What is race?
Race is complex, and in general usage, is both a cultural and biological feature of a person or group of people. Given the fact that physical differences between populations are often accompanied by cultural differences, it has been difficult to separate these two elements. Over the past few decades there has been a movement in several fields of science to oversimplify the issue declaring that race is â€śmerely a social constructâ€?. While, indeed this may often be true, depending on what aspect of variation between people one is considering, it is also false for many particular instances of differences between the populations of the world. One clear example of a biological difference is skin color. Culture or environment has almost no effect on the level of pigmentation in a person's skin. Yet there are dramatic differences across populations. Pigmentation is, however, only skin deep and really quite simple in light of the complex environments in which we all live and how these affect our individual and group quality of life.
It is clear that the human species is relatively young. As a species, we most likely originated in east Africa 100,000 years ago, and diverged as groups to settle the globe. During these migrations, and in the time since, there has been some degree of independent evolution of the populations that settled the various continents of the world. The simplest evidence of this evolution can be seen in the differences in allele frequencies at genetic markers. Generally, we see that alleles found in one population are also found in all populations and the alleles that are the most common in one are also common in others. These similarities between populations highlight the recent common origin of all populations. However, there are examples of genetic markers which are different between populations and it is these markers, called Ancestry Informative Markers (AIMs), which can be used to estimate the Ancestral origins of a person or population.
What is BioGeographical Ancestry (BGA)?
BioGeographical Ancestry (BGA) is the term given to the biological or genetic component of race. BGA is a simple and objective description of the Ancestral origins of a person, in terms of the major population groups. (e.g. Native American, East Asian, Indo-European, sub-Saharan African, etc.) BGA estimates are able to represent the mixed nature of many people and populations today. In the US, as in many other countries across the globe, there has been extensive mixing among populations that had initially been separate. In the fields of human genetics and anthropology, this mixing is referred to as admixture. BGA estimates can also be understood as individual admixture proportions, which take the form of a series of percentages that add to 100%. For example, a person in question may be found to have: 75% Indo-European; 15% African; 10% Native American ancestry, or they may be found to have 100% Indo-European ancestry.
How is BioGeographical Ancestry estimated?
The test uses an especially selected panel of Ancestry Informative Markers (AIMs) that have been characterized in a large number of well-defined population samples. These markers are selected on the bases of showing substantial differences in frequency between population groups and, as such, can tell us about the origins of a particular person whose ancestry is unknown. For example, the Duffy Null allele (FY*0) is very common (approaching fixation or an allele frequency of 100%) in all sub-Saharan African populations and is not found outside of Africa. Thus, a person with this allele is very likely to have some level of African ancestry. After the analysis of these AIMs, in a sample of a person's DNA, the likelihood (or probability) that a person is derived from any of the parental populations and any of the possible mixes of parental populations is calculated. The population (or combination of populations) where the likelihood is the highest is then taken to be the best estimate of the ancestral proportions of the person. Confidence intervals on these point estimates of ancestral proportions are also being calculated.
How can BGA estimates be used?
Understanding health disparities. Are there genetic contributions to the higher rates of hypertension and diabetes in African Americans or the higher rates of dementia in European Americans? If not, then what are the cultural or environmental differences that underlie the prevailing differences? Studies of these and other diseases require independent, objective measures of BioGeographical Ancestry (BGA).
Estimates of BGA can help reconnect individuals separated by adoption, or some other event, with their ancestral populations.
Even if a person is not particularly motivated to reconnect with ancestors, he or she can uncover the past of their family either to verify family legends or to search for forgotten roots.
In the near future, we hope to allow customers to compare their ancestral proportions to others in their family, town, city, or state who have chosen to participate. Because it is based on DNA, and unlike the census, this new tool will provide the most accurate demographics data that is possible. We will call this our â€śpersonal demographicsâ€? tool.
What is the medical significance of BGA estimates?
The medical significance of BGA estimate is negligible. Although some diseases are found at different frequencies in populations across the globe, hardly any are restricted to one group. The usefulness of BGA estimates, in biomedical research, comes from epidemiological analyses where many individuals are analyzed together to make very general statements about differences in risk. Even though these results can be very significant, they have almost no meaning regarding the level of risk for any one person in the population.
How is BGA analysis different from mtDNA and Y-chromosomal ancestry analysis?
There are several commercially available tests of mtDNA and Y-chromosomal markers, which have been promoted as a means of learning oneâ€™s ancestral origins. Although these tests could provide information regarding the provenance of some of a personâ€™s ancestors, they are very limited. For example, one generation ago a person has two ancestors, one mother and one father; five generations ago, a person has 32 ancestors; while 10 generations ago, a person has 1024 ancestors. Ten generations is roughly 250 years and within the time frame of genealogical interest, especially when we are considering the settlement of North America, because they only look at two (2) chromosomes. Y-chromosomal analysis and mtDNA analysis each could only provide information on a very small proportion of a personâ€™s ancestors. Our test relies on sequences throughout your genome, so we can say more about a greater number of your ancestors.
Can BGA provide more specific information about ancestry?
The test is specifically designed to provide information on the proportions on ancestry on the continental level. In other words, this test allowed us to uncover the levels of Native American, European, and African ancestry, as three component groups. The current BGA test is expanded to provide information on the proportions of ancestry on the continental level for most continents, Native American, Indo-European (which includes European, Middle Eastern and South Asian groups such as Indians), African, but we distinguish ancestries within Asia and the Pacific Rim by adding East Asian, (which includes the Pacific Islanders) as an additional group. Since there will also be interest in defining the levels of ancestry within continents (such as distinguishing Japanese from Chinese, or Northern European from Middle Eastern), we are in the process of developing a new series of Ancestry Informative Markers that will provide more insight into where within a particular continent a personsâ€™ ancestors were most likely derived.
