Talk:Mexicans

Misinterpretation of sources

There are a couple of misinterpretations of two sources in this article here:

In studies made on the general Mexican population (this is, studies where there is no other kind of self-identification than that of being "Mexican") the European ancestral genetic component tends to overtake the indigenous composite. Said increase is the most pronounced on research done on chromosomal maternal ancestry, as while in studies made on self identified Mestizos the European maternal ancestry is as low as only 5%,[154] on studies done on the general Mexican population the European maternal ancestry increases more than 40 points, with it being 46%,[155] suggesting that nowadays a considerable segment of Mexico's population is left out when a study uses as samples only people who think of themselves as being Mestizos

Citation [154]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3217880 (Kumar, et al)

Citation [155]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1867092/ (Alkes et al)

Neither of these two sources are consistent with the Wikipedia statement. Kumar does not state anywhere that their sample identified as "Mestizo". The word Mestizo isn't anywhere in the article. The participants in that study are simply Mexican.

Furthermore, Alkes does not state anywhere that their Mexican sample is "46%" maternally European. Alkes compares the X-chromosomal Native American ancestry in their sample to the autosomal ancestry, to broadly infer the uniparental asymmetry of this Mexican sample. That's not the same thing as maternal ancestry. Kumar and Alkes both support a uniparental asymmetry for Mexicans, and nowhere in this resesrch is it implied that a Mexican's identification as "Mestizo" is related to their uniparental (haplogroup) ancestry.

From Alkes, et al (emphasis mine):

We used the mixture-of-binomials model to infer Latino ancestry proportions from European, Native North American, Native South American, and African ancestral populations; this computation approximates each Latino population as entirely descended from the ancestral populations we sampled. Results are reported in table 2 and indicate higher total Native American ancestry for LA Latinos and Mexicans (45% and 44%, respectively) than for Brazilians and Colombians (18% and 19%, respectively), which is in line with previous studies.21,22 We also observed uniformly higher Native American ancestry on the X chromosome (57% for LA Latinos, 54% for Mexicans, 33% for Brazilians, and 27% for Colombians), which is consistent with evidence of predominantly European patrilineal and Native American matrilineal ancestry in Latino populations.22

From Kumar, et al (emphasis mine):

Mexicans are, by and large, descendants of Native American and European (Spanish) ancestors [40]. Historical accounts also document African slavery in Mexico during the 16th-18th centuries [41-43], another source of admixture in the Mexican population. The admixture estimates compiled by Lisker et al. [44] using data derived from classical genetic systems reported in previous studies in Mexico [45-52] identified African and/or European genetic variation in all Mexican regions and groups analyzed. For mtDNA variation, some studies have measured Native American, European and African contributions to Mexican and Mexican American populations, revealing 85 to 90% of mtDNA lineages are of Native American origin [53,54], with the remainder having European (5-7%) or African ancestry (3-5%) [54]. Thus the observed frequency of Native American mtDNA in Mexican/Mexican Americans is higher than was expected on the basis of autosomal estimates of Native American admixture for these populations i.e. ~ 30-46% [53,55]. The difference is indicative of directional mating involving preferentially immigrant men and Native American women. This type of genetic asymmetry has been observed in other populations, including Brazilian individuals of African ancestry, as the analysis of sex specific and autosomal markers has revealed evidence for substantial European admixture that was mediated mostly through men [56]. In our 384 completely sequenced Mexican American mitochondrial genomes, 12 (3.1%) are of African ancestry belonging to haplogroups L0a1a'3', L2a1, L3b, L3d and U6a7; 52 (13.6%) belong to European haplogroups HV, JT, U1, U4, U5; and K and the majority (320, 83.3%) are of Native American ancestry, which is very similar to previous reports [53,54]. After removing the related individuals from our maternal lines and those of European or African descent, 215 newly sequenced unrelated mtDNA genomes of Native American ancestry were identified for founder haplogroups A2, B2, C1, D1 and D4e1c (new sister lineage of D2 found in Mexican Americans). These complete mtDNA sequences were analyzed together with 353 previously published sequences belonging to the four primary Native American founder haplogroups A2, B2, C1 and D1 and their Asian sister clades (A4, C4 and D4e; see additional file 1 for details).

