Human Origins and Ancestry

Nearly 20 years ago, scientists developed techniques for extracting small amounts of DNA from ancient samples, like bones or fur or even soil, and used very sensitive methods for sequencing the extracted DNA [see DNA Sequencing]. Genomic studies like these have allowed us to examine human genomes from around 500,000 years ago when our ancestors (the species Homo sapiens) were diverging from other similar species, such as Homo neanderthalensis or Neanderthals.

So far, we have learned that Neanderthals took a different path than humans in their migrations around the world, but there are still traces of Neanderthal DNA sequences in our genomes today. These small stretches of DNA may influence traits that have helped people survive in some way, making it more likely to then be passed on to their children. For example, a 2017 study found that some Europeans still carry Neanderthal-like sequences that influence their circadian rhythms, making them more likely to be a morning person or a "night owl." In contrast, some DNA variants might have just happened in one population and not another. The same study found variations in the MC1R gene that lead to red hair were extremely rare or nonexistent in Neanderthals, so that trait seems to be human-specific. As we find better ways to isolate DNA from ancient remains and improve our DNA sequencing technologies, we will learn more about our species' history.

As we learn more about genomic variation in specific populations and groups, more robust tests are being developed to help you decipher your ancestral origins. But, before you take one, you need to be aware that the results of these tests may alter your perception of your family history and even of yourself. The DNA Discussion Project, started by West Chester University professors Drs. Anita Foeman and Bessie Lawton, aims to encourage greater understanding of the science of genomics, the social construct of race, and the perception of ethnicity. For example, as Drs. Sarah Tishkoff and Carlos Bustamante's research groups showed in 2010, an African American individual in the United States has, on average, about 75-80 percent West African ancestry and about 20-25 percent European ancestry. Students at West Chester shared that while they had always been told that their family had Native American ancestry, the DNA tests revealed this was not the case.

With such ancestry testing, some people have discovered that their ancestral origin is not what they thought, while others have found that close relatives are not who they thought. Some adopted children have used DNA tests to track down their birth parents, or to find previously unknown siblings. Meanwhile, some studies report that, depending on the country, anywhere between 1 percent and 10 percent of children are raised thinking that someone is their biological father when, in fact, that person is not. Ancestry testing can lead to delicate and complex situations, so it is important to think about the potential consequences before using such tests.