How can I confirm the significance of a low percentage of admixture, such as 4% Native American or 3% African?
There are two ways for you to confirm the value of this estimate: You may have access to historical records or other provenance that leads you to confirm or refute the admixture. For example, if your records suggest that you have a grandparent of East Asian heritage and you register with the test as of 5% East Asian, the two observations combined make a stronger case for East Asian ancestry than either on their own.
You can obtain the admixture proportions for your father and mother. Letâ€™s say you register with 4% African and you want to know whether this 4% is in error or is accurate. You obtain the admixture proportions from your parents and each is 100% IndoEuropean. Chances are the 4% was a result of genotyping error. However, if your mother was 15% African and your father was 100% IndoEuropean, your non-zero percentage of African is likely to be an accurate indicator of African ancestry. This is similar to option A), where you are relying on two different sources of information to help you hone in on the most accurate answer possible. Virtually every test we have performed on family trees has confirmed these types of low levels. For example if a person registers with about 11% Native American, and his Father registers with about 20%, his mother about 8% and his sister about 16% Native American. Given the knowledge from his mother, father and sister, the 11% takes on a new level of significance.
I think I have American Indian heritage, but my test results show that I am 100% Indo European.
There are two possibilities, and the first possibility is one that many people do not like to hear. We donâ€™t mean to offend, but it is a possibility that your suspicion is unfounded. If you are certain that this is not the case, the second possibility is that one of your distant ancestors was indeed American Indian but their genetic contribution to your composition has been diluted over the generations. This is a function of the genetic law of independent assortment and probability, and it depends on how admixed and how distant an ancestor the person is. What your results show is that, using our pan-genome test, there is no evidence of Native American ancestry in your DNA. In the future, it may be possible (with more sensitive and expensive tests) to detect your very dilute Native American ancestry.
I think I have American Indian heritage, but my test results show more East Asian than Native American admixture. Am I wrong or is the test wrong?
Neither â€“ your results are probably reflective of one way this test will help reshape notions of our common history. The result is certainly not an indication that the test is inaccurate. Using our test, most individuals suspecting minority (<50%) American Indian heritage confirm with Native American admixture. Likewise, the test results for each of several hundred individuals of known minority (<50%) African, East Asian or Hispanic ancestry have confirmed with the appropriate admixture. However, about 10% of the individuals who believe they have American Indian register as having East Asian as well as Native American ancestry. Even more surprising, some register with East Asian ancestry but no Native American ancestry at all! This result has stirred something of a controversy.
If you are reasonably certain the ancestor was not him/herself admixed and was recent in your family tree, there are two other possibilities. Some of the cases we have processed are probably explained by Aleut heritage and others are probably explained by admixture that occurred on the North American continent prior to European colonization.
Aleuts were the latest to arrive across the Bering straight and physically, they resemble East Asians more than other Native American peoples. Our test is enriched for markers that have changed in frequency as the human species migrated to colonize the planet, and there are an adequate number that distinguish East Asian from Native Americans as evidenced by the fact that we detect only Native American admixture in Hispanics and most American Indians. However, what if Aleuts arrived by boat or over ice after the disappearance of the land bridge? Would not the molecular distance between Aleuts and East Asians be lower than between Aleuts and other Native Americans? This is a distinct possibility, and since a test such as ours has never existed before, our results may be teaching us something about the anthropology of the Aleut group.
The remainder of the cases may reflect significant and recent East Asian admixture with Native Americans prior to European colonization. Although highly speculative, this is a very interesting possibility because several recent publications have propounded the idea that East Asians were the first to â€śdiscoverâ€? North America based on archaeological data (â€ś1421: The Year China Discovered America by Natalie Danford, William Morrow & Co; January 7, 2003). Furthermore, Asian and Native American ancestries are evident in Russians and other Europeans (Science Magazine â€śGenetic Structure of Human Populationsâ€?, fig. 1 k=6 references that Russians and the Adygei both have more non-European ancestry, primarily East Asian and Native American, in the first figure and then more Central Asian in the second figure). This idea is controversial, but if this is true, it may explain your result to a certain extent. Even so, we simply do not know yet the verity of this, which tribes harbor East Asian admixture, or even whether there is a tribe-to-tribe difference at all. As we learn more, weâ€™ll update this FAQ list
I thought I was purely of Scandinavian origin, but my results show minor East Asian admixture. How is this result possible?
Many individuals reporting pure Scandinavian ancestry register with detectible East Asian admixture as well. This result may obtain through contribution of the Lapps, indigenous Scandinavians who share physical features, culture and common history with Northern Asian populations. Because the tests is the first such test ever developed to query all of the human DNA, these results represent original interpretations of the structure inherent to modern day populations and may have exciting implications for our understanding of our anthropological history of the Scandinavian region. If your results show significant East Asian admixture (greater than 5%), you should rest assured that at the level of DNA you share some greater affiliation with East Asians. Even though we cannot go back into time and prove exactly how this affiliation came to be, the history of the Scandinavian region gives us an important clue. One excellent example of a genetic study showing that a particular Scandinavian population has East Asian ancestry, was carried out by Rick Kittles and collaborators on a several sample of Finish from different regions of Finland (Kittles et al. 2000).
Kittles RA, Perola M, Peltonen L, Bergen AW, Aragon RA, Virkkunen M, Linnoila M, Goldman D, Long JC. (1998) Dual origins of Finns revealed by Y chromosome haplotype variation. Am J Hum Genet 62:1171-1179.