I came across a paper (Fagundes NJR, Tagliani-Ribeiro A, Rubicz R, Tarskaia L, Crawford MH, Salzano FM, Bonatto SL. How strong was the bottleneck associated to the peopling of the Americas? New insights from multilocus sequence data. Genet Mol Biol. 2018;41(1 suppl 1):206-214. doi: 10.1590/1678-4685-GMB-2017-0087. PMID: 29668018; PMCID: PMC5913727.) that after statistic analysis concluded that the group that peopled America contained 250 individuals.
The number surprised me, seems to small! But the paper is conclusive "Our results suggest that, in agreement with previous studies, the effective size of the Native American population was small, most likely in the order of a few hundred individuals, with point estimates close to 250 individuals, even though credible intervals include a number as large as ~4,000 individuals."
Notice that the paper mentions "effective" population. This is a geneticist term that is defined as follows (Source): "Effective population size (Ne) is the size of a hypothetical ideal population with the same level of inbreeding or gene frequency divergence under random genetic drift as the actual population under consideration"
Ne is smaller than the census population (Nc) or actual number of individuals in a population because many individuals in a population may not reproduce and pass on their genes to the next generation. Factors like sex ratio, family sizes, survival of offspring, etc. influence the relationship between Nc and Ne.
As usual the methods lists that the authors took a relatively recent date for the peopling of America: "The lower limit for population split was set at 15 thousand years ago (kya)".
I am glad that the paper used samples taken from real Native Americans and not admixed "Latino" (European and Amerindian) people. However, the "Great Dying" altered the diversity and genetics of America. No pre-Hispanic samples were included in this paper. There was a greater diversity in the Americas before 1492. Those that survived, were those who adapted to the stress introduced by Old World diseases, famine, forced labor, war, displacement, etc. caused by the European conquest. Many lineages vanished as they couldn't adapt to the changing scenario (Natural Selection in action. Well done Darwin!).
Anyway, it is an interesting paper that does not go into too many details. The supplementary materials don't clarify much. I am an engineer, and know how to make sense of data, and graphic charts. But it seems that most genetic studies rely on "black boxes". They input some parameters, feed data, and the program they use provides an output. Who validates it is correct? Then we have vacuous comments with phrases and jargon like Tajima, Fu, π, etc. that put off a layman and sound scientific. Yet, they make me wonder. The output depends on the quality of the data that is input.
The point is, did a group of 250 effective population (maybe 1,000 census population) people America? I'd say NO.
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