Scanning a printout of her ancestry results from a DNA testing company, Peggy Spatz announced that 2.7 percent of her genetic blueprint was handed down from her Neanderthal relatives some 50,000 years ago. That’s right: She’s part Neanderthal, and scientists say so is everyone else whose ancestors originated in Europe and East Asia.
Her husband, George, carries a slightly higher percentage of Neanderthal DNA, according to the results of his own DNA test.
“And I have friends who’ll say that’s not nearly as much Neanderthal as I really am,” said George Spatz, 68, a retired Pacific Gas and Electric Co. manager who lives with Peggy, 53, in suburban Sacramento.
It’s the latest twist in the search for family roots, and one that goes well beyond using census records to identify distant twigs on the family tree. Americans are swabbing their cheeks and spitting in vials to uncover their Neanderthal roots through genealogical DNA testing, which traces personal ancestry through analysis of an individual’s genetic code. While documents can tell you who your great-aunt was with ease, DNA tests provide a broad view of ancestry, tracing a family’s migration patterns through continents and centuries.
DNA testing has become so widespread among amateur genealogists that the kits proved to be a popular holiday gift item. The numbers of participants are steadily growing: National Geographic claims that more than 600,000 people have submitted DNA to its global Genographic Project database, for example, while ancestry service 23andMe claims 500,000 people in its own files. And the more people who are swabbing, the greater the size of the genetic database and the more information companies can provide.
“It’s just really cool to have information about your genetics,” said Andrew Reams, a geneticist and assistant biology professor at California State University, Sacramento. “Most people know nothing about the DNA in their cells. These tests tell you something unique about yourself.”
On a cellular level, our biological history lives in human DNA, or deoxyribonucleic acid, which carries genetic instructions in the nuclei of our cells. Over the past two decades, the technology behind the sequencing of the human genome has rapidly increased in sophistication and decreased in price. Scientific research that was once painstakingly difficult, expensive and therefore limited to a few specific studies of human diseases has grown to include the widespread genetic sequencing of humans, plants, animals and the microbes lurking in the ocean and the soil.
In turn, the field of personal DNA testing to trace ancestry and, more controversially, health information has boomed, with an array of companies offering DNA kits that typically range in price from $99 to $250. Scientists refer to this trend as genetic genealogy or, a little more dismissively, recreational genomics – but by submitting a cheek swab or small vial of saliva, consumers can learn where they came from and how their long-ago relatives migrated the earth over the millennia.
From fossil discoveries, paleontologists have long known that the earliest human ancestors lived in Africa. Various groups of those early humans began migrating more than 60,000 years ago into the Middle East and India and, slightly later, across the Mediterranean and into Europe – and later than that, into Central Asia.
Along the way, these early humans mated with Neanderthals: Genomics research shows that the DNA of the average person carries up to 4 percent of genetic sequences that coincide with those found in Neanderthal fossils. While sub-Saharan Africans – the homebodies – were long thought to be exempt from Neanderthal influence, new research has also found genetic evidence of Neanderthals among modern southern African tribes, suggesting a return migration 3,000 years ago.
Genetic scientists tend to dismiss DNA testing news about the Neanderthals swimming in the human gene pool as marketing, not science – mainly because to them it’s nothing new.
“I find that to be one of the dumbest things in all of these tests,” said Dr. Jonathan Eisen, a microbiologist with the UC Davis Genome Center. “It irks me to see people talking about that. It irks me to see scientific papers about that talked about on CNN. I guess people had something in their head that humans are pure.
“Every species in nature hybridizes with its close relatives. This is routine. From a human history point of view, it’s somewhat interesting but not remotely surprising. Yes, it’s cool to document your ancient DNA from a Neanderthal fossil, but there’s nothing surprising about it.”
‘Parlor talk, not science’
At 71, Jim Rader is a retired teacher and self-taught genetic genealogist – “a hobbyist,” as he put it – who gives classes to other genealogists on DNA testing. He rejects commercial DNA tests’ estimates of people’s Neanderthal genes altogether.
“In my opinion, it’s another marketing gimmick,” said Rader, who has submitted samples to several DNA testing companies. “The percentages are way too high to be realistic.”
He cautions further that consumers should be aware that the results provided by DNA companies are based on studies of their own participants: An individual’s genetic signature is measured only against that of other individuals who have submitted samples to the same company, not against a global population.
In Rader’s case, Family Tree DNA estimated his ethnicity several years ago as 62 percent central European – and revised that estimate in October 2013, based on an updated and more comprehensive database, to 85 percent British.
In other words, the science behind genetic genealogy is far from exact.
“These are all preliminary results,” Rader said. “They’re still figuring out. The results are good for parlor talk, not for science.”
But he’s found personally that DNA testing – specifically, testing of the Y chromosome – can play a vital role in helping genealogists.
Many companies now test only mitochondrial DNA, or DNA that’s carried on the X chromosome and passed through the maternal line. Women carry only mitochondrial DNA on their two X chromosomes, but men also carry DNA on the Y chromosome – and men who share a common paternal ancestor, even dating to generations ago, will share that matching genetic pattern.
Through scouring several centuries’ worth of documents and records, Rader has found 95,000 other people in this country with the surname Rader. But it was through testing his Y-DNA that he found distant cousins who can also trace their ancestry to an 18-year-old German immigrant named Johan Casper Rotter, who stepped off the ship Edinburgh in Philadelphia in August 1750.
“I found living males who thought they were descended from him, too, and I encouraged them to take the Y chromosome test,” said Rader. “Three of us have exactly the same Y chromosome. So we’re all descended from the same male DNA.
“Genealogy tells us that male is Johan. DNA tells us we’re related.”
‘The ultimate mystery’
Glenda Gardner Lloyd, who has traced her roots for four decades and helped found the Sacramento Genealogical Society in 1978, donated a four-generation family tree and a blood sample to help establish the Brigham Young University DNA Sequencing Center. That was more than 20 years ago. Despite her long interest in her family’s heritage, she hasn’t dabbled in genetic genealogy since then.
But her brother has. At Lloyd’s urging, she said, he had Y-DNA sequencing done to help fill in a specific blank on the Gardner genealogy chart: Who was the father of their ancestor, Henry Gardner, born in Morris County, N.J., in the 1700s?
“The results show there could have been an adoption or illegitimate child at some point in the line,” said Lloyd, 75. “There have been matches but not a single one is of the Gardner surname. What that says is that somewhere there’s a mix-up in the family.
“I think it’s fascinating. I think genealogy is the ultimate mystery, if you like detective work. You’re digging into your family’s history.”
Peggy Spatz loves uncovering that history, too: She’s pieced together her genealogy for more than 20 years. George Spatz, on the other hand, has little interest in his own family tree. Last June, when they submitted their DNA for testing with Bay Area-based 23andMe and discovered their Neanderthal roots, it was health information they were hoping to find, not more relatives.
In November, the Food and Drug Administration ordered 23andMe to stop selling its personal genome testing service, which provided consumers with a list of possible disease risks, out of concern for how consumers would use that information. The company continues marketing its ancestry DNA testing services.
Customers such as the Spatzes still have online access to their health results. What they learned, they said, was mostly the family health information they already knew.
Besides, said Peggy Spatz, “The test said I’m supposed to have blue eyes, but I have green eyes. I decided not to be freaked out about the test. I realized, ‘Take this with a grain of salt.’ It’s not perfect science. It’s new science.”
“Some pieces were dead-on, but it’s not infallible,” said her husband. “The test said I’m supposed to have curly hair.”
Instead, he’s bald, the result of inheriting the male-pattern baldness gene.