No 'lost tribes' or aliens: what an­cient DNA re­veals about Amer­i­can pre­his­tory

The Guardian Australia - - Science - Jen­nifer Raff

Ge­net­ics re­search has trans­formed our un­der­stand­ing of hu­man his­tory, par­tic­u­larly in the Amer­i­cas. The fo­cus of the ma­jor­ity of high pro­file an­cient DNA pa­pers in re­cent years has been on ad­dress­ing early events in the ini­tial peo­pling of the Amer­i­cas. This re­search has pro­vided de­tails of this early his­tory that we couldn’t ac­cess though the arche­o­log­i­cal record.

Col­lec­tively, ge­net­ics stud­ies have shown us that the indige­nous in­hab­i­tants of the Amer­i­cas are de­scended from a group that di­verged from its Siberian an­ces­tors be­gin­ning some­time around 23,000 years be­fore present and re­mained iso­lated in Beringia (the re­gion of land that once con­nected Siberia and North Amer­ica) for an ex­tended pe­riod of time. When the glaciers cov­er­ing North Amer­ica melted enough to make the Pa­cific coast nav­i­ga­ble, south­ward travel be­came pos­si­ble, and pat­terned ge­netic di­ver­sity across North and South Amer­ica re­flects these early move­ments.

Re­cent an­cient DNA stud­ies in­di­cate that ap­prox­i­mately 13,000 years ago, two clades (ge­netic groups) of peo­ples emerged; one ex­clu­sively con­sist­ing of north­ern Na­tive Amer­i­cans, and one con­sist­ing of peo­ples from North, Cen­tral, and South Amer­ica, in­clud­ing the 12,800 year old Anz­ick child from a Clo­vis burial site in Mon­tana. All ge­net­ics re­search to date has af­firmed the shared an­ces­try of all an­cient and con­tem­po­rary indige­nous peo­ples of the Amer­i­cas, and re­futed sto­ries about the pres­ence of “lost tribes”, an­cient Euro­peans, and (I can’t be­lieve that I ac­tu­ally have to say this) an­cient aliens.

Events that oc­curred af­ter peo­ple first en­tered the Amer­i­cas – how they set­tled in dif­fer­ent parts of the con­ti­nents, adapted to lo­cal en­vi­ron­ments, in­ter­acted with each other, and were af­fected by Euro­pean colo­nial­ism – have re­ceived some­what less at­ten­tion in the press, but as can be seen in the links above, there have been some very sig­nif­i­cant re­search pa­pers pub­lished on these top­ics. One such pa­per that I’ve re­cently found very in­ter­est­ing (in fact, I wrote up a short ar­ti­cle for Cur­rent Bi­ol­ogy that dis­cusses its sig­nif­i­cance), Ge­netic Dis­con­ti­nu­ity be­tween the Mar­itime Ar­chaic and Beothuk Pop­u­la­tions in New­found­land, Canada by Duggen et al. (2017), ex­plores the ge­netic di­ver­sity within three dif­fer­ent an­cient groups who lived in New­found­land and Labrador.

One rea­son this re­gion is of par­tic­u­lar in­ter­est is that it’s on the fur­thest north­east­ern mar­gin of North Amer­ica and so was one of the last ar­eas in the Amer­i­cas to be peo­pled. It ap­pears to have been oc­cu­pied suc­ces­sively by three cul­tur­ally dis­tinct groups be­gin­ning about 10,000 years be­fore present (YBP) in Labrador and 6,000 YBP in New­found­land: the Mar­itime Ar­chaic, the Pa­leo-Inuit (also re­ferred to as the Pa­leo-Eskimo), and the indige­nous peo­ples that Euro­peans called the Beothuk. To­day the re­gion is home to sev­eral indige­nous groups, in­clud­ing the Inuit, the Innu, the Mi’kmaq and the South­ern Inuit of Nu­natuKavut.

The mem­bers of the Mar­itime Ar­chaic tra­di­tion cre­ated the old­est known burial mounds in North

Amer­ica (dat­ing to 7,714 YBP) and sub­sisted upon coastal ma­rine re­sources. Ap­prox­i­mately 3,400 YBP they seem to have aban­doned New­found­land, either in re­sponse to the ap­pear­ance of Pa­leo-Inuit in the re­gion or be­cause of cli­mate changes. The Pa­leo-Inuit’s pres­ence on the is­land over­lapped with the peo­ples re­ferred to as the Beothuk be­gin­ning around 2000 YBP. The Beothuk en­coun­tered Euro­pean set­tlers in 1500 AD, and in re­sponse to their pres­ence grad­u­ally moved to the in­te­rior of the is­land, where their pop­u­la­tions de­clined.

