to the sub-Saharan sequences. Ely et al.'s results show that more than half of the African American HSV-1 sequences were found in many different sub-Saharan ethnic groups. Forty percent of the African American HSV-1 sequences did not match any sequences in the database and fewer than 10% were an exact match to a sequence from a single African ethnic group. Article: African-American mitochondrial DNAs often match mtDNAs found in multiple African ethnic groups Bert Ely, Jamie L Wilson, Fatimah Jackson and Bruce A Jackson BMC Biology 2006, in press. Source: BioMed Central http://www.sciencedaily.com/releases/2006/10/061012185120.htm Posted by Robert Karl Stonjek Nice. Will you guys be able to link a half cast child of mongolian caucasion descent to it's original ... genetic splice (?) in regards to the first instance of Homo Sapien... at it's last branch.... > Few Clues About African Ancestry To Be Found In Mitochondrial DNA > Mitochondrial DNA may not hold the key to your origins after all. [quoted text clipped - 58 lines] > > ------=_NextPart_000_0945_01C6F0BD.10851480-- >Few Clues About African Ancestry To Be Found In Mitochondrial DNA >Mitochondrial DNA may not hold the key to your origins after all. [quoted text clipped - 23 lines] >Posted by >Robert Karl Stonjek Ely et al. appear to have been investigating the usefulness of information provided by the multitude of genealogy services who, for a fee, provide members of the general public with their mtDNA sequences: "Mitochondrial DNA (mtDNA) haplotypes have become popular tools for tracing maternal ancestry, and several companies offer this service to the general public. Numerous studies have demonstrated that human mtDNA haplotypes can be used with confidence to identify the continent where the haplotype originated. Ideally, mtDNA haplotypes could also be used to identify a particular country or ethnic group from which the maternal ancestor emanated. However, the geographic distribution of mtDNA haplotypes is greatly influenced by the movement of both individuals and population groups. Consequently, common mtDNA haplotypes are shared among multiple ethnic groups." http://tinyurl.com/y9fznu Here's the problem, as I see it. The mutations in the hypervariable regions are best-suited for determining populations movements which occurred several thousand years ago. In order to provide the general public with more specific information, complete sequences would have to be extracted - but these are, at the present time (at least), too expensive for the market. There are, generally, 2 or more coding region mutations for each one in the hypervariable regions. Gisele >>Few Clues About African Ancestry To Be Found In Mitochondrial DNA >>Mitochondrial DNA may not hold the key to your origins after all. [quoted text clipped - 65 lines] > > Gisele Do you have an opinion on all those does not match the data base? >>>Few Clues About African Ancestry To Be Found In Mitochondrial DNA >>>Mitochondrial DNA may not hold the key to your origins after all. [quoted text clipped - 69 lines] > > Do you have an opinion on all those does not match the data base? The database didn't sample every haplotype in the population? >>>Few Clues About African Ancestry To Be Found In Mitochondrial DNA >>>Mitochondrial DNA may not hold the key to your origins after all. [...] >>> Forty percent of the African American HSV-1 >>> sequences did not match any sequences in >>> the database ... >>>Article: African-American mitochondrial DNAs often match mtDNAs found in >>>multiple African ethnic groups [quoted text clipped - 3 lines] >>>Source: BioMed Central >>>http://www.sciencedaily.com/releases/2006/10/061012185120.htm [...] >Do you have an opinion on all those does not match the data base? I read the article this afternoon which is freely available, btw: http://www.biomedcentral.com/content/pdf/1741-7007-4-34.pdf The reasons are probably due to an inadequate database and errors as described below (hopefully in that order): "In both of the African-American samples, approximately 40% of the mtDNA sequences did not match any sequence in any other ethnic group (Table 3). However, more than half of these sequences differed from multiple database sequences at a single position (Table 4). Because it is unlikely that more than a few of these differences result from new mutations that occurred in North America or that more than a few lineages went extinct in Africa after being introduced to the new world, this result suggests that only a small fraction of the mtDNA diversity present in sub-Saharan Africa has been sampled, and that much of the unsampled diversity is due to single mutations that have occurred in the common haplotypes." "No attempt was made to correct any other errors that might be present among the published sequences. However, the presence of sequencing errors would have the effect of reducing the incidence of perfect matches so that the frequencies of perfect matches we observe should be considered minimum estimates." -------------------- Depending on the circumstances, I often consider sequences which are out by one, in the first hypervariable region, to still be matches. They often are exact matches in hypervariable region 2 (which was not compared in this study). Also, there could easily be more errors in African sequences than those of other continents for two reasons: 1) Many of the African samples were obtained long ago (i.e. 10 years) and 2) Since the reference sequence which is used is the most common European one, sub-saharan African sequences have many differences (up to 14 or so in HVR I) from it and these have to have been correctly identified and recorded to have exact matches. Many more Europeans and Asian mtDNA sequences are available for comparison than African and Australian. Gisele > Few Clues About African Ancestry To Be Found In Mitochondrial DNA > Mitochondrial DNA may not hold the key to your origins after all. [quoted text clipped - 58 