There is nothing in any of these studies saying that any Mexican sample has a substantial European maternal ancestry. - Hunan201p (talk) 23:53, 12 June 2022 (UTC)

Consider that the X chromosome is matrilineal aswell. Pob3qu3 (talk) 19:38, 13 June 2022 (UTC)

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South China

The following is just a copypaste from a recent discussion at another talk page that relates to the same content:

There is nothing in Zhang, et al. (2022) that substantiates this claim: 'Ancestral Native Americans' formed from an 'Ancestral Native American' lineage which diverged from East Asian people around 36,000 years ago somewhere in Southern China.

What they do say is that the Red Deer Cave people form one part of the amalgamation of Native American ancestry. The IP editor on the other hand speaks as if "Ancestral Native Americans" began with that one population. That is original research, and wrong. Even if Native Americans were direct descendants of Red Deer Cave, which they are not, the actual "Ancestral Native Americans" originate from the mixing of multiple populations, not from Red Deer Cave or ancient East Asians alone. And this mixing happened north of China. As Austronesier pointed out, it involved Ancient East Asians in Northeast Asia rather than southern China.

The "northward migration and mixing with ANE" scenario is original research; these papers don't tell this tale.

Further, regarding [1], their source cites Raghavan 2014 for the percentage of ANE-related ancestry in Paleo-Americans:

Extended content

Our tree model grouped ANEs MA-1 and AG-2 with Western Siberians (Mansi and Nenets), suggesting a genetic link between ANEs and modern Western Siberians (Fig. 7). Furthermore, TreeMix estimated that 41% (95% CI: 36%–45%) of the ancestry of Andean Highlanders, the Native Americans, is attributable to the ANE lineage (Fig. 7; Supplemental Fig. S16). This is consistent with previous reports that Paleo-Americans trace ∼42% of their autosomal genome to an ancient Eurasian lineage related to MA-1 (Raghavan et al. 2014).

...so this is actually a secondary source for this figure. My main problem is that the IP has listed the ancestral components as "sister lineages" of East Asians and Europeans, when it is more accurate to describe them as ancient East Asians and ancient West Eurasians, or just ancient Eurasians. Hunan201p (talk) 15:37, 4 April 2023 (UTC)

Hello, as I said at the talk page there, I have no problems with the part about Southern China to be removed. The other part is sourced by this 2022 book by Jennifer Raff:

AROUND 36,000 years ago, a small group of people living in East Asia began to break off from the larger ancestral populations in the region. By about 25,000 years ago, the smaller group in East Asia itself split into two. One gave rise to a group referred to by geneticists as the ancient Paleo-Siberians, who stayed in Northeast Asia. The other became ancestral to Indigenous peoples in the Americas.

I cited the summary article in Sapiens ([2]).

Another problem with the Wong paper may be that it is about Indigenous Andean Americans, rather than Indigenous Mexican groups. Other papers estimated different amounts of ANE ancestry for Native Americans. This (Moreno-Mayar et al. 2018) for example estimate between 14% and 38% of Native American ancestry may originate from gene flow from the Mal'ta–Buret' (ANE) population, and say:

Using demographic modelling, we infer that the Ancient Beringian population and ancestors of other Native Americans descended from a single founding population that initially split from East Asians around 36 ± 1.5 ka, with gene flow persisting until around 25 ± 1.1 ka. Gene flow from ancient north Eurasians into all Native Americans took place 25–20 ka, with Ancient Beringians branching off around 22–18.1 ka.

The book I cited, probably cites Moreno-Mayar et al. on that. Hope that helps.94.131.108.230 (talk) 17:43, 4 April 2023 (UTC)

Sapiens.org is a 7 year old web magazine. Their faulty summary of Raff's book isn't Raff's book. If you actually read Raff's book and want to give a direct quote and page number where she says anything like that, I would be interested to hear it. Meanwhile Meltzer cites Moreno-Mayar and says on page 170:

The ancestors of Native Americans derive from descendants of Ancient North Siberians and Ancient North Eurasians on the one hand, (exemplified by the genomes of the Yana and Mal'ta individuals, respectively), and a population of Ancient East Asians (signified by the Tianyuan individual). From those groups emerged the deepest ancestors of Native Americans, who became separated far in far northeastern Asia from their Siberian and Asian ancestors around the time of the LGM. Part of the population stayed in Siberia (the Ancient Paleo-Siberians, seen in the Kolyma genome), while others moved east across Beringia.

