A paper published in Nature (online) last November (Maravall-López J, Motti JMB, et al., (2025). Eight millennia of continuity of a previously unknown lineage in Argentina. Nature. 2026 Jan;649(8097):647-656. doi: 10.1038/s41586-025-09731-3. Epub 2025 Nov 5. PMID: 41193808; PMCID: PMC12747222.) describes, like its title says, a new Native American lineage that "persisted for thousands of years with no evidence of interregional migration."
The authors studied more than 200 prehistoric genomes from central Argentina, between the Andes, the Paraná River, Patagonia and Bolivia, and Paraguay in the North. They found that the people who lived there had their own, unique lineage that lasted for millennia. They didn't live in isolation, they admixed with others. This paper is a step in the right direction towards understanding how America was peopled.
The 10,000 BP Laguna de los Pampas remains
I found the paper interesting, but what I found more interesting was the oldest specimen used in the genetic study, an individual from a tiny lake in the Argentine Pampas region (see it in Google Maps), at that time a vast open grassland. The lake is called Laguna de los Pampas (after the Historic natives, the Pampas people). It forms part of the region that the paper calls Central Southern Cone (CSC) which lies east of the Andes and spans Northwestern Argentina highlands and Mountain ranges, the pampean hills in central Argentina, the plains of the Pampas, as well as the drier western Pampa region north of the Patagonia, and west of the Paraná River. It also includes the Chaco forests and savanna or the Jungles, marshes and fluvial areas of the Paraná basin.
The authors state that "To understand how the oldest individual, Argentina_Pampas_LagunadelosPampas_10000BP (hence, LagunadelosPampas_10000BP) relates to other Early/Middle Holocene South Americans, we computed 𝑓4-statistics... These statistics reveal shared drift among LagunadelosPampas_10000BP and Argentina_Central_JesusMaria_8500BP (henceforth, JesusMaria_8500BP), the individuals from Southern Patagonia (5100-7300BP) and those from the Argentinian Pampas (7700-6800BP), with respect to both early individuals from the Central-East of Brazil (10400-6800BP) and the Central Andes (9000-8600BP)."
Then they display the relationship in the paper's Figure 2. But, surprisingly, it does not include the Laguna de los pampas 10000BP individual!
They go on to say that "We found no evidence of mixture events fitting the data significantly better, although this could be a reflection of low statistical power. LagunadelosPampas_10000BP is absent from the tree because of its ambiguous positions across well-fitting models."
So they have the oldest sample in the region, 10,000 years BP, and they couldn't fit it into their phylogenetic tree because their "well-fitting models" couldn't fit it. How well fitting are they if they can't account for this critical specimen?
They continue by saying that "All pairs of JesusMaria_8500BP, Southern Patagonia (5100-7300BP), and Argentinian Pampas (7700-6800BP) are symmetrically related to LagunadelosPampas_10000BP, up to the limits of our resolution for statistics unaffected by biases due to using different sequencing technologies (Figure 2a)"
This is the figure that does not include the Laguna de los Pampas specimen. And continue: "The most plausible explanation is that LagunadelosPampas_10000BP belonged to an ancestral Southern Cone population that split from Central East Brazil and Central Andes groups by 10000BP and was geographically in the CSC by that time before differentiating into distinct components."
This makes sense, it is the oldest sample and must have come, either from Brazil (Amazon or Atlatic Coast) or perhaps from the Central Andes (Peru or Bolivia).
They continue: "Neither PeñasdelasTrampas1.1_8800BP, from Southern Puna in Northwest Argentina, nor LosRieles_5100BP from Central Chile, showed affinity to LagunadelosPampas_10000BP, so we could not make a definitive statement about their relationship to this individual."
Therefore the Northern and Western samples (Chile, and the border area of Argentina with Bolivia) were not related to the Laguna de los Pampas sample. So, one would imagine it is associated to the Brazilian samples. But the paper ignores this issue. No further refrence is made to a possible Brazilian origin. The paper immediately jumps to the Anzic sample, 12,500 years old, from the Rocky Mountains in Montana, USA.
The paper says:
"We evaluated the affinities of LagunadelosPampas_10000BP to Anzick, a 12500BP individual from present-day Montana, USA, with distinctive genetic affinities to early South Americans relative to later ones. Chile_LosRieles_12000BP showed the strongest affinity (∣Z∣ < 4.1), followed by weaker affinity with LagunadelosPampas_10000BP (∣Z∣ < 2.6). However, since these three individuals were positioned together as a clade in an outgroup-f3 neighbor-joining tree (Supplementary Figure 1), both probably harbored a distinct Anzick-related genetic component. Affinity with Anzick in early South America, and absence thereof, has been associated with at least two independent migration waves and population replacement. However, the fact that LagunadelosPampas_10000BP also exhibits excess allele-sharing with later Southern Cone individuals without a significant genetic affinity towards Anzick, suggests that this individual may have been admixed between a basal Southern Cone lineage and a basal Anzick-associated lineage, and thus these Anzick-related lineages may not have been completely replaced."