lines] > > ------=_NextPart_000_0945_01C6F0BD.10851480-- Is there some deadness of brain here? Black Americans have married and interbred for as long as 400 years, so the traces of any African "ethnic groups" were long ago obliterated. > Is there some deadness of brain here? Black Americans have married and > interbred for as long as 400 years, so the traces of any African > "ethnic groups" were long ago obliterated. I don't know if they can or can't trace an ethnic group, but some pretty amazing things are being done just the same. It's getting harder and harder to hide. http://tinyurl.com/yxeb42 > Is there some deadness of brain here? Black Americans have married and > interbred for as long as 400 years, so the traces of any African > "ethnic groups" were long ago obliterated. The article is talking about mtDNA, which is inherited, without significant change, in the strict maternal line. Intermixture is irrelevant. If we were talking about the rest of the genome (leaving the Y chromosome aside, which is inherited in the strict paternal line), your point would be well taken. However, all of the ancestry tracing services use either the mtDNA or the Y chromosome, which is what the author of the article is complaining about. John Roth > > Is there some deadness of brain here? Black Americans have married and > > interbred for as long as 400 years, so the traces of any African [quoted text clipped - 3 lines] > significant change, in the strict maternal line. Intermixture is > irrelevant. Of course it is! > If we were talking about the rest of the genome (leaving the > Y chromosome aside, which is inherited in the strict paternal > line), your point would be well taken. However, all of the > ancestry tracing services use either the mtDNA or the Y > chromosome, which is what the author of the article is complaining > about. Imbecilic. What if your maternal ancestors came from five different "ethnic groups"? > > > Is there some deadness of brain here? Black Americans have married and > > > interbred for as long as 400 years, so the traces of any African [quoted text clipped - 15 lines] > Imbecilic. What if your maternal ancestors came from five different > "ethnic groups"? What if they didn't? > > > > Is there some deadness of brain here? Black Americans have married and > > > > interbred for as long as 400 years, so the traces of any African [quoted text clipped - 17 lines] > > What if they didn't? They did. > > > > > Is there some deadness of brain here? Black Americans have married and > > > > > interbred for as long as 400 years, so the traces of any African [quoted text clipped - 19 lines] > > They did. Now let's see you prove it. > > > > > > Is there some deadness of brain here? Black Americans have married and > > > > > > interbred for as long as 400 years, so the traces of any African [quoted text clipped - 21 lines] > > Now let's see you prove it. Read and learn: http://en.wikipedia.org/wiki/African_slave_trade > > > > > > > Is there some deadness of brain here? Black Americans have married and > > > > > > > interbred for as long as 400 years, so the traces of any African [quoted text clipped - 25 lines] > > http://en.wikipedia.org/wiki/African_slave_trade UC: "interbred for as long as 400 years" Read and learn. "For as long as" is not the same as saying they all were here for 400 years. Read and learn: http://www.sciencedaily.com/releases/2006/10/061012185120.htm "A study published in the open access journal BMC Biology reveals that fewer than 10% of African American mitochondrial DNA sequences analysed can be matched to mitochondrial DNA from one single African ethnic group." So even here there is an admission of 10%. But the problem is, once again, a secondary source doing the reporting. From what I can see, there may be a wooden man argument in the statement "one single African ethnic group"? How many of these companies are actually claiming that? One is claiming ancestry only for a "region" which is not the same as saying "one ethnic group" Buyer beware. >> > > > > > Is there some deadness of brain here? Black Americans have >> > > > > > married and [quoted text clipped - 28 lines] > > http://en.wikipedia.org/wiki/African_slave_trade Most North American slaves came from west Africa North of the Congo. You could cover the region on a map with your tumb. > You could cover the region on a map with your tumb. Wouldn't that rather depend on the scale of the map and the size of your "tumb"? 8-) > Most North American slaves came from west Africa North of the Congo. This wouldn't much relevance if an individual's mtDNA was inherited from the rare slave who was originally from Cape Town or Zanzibar. And there does seem to be some confusion in the minds of some in this thread about the inheritance of mitochondrial DNA. Henry Bartlett >> You could cover the region on a map with your tumb. > [quoted text clipped - 5 lines] > This wouldn't much relevance if an individual's mtDNA was inherited > from the rare slave who was originally from Cape Town or Zanzibar. or from someone much farther north or even a Native American. > And there does seem to be some confusion in the minds of some in this > thread about the inheritance of mitochondrial DNA. > > Henry Bartlett >>>Is there some deadness of brain here? Black Americans have married and >>>interbred for as long as 400 years, so the traces of any African [quoted text clipped - 15 lines] > Imbecilic. What if your maternal ancestors came from five different > "ethnic groups"? Well, someone may be imbecilic, though I prefer to be more charitable and just consider you ignorant. That, at least, can be repaired. Your maternal ancestors, meaning your ancestors in the strictly maternal line (mother's mother's mother's mother....etc.) can come only from one tribe, since in each generation there's only one of them. You get your mitochondria from this individual only. Your father's mother doesn't count. Your mother's mother's father's mother doesn't count. And