Ac­cord­ing to Duggen et al: By an­a­lyz­ing mi­to­chon­drial hap­logroups (groups of closely re­lated ma­ter­nal lin­eages) present within in­di­vid­u­als from all three pop­u­la­tions, Du­gan et al. ad­dressed the ques­tion of whether they were ge­net­i­cally sim­i­lar or whether all three groups were bi­o­log­i­cally as well as cul­tur­ally dis­tinct from each other. This hap­pens to be one of the most fun­da­men­tal ques­tions that arises when study­ing the past: do cul­tural changes in the ar­chae­o­log­i­cal record of a re­gion rep­re­sent the ar­rival of new groups, or did one group of peo­ple liv­ing in the same re­gion over time adopt new cul­tural prac­tices and tech­nolo­gies from oth­ers?

In the case of New­found­land, the three groups were ge­net­i­cally dis­tinct; they do not share any ma­ter­nal hap­logroups ex­cept for hap­logroup X2a, lin­eages of which were found in both the Mar­itime Ar­chaic and Beothuk. (The pres­ence of hap­logroup X2a in North Amer­i­can pop­u­la­tions has some­times been cited as ev­i­dence for Euro­pean an­ces­try in an­cient Amer­i­cans. If you’re in­ter­ested in why I and most other ge­neti­cists spe­cial­iz­ing in Na­tive Amer­i­can pop­u­la­tions dis­agree with that, you can read about it here).

Apart from that sin­gle ex­cep­tion, the Mar­itime Ar­chaic, Pa­le­oI­nuit, and Beothuk are clearly ge­net­i­cally dis­tinc­tive from one an­other. How­ever, it’s im­por­tant to note that this study was done on mi­to­chon­drial DNA, which is ex­clu­sively ma­tri­lin­eally in­her­ited, and so we can only say that the three groups were not ma­ter­nally re­lated. While they in­di­cate that the groups are ge­net­i­cally dif­fer­ent from each other, does that mean that there was no shared an­ces­try be­tween them at all? It’s un­clear with­out look­ing at the rest of the genome whether, for ex­am­ple, there might have been any pa­ter­nal lin­eages shared be­tween the pop­u­la­tions. I hope that the au­thors of this study will fol­low up with analy­ses of com­plete genomes from these an­cient in­di­vid­u­als, as there is a great deal more to be learned by look­ing more deeply at their an­ces­try.

As this study shows, we can learn a lot about the past by char­ac­ter­iz­ing the genomes of an­cient and con­tem­po­rary peo­ples. This pa­per by Duggen et al. adds to decades of study of the genomes from an­cient and con­tem­po­rary peo­ples of the Amer­i­cas, which re­veals a nu­anced pic­ture of their com­plex and re­mark­able his­tory of evo­lu­tion, in­ter­ac­tion, and re­silience in the face of un­be­liev­able op­pres­sion.

But it’s also im­por­tant to un­der­stand what ge­net­ics can’t tell us. While writ­ing up this ar­ti­cle, I was ap­palled (although not sur­prised) that there is at least one per­sonal an­ces­try test­ing com­pany that has made the claim that they can help you de­ter­mine whether or not you are Beothuk based on your DNA.

Let’s be clear: all claims that a per­son’s tribe or indige­nous na­tion­al­ity can be de­ter­mined from their genomes are sci­en­tif­i­cally in­ac­cu­rate. First, this is be­cause there sim­ply are no cur­rently known ge­netic mark­ers that al­low us to iden­tify in­di­vid­ual tribes or na­tions; although we see ge­o­graph­i­cally pat­terned ge­netic vari­a­tion through­out the Amer­i­cas in an­cient and con­tem­po­rary pop­u­la­tions which al­lows us to dif­fer­en­ti­ate them (as done in this study), ge­netic lin­eages are not tribal or na­tion-spe­cific.

More im­por­tantly, who is or is not a mem­ber of a par­tic­u­lar com­mu­nity is de­ter­mined by indige­nous groups’ own stan­dards of be­long­ing, which are of­ten just as much about re­la­tions and com­mu­nity ties as they are about bi­o­log­i­cal de­scent. Ge­neti­cists can’t de­ter­mine who is or is not au­then­ti­cally Beothuk, Chero­kee, or any­thing else based on the per­cent­age of “Na­tive Amer­i­can DNA” they might have. (For more in­depth dis­cus­sions of the is­sues re­gard­ing ge­net­ics and Na­tive Amer­i­can iden­tity, see here and here and the read­ing be­low).

Fur­ther read­ing:

Dug­gan AT et al. 2017. Ge­netic dis­con­ti­nu­ity be­tween the Mar­itime Ar­chaic and Beothuk pop­u­la­tions in New­found­land, Canada. Cur­rent Bi­ol­ogy 27(20): 3149-3156.e11.

Ruther­ford A. 2017. A new his­tory of the first peo­ples in the Amer­i­cas.

Tall­bear K. 2013 Na­tive Amer­i­can DNA: Tribal Be­long­ing and the False Promise of Ge­netic Science.

Swim­ming Bear Mid­dle Dorset (Pa­leo-Eskimo) Cul­ture Alamek Site, Iglu­lik Re­gion, Canada. Pho­to­graph: Dal­béra, Jean-Pierre

Ice­berg Al­ley, New­found­land, Canada Pho­to­graph: Grant Faint/Getty Images

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