Down to Earth With: Molecular biologist Sarah L. Anzick

by Sara E. Pratt
Friday, October 3, 2014

In May 1968, when Sarah L. Anzick was 2 years old, the 12,600-year-old remains of a male toddler were discovered at the base of a bluff on her family’s ranch near Wilsall, Mont. The Anzick infant — one of just a handful of ancient skeletons to have been found in North America and the only known Clovis burial site — had been carefully buried with more than 100 stone and bone tools.

Anzick went on to become a molecular biologist at the National Institutes of Health (NIH). Today, she works in the genomics unit at NIH’s Rocky Mountain Laboratories in Hamilton, Mont., where she brings genetics to bear on the study of allergies, immunology and infectious diseases. Earlier in her career, she participated in the Human Genome Project, the 14-year endeavor to map all 3.2 billion base pairs in the human genome completed in 2000, which launched a revolution in genetics. Since then, advances in technology have made it possible to map a genome in just a few days — and to extract and analyze ancient DNA.

Over the years, Anzick had often wondered what the infant’s DNA might reveal about its origins and those of the first Americans. Recently, she was able to answer that question. Last February, a team of scientists including Anzick* published a DNA analysis of the infant’s genome in Nature. The study showed that the child was most closely related to modern populations of Native Americans from Central and South America, and that he descended from a population that migrated from Asia, not Europe, as previous theories had suggested.

Previous discoveries of Paleoindian remains have been controversial because of the competing interests of paleoanthropologists who want to study the remains as artifacts and many Native American tribes who believe such remains are sacred and should not be disturbed or studied, but rather reburied. Some tribes are against genome sequencing of living members as well.

In June, after 46 years above ground, the Anzick infant’s remains were reburied in a ceremony involving both scientists and representatives from several Native American tribes.

Anzick spoke with EARTH’s Sara E. Pratt about the unique and sometimes controversial issues involved in studying ancient remains as well as the implications of the study in seeking to answer one of the most pressing questions in paleoanthropology: Who were the first Americans?

[*Anzick undertook the research privately as a representative of her family and no federal agency or funding was involved in the study.]

SEP: Growing up, how did you become interested in science and nature? Who and what inspired you?

SLA: My father, a veterinarian, was my inspiration. I did well in the sciences and I wanted to follow in his footsteps and go to veterinary or medical school. And, of course, being raised in Montana, I was always outdoors, camping and fishing. In fact, nearby the Anzick site was where I caught my first fish.

When I was in college, I did a summer internship at Los Alamos National Laboratory in New Mexico, which was a pivotal point. I had a great mentor there who inspired me to go into research and I became interested in molecular biology and genetics. I went back to [the lab] each summer in college, and then was recruited to work there after college on the mapping of human chromosomes 16 and 21, part of the Human Genome Project.

SEP: What do you recall about the discovery of the Anzick infant?

SLA: Well, nothing of the discovery itself, but I was told the story. It was found by construction workers whom my father had permitted to excavate fill from our land for a local school building project. They came back later that night with their wives and collected all the artifacts and bones. The tools were stacked neatly in a meter-square vault on top of the skeletal remains, which were just a few skull fragments, some ribs and a clavicle. They took the artifacts home and washed them, rinsing much of the red ochre that coated the artifacts down the drain. A few days later, the workers told my father what they had found and he called an archaeologist at the University of Montana, who determined the skeleton and artifacts were Clovis. The human remains stayed with the archaeologist and the artifacts were split between my family and the workers.

Back then, the focus was mainly on the stone artifacts that came from the site. My parents were provided beautiful glass display cases for them. The Smithsonian made replicas of the artifacts in 1974 and photographs of some of the materials appeared on the cover of National Geographic in September 1979. Sometimes complete strangers would knock on the door and ask to see the artifacts and my parents would invite them in. The artifacts were always just around, a part of my childhood, a part of our family. They’ve since been loaned to the Montana Historical Society in Helena, and the other two owners have loaned their artifacts as well, so the entire collection is together again and on display there.

SEP: How did you become involved with the genetic analysis of the Anzick infant?

