While documents can easily be foundt tell you who your great-aunt is, DNA testing provides a broader view of ancestry and traces a family's migration patterns across continents and centuries.
A scanned transcript of the results of a DNA test on Peggy Spatz announced that 2.7 percent of her genetic blueprint was handed down by Neanderthal relatives some 50,000 years ago. So she's part Neanderthal, and scientists say so is everyone else who has ancestors in Europe and East Asia. Her husband, George, carries a slightly higher proportion of Neanderthal DNA, according to the results of his test.
Testing has become so widespread that DNA kits have become a popular gift for amateur genealogists. The number of participants is steadily increasing: National Geographic claims that more than 600,000 people have submitted DNA to the global Genographic Project's database, while the organization 23andMe claims to have 500,000 people in its archives. The more people who are swabbed, the larger the genetic database becomes and the more information becomes available.
«It's just cool to have information about genetics,» says Andrew Reams, geneticist and assistant biology professor at California State University, Sacramento. «Most people don't know anything about the DNA in their cells. These tests tell you something unique about yourself. «
At the cellular level, our biological history lives in the human DNA. Over the past two decades, the technology behind the sequencing of the human genome has become more and more specialized and also reduced in price. Scientific research that was once laborious, expensive and therefore limited to a few specific studies of human diseases has now grown to include the widespread genetic sequencing of humans, plants, animals and microbes lurking in the ocean and soil. As a result, a number of companies now offer DNA kits ranging in price from US$ 99 to US$ 250.
From fossil finds, paleontologists have long known that the earliest human ancestors lived in Africa. Then, more than 60,000 years ago, different groups began to migrate into the Middle East and India, and a little later across the Mediterranean and into Europe - and even later into Central Asia.
Along the way, these earliest humans mated with Neanderthals. Further research now shows that the DNA of an average person carries up to four percent of the genetic sequences that coincide with those found in Neanderthal fossils. While Saharan Africans were long thought to be exempt from Neanderthal influence, new research has now found genetic evidence of Neanderthals even among modern southern African tribes, suggesting a return migration about 3,000 years ago.
Genetic scientists such as Dr. Jonathan Eisen, a microbiologist at the UC Davis Genome Center, tend to dismiss the news of Neanderthals in the human gene as pure marketing - for science, this is nothing new. «Obviously it's fun to document parts of your DNA from a Neanderthal fossil, but there's nothing surprising about it.»
Jim Rader, a retired teacher and self-taught genetic «hobby genealogist» - as he puts it - teaches other genealogists about DNA testing. He completely rejects the commercial DNA tests as an estimate of people's Neanderthal genes. He believes that the percentage of the Neanderthal gene is far too high to be realistic.
Last November, the US Food and Drug Administration ordered 23andMe to stop selling the DNA testing service because it provided consumers with a list of possible disease risks. They were concerned about how consumers would use this information. However, the company continues to market its DNA testing services to genealogists.