What does this really mean? The Chilean sample from Los Rieles, 12 ky old is closer to the 12.5 ky Anzic sample. The ∣Z∣ formula, is simple, it is a measure in modulus or absolute value (the magnitude of a real number without regard to its sign, so -4 and +4 have the same modulus) of Z. Z, is the "Z score", a statistical tool used to validate admixture. If the value is less than 2, it means there is no evidence of admixture. if it is larger than 3, it may suggesting genetic shareing and admixture.
They say that it is known that ancient South American Natives had affinity with Anzic, while later ones did not. And that this suggests two waves of people entering South America. An older one with Anzic affinity and a more recent one, that had a different genetic makeup. But then they say that the 10,000 BP Laguna de los Pampas sample didn't have "significant genetic affinity towards Anzic" despite being ancient, and also "exhibits excess allele-sharing with later Southern Cone individuals." They conclude that he was a mixture of a both groups.
But, then they did another modelling and found a quirk! "The placement of LagunadelosPampas_10000BP was more ambiguous, appearing as an isolated lineage (3 models) or grouped with the Central Argentina JesusMaria_8500BP (5 models), or the Middle Holocene Argentinian Pampas (7700-6800BP) (1 model), consistent with its basal position in CSC diversity." So his placement was "ambiguous" and "isolated"
I believe that there aren't enough "ancient" genomes from South American to clearly understand the tree, the roots, the flow of people. Until more remains are discovered and sequenced we will find papers like this one, with a lot of amgiguity and conjectures.
Laguna de los Pampas. More information
A previous paper by Roca-Rada et al. (2021) reported that the Laguna de los Pampas person lived 10,223–9,764 Cal BP, and carried the mtDNA D1j haplogroup. The authors suggested that "D1j mitogenome in Laguna de los Pampas is basal in the D1j phylogeny and supports the hypothesis that D1j spread from the Pampas. Interestingly, a cranial morphometric study showed some affinities between the Early Holocene sites of Laguna de los Pampas and Lagoa Santa (Brazil) (Menéndez et al., 2015)." At last! a link between the Brazilian Lagoa Santa people and Laguna de los Pampas. The 2025 paper ignored this fact, it never explores the Brazilian option.
D1j mtDNA
The 2021 paper continues: "Furthermore, the D1j haplotype from Laguna de los Pampas lacks the T152C substitution but has the characteristic C16242T and T16311C substitutions. García et al. (2012) argue that the mutations at T16311C and T152C co-occur in both D1j and other D1 haplotypes found in central Argentina and propose that the substitution at T152C preceded the one at C16242T. Again, the ancient mitogenome from Laguna de los Pampas does not support this hypothesis as our observations indicate that the substitution C16242T preceded T152C. Nevertheless, it should be noted that 152 and 16,311 are mutational hotspots as described by Soares et al. (2009), increasing the odds of a recurrent mutation event." In other words, "hotspots" mean that a mutation can happen time and time again.
Comment: Doesn't this "hotspot" concept make the basics of genetic mutations a flimsy structure on which to build bold claims? Time and time again we are told that specific substitutions (mutations), such as one at position XXX that defines a haplogroup is then passed on to ALL future generations, and then, by chance, a later YYY mutation is added to the genome defining another haplogroup passed on to all those who come from that woman and her lineage. So looking at someone carrying both XXX and YYY we can identify them and place them in the branching tree, and the one with only XXX belongs to another branch. Now I learned a new concept, "mutational hotspots" that means that these mutations not as invariant as I had imagined. I will look into this in future posts.
So, the Laguna de los Pampas person had an ancient D1j mtDNA, distinct from the Anzic (D4h3a); the Los Rieles mtDNA has not yet been informed. D1 is one of the founding lineages of Amerindian mtDNA and the D1j derives from the slightly older D1g haplo.
The D1j mtDNA haplo is ancient, de Saint Pierre (2017) gave it a very old divergence date from D1g: 16.7 ± 9.4 kya. We have already mentioned the paper by Roca-Rada et al. (2021); in it the team "confirms that the D1j mitogenome from Laguna de los Pampas (LLP.S2.E1) is basal to the entire D1j clade." and finds the "TMRCA estimates for D1g (95% highest posterior density interval: 20.9–11.7 kya) and D1j (20.8–11.5 kya)."
Future research and more data should clarify the origins of these people.
Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall ©
No comments:
Post a Comment