Researchers Use SNP Analysis to Paint Picture of an Ancient Human

Artist’s impression of Inuk based on genetic analysis
Nuka Godfredsen/Nature

Tufts of hair rescued from the permafrost in Greenland and then tucked away in a basement in Denmark for more than 20 years have given scientists their first glimpse into the genetics of an ancient human.

Eske Willerslev and Morten Rasmussen of the Centre for GeoGenetics at the Natural History Museum of Denmark and the University of Copenhagen, along with an international team of collaborators, have sequenced 80% of the genome of a man from the Saqqaq Culture who walked the earth about 4,000 years ago.  By comparing this ancient DNA sequence to what is known about the genetics of modern humans, the researchers were able to piece together a picture of what the man they call Inuk (“human” or “man” in Greenlandic) likely looked like, where his people came from, and how he’s related to modern populations.  The results were published online today in the journal Nature.

Inuk’s DNA revealed that he had type A+ blood.  He likely had brown eyes and thick, dark hair.  His skin was probably not the light color found in modern day Europeans.  Inuk’s earwax was dry and he had shovel-graded front teeth, both characteristics common in Asian and Native American populations.  Several of the genetic variants he carried suggest that he had a metabolism and body mass well-suited to cold climates. The researchers even found that Inuk’s genetics are indicative of an increased risk of baldness.

“Because we found quite a lot of hair from this guy, we presume he died quite young,” Willerslev said in a press briefing.

(Although as Harvard professor and Luxuriant Flowing Hair Club for Scientists member Steven Pinker found when analysis of his DNA also suggested a propensity for baldness, DNA is not always destiny.)

Analysis of Inuk’s Y chromosome revealed that his paternal haplogroup is Q1a, which is commonly found among Siberian and Native American populations. Previous analysis by the same research group had revealed that Inuk’s maternal haplogroup, determined by his mitochondrial DNA, is D2a1.  This same lineage is commonly found in modern-day Aleuts of the Commander Islands in the Bering Sea and the Siberian Sireniki Yuits (Asian Eskimos).

Since discovery of the remains of the Saqqaq Culture in the 1950s, there has been disagreement over how these people were related to others that crossed the Bering Strait into the New World.  By analyzing Inuk’s DNA and comparing it to modern populations, the researchers determined that the Saqqaq are most closely related to the Nganasans, Koryaks and Chukchis of Siberia.  The long-gone Saqqaqs most likely left Siberia for the New World about 5,500 years ago, independently from the ancestors of present-day Native Americans and Inuit.

Now that his team has shown that full genome sequence analysis of ancient samples is feasible, Willerslev expects that there will be an explosion of work in the field.  He says that sequencing of DNA from South American mummies could help illuminate the population history and genetic diversity of Native Americans from before the arrival of Europeans.  Willerslev also suggests that sequencing ancient human DNA could reveal when certain genetic diseases become prevalent in different populations.

Do you share genetic characteristics with Inuk?  The table below lists the SNPs the researchers used to come up with their physical description of the ancient man.  SNPs currently covered by 23andMe are linked to the Browse Raw Data feature, where Complete Edition customers can check their own genotypes.  Inuk’s genotype at each SNP is presented in the format used on the 23andMe website, which may not match the original paper.  The notes column lists 23andMe content related to each trait and/or SNP.

Trait SNP Inuk’s Genotype Notes
Blood type – Not type O* rs8176719 II This SNP is part of the ABO blood type lab health lab.
Blood type – Type A1 rs8176750 II
Brown eyes rs12913832 AA This SNP is reported on in the Eye Color Trait Report.
Brown eyes rs7495174 AG
Brown eyes rs4778241 AA
Brown eyes rs1129038 CC
Not European light skinned rs1426654 GG
Baldness rs1385699 T A different SNP is reported in the Baldness Research Report.
Baldness rs6152 G Both baldness SNPs are on the X chromosome.  Males like Inuk have only one copy.
Higher BMI rs1528133 GT
Higher BMI rs2272383 AG
Higher BMI rs2272382 CT
Higher percentage  fat mass rs5746059 AA
Dry earwax rs17822931 TT This SNP is reported on in the Earwax Type Trait Report.
Thick hair and shovel-graded teeth rs3827760 GG This SNP is reported on in the Hair Thickness Research Report.
Black hair rs16891982 CC
Cold adaptation rs1042522 GG See previous blog posts about this SNP’s relation to winter temperatures and colorectal cancer.
Cold adaptation rs13222385 AG
Cold adaptation rs751141 AA
Cold adaptation rs1800404 TT
Cold adaptation rs1426654 GG
Cold adaptation rs2570932 CC
Cold adaptation rs12946618 AA
Cold adaptation rs12946115 CC

* The genotype the study authors listed for this SNP (which was originally listed in this tabel) actually indicated that Inuk would have had type O blood.  We contacted the authors and they confirmed that this was simply a typo.  The table now reflects Inuk’s true genotype.