so on. So there is no "intermixture" of mitochondria in individuals. There is in populations, which is why many different haplotypes are found in the same population. And that's why a mitochondrion can't be traced to a particular tribe: that haplotype is found in many different tribes. All of this has to do with Africa, not Europe or America. Unless your maternal ancestor didn't come from Africa, which is always possible. > > > Is there some deadness of brain here? Black Americans have married and > > > interbred for as long as 400 years, so the traces of any African [quoted text clipped - 15 lines] > Imbecilic. What if your maternal ancestors came from five different > "ethnic groups"? "Strict maternal" means mother's mother's mother all the way back. No males allowed. It's a totally linear regression. mtDNA does not mix. John Roth >> > > Is there some deadness of brain here? Black Americans have married >> > > and [quoted text clipped - 22 lines] > > John Roth Of course you can have the same kinds of studies done on the Y chromosome and then start looking for genetic markers on the X chromosomes if you have the money. Rots of ruck. >> > Is there some deadness of brain here? Black Americans have married and >> > interbred for as long as 400 years, so the traces of any African [quoted text clipped - 5 lines] > > Of course it is! >> If we were talking about the rest of the genome (leaving the >> Y chromosome aside, which is inherited in the strict paternal [quoted text clipped - 5 lines] > Imbecilic. What if your maternal ancestors came from five different > "ethnic groups"? With luck you will know the source of one of them. The source of the direct line of females that led to you. You won't know jack about anybody else. >> Few Clues About African Ancestry To Be Found In Mitochondrial DNA >> Mitochondrial DNA may not hold the key to your origins after all. [quoted text clipped - 99 lines] > interbred for as long as 400 years, so the traces of any African > "ethnic groups" were long ago obliterated. On the mt DNA it's a straight line on the female side. All other data is missed. In other words, "Who's your mama?" is the only question that can be asked and answered. Under the circumstances mixing in the New World doesn't mean squat as long as the mt DNA in the person can be localized to some specific part of Africa as the source. Of course that may be absolutely the only thing the person inherited from that ancestor. >>>Few Clues About African Ancestry To Be Found In Mitochondrial DNA >>>Mitochondrial DNA may not hold the key to your origins after all. [quoted text clipped - 106 lines] > specific part of Africa as the source. Of course that may be absolutely the > only thing the person inherited from that ancestor. The real problem with this is that human populations mix too much for there to be many of what are called "private alleles". Very few haplotypes are found only in a single ethnic group. They may be found in different frequencies in different ethnics groups, but at most that would give you a probability distribution, stating your chances of having come from this group or that one. If the allele is broadly distributed, that list would be a long one and the chance for each individual ethnic group would be low. Also, a proper estimate of the frequencies in different groups would require large samples of those groups, which mostly hasn't been done. That should be obvious, since many of the haplotypes apparently have never shown up in the sample at all. >> > On the mt DNA it's a straight line on the female side. All other data is > > missed. In other words, "Who's your mama?" is the only question that can be [quoted text clipped - 16 lines] > That should be obvious, since many of the haplotypes apparently have > never shown up in the sample at all. That's what I thought all along. >>>>On the mt DNA it's a straight line on the female side. All other data is >>> [quoted text clipped - 19 lines] > > That's what I thought all along. Of course you did. > >>>>On the mt DNA it's a straight line on the female side. All other data is > >>> [quoted text clipped - 21 lines] > > > Of course you did. What I meant was that this so-called "ethnic group" was sure to have a very herterogeneous genetic background. >>>>>>On the mt DNA it's a straight line on the female side. All other data is >>>>> [quoted text clipped - 24 lines] > What I meant was that this so-called "ethnic group" was sure to have a > very herterogeneous genetic background. As do all ethnic groups. So either you have to reject the term altogether for all groups, or you have to accept the term and forget about genetic homogeneity as a criterion. Either way, I don't see why you single out this one for scorn. > >>>>>>On the mt DNA it's a straight line on the female side. All other data is > >>>>> [quoted text clipped - 29 lines] > about genetic homogeneity as a criterion. Either way, I don't see why > you single out this one for scorn. The whole idea was idiotic. I thought I made that clear from the beginning. One of the few groups with a high degree of genetic similarity was ancient Egypt. Because the crown was to be kept in the 'family' as much as possible, sisters, half-sisters, nieces, and aunts often belonged to Pharoh's harem. The result was a highly inbred group. > As do all ethnic groups. So either you have to reject the term > altogether for all groups, or you have to accept the term and forget > about genetic homogeneity as a criterion. Either way, I don't see why > you single out this one for scorn. Most people scorn what they do not understand. >> >>>>On the mt DNA it's a straight line on the female side. All other data >> >>>>is >> Of course you did. > > What I meant was that this so-called "ethnic group" was sure to have a > very herterogeneous genetic background. Is it because of the maternal nature of the issue that the genetic background is herterogenous? |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.