Neanderthals in America some genetic proof

 
I have already written about the possible entry of Homo erectus into America and its colonization of the New World until the arrival of Modern humans some (45? to 15? thousand years ago [kya] - the actual date is still uncertain).

Today I will look into the possibility that our distant "relative", Neanderthal (or Neanderthal) colonized America long before modern humans appeared on scene. And it will back up a previous post on Neanderthals in America.

Neanderthals some background

Actually little is known about their origin. In fact, the human family tree is still being drawn. Each expert has his or her own theory and read the facts differently. After reading different articles and papers, I believe that we can outline the following "sketchy" timeline:

1. Homo erectus left Africa and settled in Asia about 1.8 Million years ago. Most of their fossils (and, by the way, very old ones) have been found in the Far East (China, Indonesia), but more recent ones (800,000 years old) have been unearthed in the Caucasus.
2. Europe's oldest fossils were found by Bermúdez de Castro in 1997, at Atapuerca, Spain, the Homo antecessor it is an "archaic" hominin, and differs from the mor primitive H. erectus. They date from 780 kya ago.
3. Then there is the Homo heidelbergensis found in Europe, where it lived 600 to 400 thousand years ago. This leads to some questions:

• Did they originate in Europe from H. antecessor, and later moved back into Africa?
• Did they originate in Africa and migrate to Europe, replacing H. antecessor?

4.In either case, we, modern humans (Homo Sapiens) and Neanderthal evolved from H. heidelbergensis .
5. The Neanderthal split about 300,000 years ago We do not know where they split. Modern Humans did so in Africa about 200,000 years ago.
6. Scientists do not know where Neanderthals evolved; there are several possibilities:
Did some African H. heidelbergensis migrate from Africa into Eurasia and evolve there into Neanderthal? or did the European H. heidelbergensis evolve there into Neanderthals?
The outcome was the same, Neanderthals lived outside of Africa and occupied a range which covered most of Southern Europe, the Middle East, Caucasus and the Iran, Afghanistan area. See map below.

Neanderthal homeland.

None lived in Africa. They were encountered by modern humans when our ancestors moved out of Africa and took over the world, condemning Neanderthals to extinction.

Did we mix with them?

Research published in early 2011 by Yotova et al. [1] which focused on a very small part of a gene which is found on the X chromosome and known as B006 haplotype has come up with some interesting conclusions:

We share B006 with Neanderthals. And it is clear from the map below (taken from [1]) that it is very common outside of Africa and, non-existent in Sub-Saharan Africa, which suggests that it comes from a non human gene pool. That is, some hominin living outside of Africa and that later passed on this haplotype to modern humans: Neanderthal.

Worldwide distribution of B006 haplotype based on a worldwide sample of 6092 X chromosomes. From [1]

Notice that America has the highest prevalence of B006 in the whole world! (centered on Canada's west coast).

Let me qute Yotova:

" the evidence for Neandertal origin of B006 appears very strong. [...] Outside Africa, B006 is found in all habitable continents including Australia, as determined from a remote community of isolated indigenous Australians living in Central Australia [...] The ubiquity of B006 lineage reflects a worldwide contribution of Neandertal lineages to non-African genomes. It indicates very early Neandertal admixture prior to successful range expansion of the population ancestral to virtually all contemporary non-African populations" [1]

A previous paper (Zietkiewicz, Yotova - 2003) [2] on B006, stated that "this lineage could have left Africa before the expansion (as early as 160,000 years ago) and admixed, outside of Africa, with the expanding [human] lineage".
The map included in that paper is interesting, and I include it below, and as you can see it repeats the same pattern as the map above but, adds some interesting data:

B006 distribution map. From [2]

"Different colors, if present, indicate different Tn alleles shared by the same B haplotype."[2]

The map shows that America and Europe share the same Tn allele (in green in the map), which according to Table 1 in [2], is T16 (out of the 74 cases of this T16 allele, 47 appeared in America, 14 in Europe, 10 in Asia and 3 in Africa. It is predominantly American. On the other hand, the other allele (T15) did not appear in America at all.

Notice how the "green" T allele in the Old World is concentrated in the Neanderthal homeland!

But, believing in the "out of Africa" theory and the relatively recent population of America, the authors of paper [2] however disregarded American data in their analysis: "(disregarding the exceptionally low S2 value of 0.2 in the Americas)." The formula they use in their calculations was:

E(s²) = g_e x μ

Where g_e is the number of generations (at approx. 25 years per generation) since the population began to expand rapidly and, μ is the rate of mutation, and s² is the standard deviation.

They took the mutation rate μ=2.3×10^-5 and "estimated the time of the non-African lineage expansion (ge from eq. [5]) to be 4,040–4,260 generations, or 101–107 kya." [2] . That is, the time since humans emerged from Africa.

The same formula, applied to America gives: 188 kya!! Nearly 190,000 years. In other words, The lineage had all that time to evolve in America.

Discussion no the meaning of this. Lets highlight the main points:

• The highest frequency of B006 occurrence is not in Neanderthal's homeland (Map 1) but in America : 25% approx. prevalence in America vs. 10% approx in Europe.
• B006 has two Tn alleles. One of them, T16 is found in America: almost exclusively there, with 64% of the world's T16. That is followed by 19% in Europe, and the rest in Asia (14%) and Africa (of American Origin or Arabe Slave trade). T15, the other allele is not found in America, it is mostly (88%) Asian.
• So there is clearly a Europe-America link and, as T15 is not found in America and it is very common in the supposed homeland of Amerindians (Asia), there is a clear Asia - America "gap" or disconnection.