SLA: In 1999, when the son of the archaeologist returned the human remains to my family, I felt compelled to see if we could extract 13,000-year-old DNA to learn more about this ancient child. But this was during the heated days of Kennewick Man [the 9,300-year-old remains found in Washington state in 1996 that resulted in a protracted legal battle among the federal government, native tribes and paleoanthropologists]. So I came out to Montana and talked to the tribes that were nearest to the site, even though it was unlikely these were the same tribes that were here 13,000 years ago. But it’s a really hard and challenging problem. One tribe said they would be OK with analyzing anything over 3,000 years old because their oral traditions only went back that far and they were curious to know what we would find. But another tribe was adamant that the remains not be studied. Not reaching a consensus between tribes made it clear it was going to be controversial. Also, the technology wasn’t quite there yet. So, I stepped back for a time and just respectfully stored the remains.

Then, a few years ago, Mike Waters [at the Center for the Study of the First Americans at Texas A&M University] contacted me and asked to do carbon dating of the nonhuman artifacts and said he and Eske Willerslev [at the Centre for GeoGenetics at the Natural History Museum of Denmark and University of Copenhagen] were interested in trying to obtain DNA from the Anzick remains. At that time, I told them I wanted to be involved, not only because I do genetic research and it was something that I had also wanted to do, but also because I could maintain control over the remains and ensure that they were treated with respect.

SEP: What did you and your co-authors find and how does it change what we know about the first Americans?

SLA: I was involved in the initial mitochondrial genotyping, which came back as one of the five Native American genetic haplotypes [a set of gene variations inherited together], but the subgroup haplotype identified in Anzick is rare, present in only 1 to 2 percent of living populations. The mitochondrial haplotype indicated that the remains were most closely related to the Mayans. However, mitochondrial DNA only provides information on the maternal inheritance and is not informative in trying to nail down complete heredity.

It wasn’t until last summer that we were able to obtain the full genomic sequence of this Clovis individual. The data were then compared to 143 modern populations worldwide, including 52 Native American populations [from South America and Canada]. The Anzick infant was more closely related to these 52 Native American populations than to any others around the world.

Then we compared it to three other ancient, previously sequenced individuals. One was a 24,000-year-old Malt’a individual that was found in Siberia [near Lake Baikal], which was also closely related to Native Americans. In addition, about a third of the Malt’a genome was closely related to Western Eurasian DNA. That’s really interesting: We have Native Americans related to Western Eurasians 24,000 years ago. So it’s not necessarily post-Columbian admixture. About a third of the Anzick boy’s genetics looks just like the Malt’a individual and the rest is Native American. But we did find that the Anzick remains are more closely related to Central and Southern Native American populations than to Northern Native American populations.

So what we think happened is that there was one founder population in the U.S., which supports what Native Americans have always said, which is, “We started here and we’ve been here forever.” Our results actually show that is correct — Native Americans were formed in the Americas.

But there was probably a deep divergence in the Americas in pre-Clovis time, in which one population went north, which is ancestral to the Canadian tribes, and one went south, which is ancestral to the South American tribes. We know that Anzick fits on the southern branch. But we have no DNA from any U.S. Native American tribes, so we don’t know where they fit on that split. We have a database of more than 1,000 genomes from populations around the world that have been fully sequenced — but no U.S. Native American genomes, which is something I’m advocating for.

SEP: As both a scientist and someone with a personal connection to the discovery of ancient remains, what are your thoughts on the issue of scientific study versus reburial? Can there be compromise?

SLA: It’s difficult because of the variety of opinions in Native American populations. The Alaskan tribes, for example, seem to be more open to research, as in the case of the On-Your-Knees cave individual, which was studied and reburied in a ceremony involving both tribal members and scientists. In Montana, one elder said he thought Anzick should be studied and not reburied because his tribe’s oral traditions were dying out and he would welcome whatever information we could discover. But others wanted the remains reburied with no study. It was very hard because I knew that whatever path I took, somebody wasn’t going to be happy.

One of the most important things we learned, however — something that needs to be remembered — is that the scientific results need to be beneficial to the tribe and they need to be shared. With efforts along those lines, and with open communication and tribal involvement, I think there can be cooperation. However, I think that scientists need to be willing to make sacrifices and compromises, like reburying the skeleton. That was a sacrifice for the scientific community because there was so much more we could have learned. But I was happy to do it.

SEP: What was the reburial ceremony like?

SLA: The burial was on June 28. More than 30 tribal members from seven tribes, including the Umatilla from Kennewick, Wash., and the Apache from Arizona, attended. A representative from each of the tribes was invited to say something or sing a song. Everyone participated, taking turns putting dirt or red ochre into the grave, which was covered in rocks and marked with a stick with feathers on it. It was a beautiful ceremony.

It’s been a long, challenging road — I feel like I aged about 13,000 years myself — but it really ended beautifully.