- Hunan201p (talk) 23:41, 4 April 2023 (UTC)

The Sapiens org report on her book gave excerpts out of the book, the quote I used is such an excerpt. (Excerpted from Origin: A Genetic History of the Americas. © 2022 by Jennifer Raff. Published by Twelve Books. All rights reserved). Furthermore, the article on Sapiens org seems to have been written by the author of the book, Jennifer Raff. There are also two graphics made by Jennifer Raff showing the same as in my used quote (the description of graphic 1: "Roughly 36,000 years ago, a group living in East Asia began journeying east, eventually crossing Beringia into present-day Alaska, where some populations expanded south as the ice sheets melted around 17,000 years ago. - Jennifer Raff")

The quote of Meltzer 2021 is basically saying the same. Except that he seems to make a mistake by calling the East Asian like ancestry among Native Americans as "signified by the Tianyuan individual". That's probably a mistake. Tianyuan probably did not directly contribute to Native Americans. But anyways, thank you for your points and the Meltzer paper link.94.131.108.230 (talk) 05:31, 5 April 2023 (UTC)

I read Jennifer Raff's book day and night. The Sapiens.org webpage is not an excerpt, but a teaser. It stitches together various quotes from different parts of the book that will easily mislead any unassuming person who reads it.

From the Sapiens.org link, Raff refers to the Beringian standstill hypothesis where the mixing takes place in Beringia rather than Siberia or further south in East Asia, as a result of northward migration. What the Sapiens.org link fails to show is that this is only one hypothesis that she summarizes. Most of what she talks about involves migrations to the south where the mixing between them and the ancient East Asians took place in East Asia or Siberia.

This is the actual content from pages 188-189 of Raff's book:

We know from later comparisons that the Mal'ta boys' people were direct descendants of the Ancient North Siberians from Yana (7). They were broadly ancestral to present day Eurasians. But in comparing his genome to present day populations from across the world, they found that he was also closely related to present day Native Americans; his population was directly ancestral to them. Mal'ta's population -- the ancient Northern Siberians, seems to have encountered the daughter East Asian population described at the beginning of this chapter around 25,000 years ago and interbred with them. Current estimates suggest that approximately 63% of the First Peoples' ancestry comes from the East Asian group and the rest from the Ancient North Siberians. We're not sure where this interaction took place. Some archaeologists believe that it occured in East Asia, suggesting that this is where the Siberians moved during the LGM.

There's also a case to be made for this interaction having taken place bear the Lake Baikal region in Siberia from genetic evidence, too. The ancient Paleo-Siberians, as mentioned earlier in this chapter, split from the East Asian ancestors of Native Americans by about 25,000 years ago. They are known to us from the genomes of an Upper Paleolithic person from the Lake Baikal region known to us from the genomes of an Upper Paleolithic from the Lake Baikal region known as UKY and a person from Northeastern Siberia dating to about 9,800 years ago known as Kolyma1. Closely related to Native Americans, these "cousin" genomes also show a mixture of ancestry from Ancient North Siberian and East Asian populations, although the proportion of East Asian ancestry is a bit higher than in Native Americans -- about 75%. The Ancient North Siberian gene flow into the East Asian ancestors of the Ancient Paleo-Siberians probably occured at the same time as into the ancestors of Native Americans -- between about 25,000 and 20,000 years ago. Because UKY lived in the Lake Baikal region some 14,000 years ago, some researchers argue, it seems likely that the meeting between East Asians and Ancient North Siberians occured in the Trans-Baikal region (8).

But other archaeologists and geneticists argue that the meeting of the two grandparent populations of Native Americans occured because people moved north, not south, in response to the LGM. In this scenario, Paleo-Siberian descendants, like UKY, could have been the result of a southward repopulation of Siberia out of Beringia. The reason for this is because both mitochondrial and nuclear genomes of Native Americans show that they had been isolated from all other populations for a prolonged period of time, during which they developed the genetic traits found only in Native American populations. This finding, initially based on classical genetic markers and mitochondrial evidence, came to be known as the Beringian Incubation, the Beringian Pause or the Beringian Standstill hypothesis. (9)

So the Sapiens.org link is not at all an excerpt. - Hunan201p (talk) 11:50, 5 April 2023 (UTC)

References