Devil advocate: Orthodox science explains the loss of the predominant B haplotypes found in Eurasia and the increase of B006 as follows:

"However, the loss of two haplotypes frequent in Eurasia (18.8 and 7%) and the rise in frequency of a third haplotype rare elsewhere, indicate a major population bottleneck in the peopling of the Americas. Although genetic drift appears to have played a greater role in the genetic differentiation of Native Americans than in the latitudinally distributed Eurasians" [3]

In other words the cause is either :

• A "founder effect" is the cause: a small group of Asians entered America and so they had a limited "gene pool" to begin with, all other Amerindians derive from this small group.
• or "population bottleneck" : a large diversified population is drasticall reduced (illness, famine, etc.) and the few that survive, and repeople the region, have a limited or restricted gene pool

We side with an opposite point of view which can be supported with the previous data:

Neanderthal had the B006 T16 lineage, and wandered into Asia, well beyond his European-Levantine homeland. There, he crossed into America, perhaps finding Eastern Asia unfriendly or already peopled with H. erectus.
America was empty, unpeopled so they expanded into a new continent free from competing hominids.

But we have evidence from another source, Blood, Amerindians and Neanderthals have a very high frequency of O blood group:

Neanderthal blood groups.

The blood of two Neanderthal individuals has been analyzed and found to belong to the O blood group. So it dates back at least to their days, and it may even be much older: "The results however suggest the presence of the human O01 allele already in the common ancestor of Neandertals and modern humans and thereby confirming an emergence of the O01 allele more than 1 Mya predating the divergence of the modern human and Neandertal populations".

Furthermore, they concluded that there was " a potential selective advantage of the O allele" [4] within the Neanderthals, meaning that it was a very common blood group in that population.

Unsurprisingly, Amerindians belong, almost exclusively to the O group (85.5% in North America and 90.9% in South America vs. a global average of 69.2% ). A group of Neanderthals migrating to America would have taken their O group with them.

"All major ABO blood alleles are found in most populations worldwide, whereas the majority of Native Americans are nearly exclusively in the O group [...] in all American populations, the same set of haplotypes O1, O1v, and O1v(G542A) was present" [5]

The authors believe that this is due to a founding population effect and suggest that the O1v(G542A) mutation found only in Amerindians, "could have emerged in Beringia, probably during the differentiation process of Asian lineages that gave rise to the founding population of the [American] continent"[5]

Ahh, the out of Asia and into Americas theory is so ingrained! please le me point out that: (O1v(G542A)), have not been found in Asians, suggesting an Ameri can origin of the allele or, perhaps a Neanderthal (pre-h. sapiens) origin.
It is interesting to point out that O blood allele appears in a large quantity of variations, this must clearly indicate that it evolved selectively and diversified, lets read about this diversity:

"Far from being monomorphic, at the sequence levels Native Americans present a variety of O haplotypes, some isolated geographically (such as O05 and Ov7 in the Cayapa, O32 and O33 in the Aymara), some shared with other human populations (O1 and O1v), and one haplotype called “O1v542” which has been found in all Native American populations screened at this level (Nahua, Mazahua, Maya, Mexican Mestizo, Cayapa, Aymara) and may very well be unique to the Americas (Estrada-Mena et al., 2009). [6]

The alleged "cradle" of Amerindians, Asia, is the highest in the world for type B blood allele (America is the lowest - and mainly in Western Alaska). Furthermore it is the rarest blood allele (only 16% of mankind has it).

Closing comments
Perhaps more research and field activities will unearth Neanderthal remains in America or, as genetic studies advance, they will provide more evidence and let us settle this issue.

Sources

[1] Yotova et al., (2011). An X-linked haplotype of Neandertal origin is present among all non-African populations 25.01.11. You can read it here:
http://operatorchan.org/z/src/molbev.msr024.full.pdf
[2] Ewa Zietkiewicz, Vania Yotova, Dominik Gehl, et al. (2003), Haplotypes in the Dystrophin DNA Segment Point to a Mosaic Origin of Modern Human Diversity Am J Hum Genet. 2003 November; 73(5): 994–1015. Published online 2003 September 25.
[3] Bourgeois, S., Yotova, V., Wang, S., Bourtoumieu, S., Moreau, C., Michalski, R., Moisan, J.-P., Hill, K., Hurtado, A. M., Ruiz-Linares, A. and Labuda, D. (2009), X-chromosome lineages and the settlement of the Americas. American Journal of Physical Anthropology, 140: 417–428. doi: 10.1002/ajpa.2108
[4] Carles Lalueza-Fox, Elena Gigli, Marco de la Rasilla, Javier Fortea, Antonio Rosas, Jaume Bertranpetit and Johannes Krause, (2008) Genetic characterization of the ABO blood group in Neandertals BMC Evolutionary Biology 2008, 8:342
[5] Benito Estrada-Mena, F. Javier Estrada, Raúl Ulloa-Arvizu, Miriam Guido, Rocío Méndez, Ramón Coral, Thelma Canto, Julio Granados, Rodrigo Rubí-Castellanos, Héctor Rangel-Villalobos, Alejandro García-Carrancá, (2009). Blood Group O Alleles In Native Americans: Implications In The Peopling Of The Americas. American Journal of Physical Anthropology; 142(1): 85 - 94
[6] Fernando Villasnea, (2010). Evolution of the ABO Blood group locus in Pre-Columbian Native Americans.

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