I have posted a number of notes in the past about 23andMe, a company that does genetic testing of people who submit a sample of mucosal cells for DNA analysis (see, for example: 23andMe Builds Online Sarcoma Research Community; The Dispute between the FDA and 23andMe; What's Really Going On?; Pfizer and 23andMe Collaborate to Study Inflammatory Bowel Disease). The company is now running correlation studies of their DNA database with the self-declared ethnic groups of some of its customers (see: White? Black? A Murky Distinction Grows Still Murkier). Here's an excerpt from the article:
Over time...[23andMe] has built a database that not only includes DNA, but also such details as a participant’s birthplace and the ethnic group with which he or she identifies.....Recently they used their program to calculate what percentage of each subject’s genomes was inherited from European, African or Native American forebears....On average, the scientists found, people who identified as African-American had genes that were only 73.2 percent African. European genes accounted for 24 percent of their DNA, while .8 percent came from Native Americans. Latinos, on the other hand, had genes that were on average 65.1 percent European, 18 percent Native American, and 6.2 percent African. The researchers found that European-Americans had genomes that were on average 98.6 percent European, .19 percent African, and .18 Native American....Based on their sample, the researchers estimated that over six million European-Americans have some African ancestry. As many as five million have genomes that are at least 1 percent Native American in origin. One in five African-Americans, too, has Native American roots....
Most Americans with less than 28 percent African-American ancestry say they are white, the researchers found. Above that threshold, people tended to describe themselves as African-American. ....African-Americans in Georgia and South Carolina have the highest average percentage of African ancestry among African-Americans in the United States.....Latinos in the Southwest had high levels of Native American DNA, they found, while Latinos in the Southeast had high levels of African DNA....In Oklahoma, the researchers estimated, 14 percent of African-Americans have genomes that are at least 2 percent Native American. This high percentage is probably due to the unique history of the state. Some Native American tribes in the South, such as the Cherokee and Choctaw, kept African slaves. When they were expelled to Oklahoma in the 1830s, they brought the slaves with them. In some tribes, Native Americans and African slaves intermarried, and their descendants continue to live in Oklahoma today.
The NYT article quoted above points out that the analysis performed on the 23andMe database is subject to sample bias because it is limited to people who choose to submit DNA samples, perhaps because they are interested in their own genealogy and were willing to pay the fee. Moreover, the ethnic identity of their customers is self-declared. However, I found the article fascinating. I was not personally aware that Native Americans kept African slaves. Here's a brief summary of this practice from a Wikipedia article (see: Slavery among Native Americans in the United States):
The Cherokee was the tribe that held the most slaves. In 1809, they held nearly 600 enslaved blacks. This number increased to almost 1,600 in 1835, and to around 4,000 by 1860, after they had removed to Indian Territory.....The proportion of Cherokee families who owned slaves did not exceed ten percent, and was comparable to the percentage among white families across the South, where a slaveholding elite owned most of the laborers. In the 1835 census, only eight percent of Cherokee households contained slaves, and only three Cherokee owned more than 50 slaves. Joseph Vann had the most, owning 110 like other major planters. Of the Cherokee who owned slaves, 83 percent held fewer than 10 slaves. Of the slave-owning families, 78 percent claimed some white ancestry.
Many of our ideas about race are going to be altered, or perhaps even reinforced, by genetic studies with this article as only the opening salvo. People have very strong opinions about 23andMe, both pro and con. I find it a very interesting company and will continue to cover it when the occasion arises.