Tautalus
Regular Member
- Messages
- 545
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- 1,380
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- Ethnic group
- Portuguese
- Y-DNA haplogroup
- I2-M223 / I-FTB15368
- mtDNA haplogroup
- H6a1b2y
Adaptive admixture—selection favoring individuals who inherited both a WHG derived RHD deletion and farmer derived beneficial alleles, amplified by a Basque eco evolutionary niche that reduced the cost of hemolytic disease—can explain the unusually high RhD negative frequencies in Basque and, through later Neolithic migrations from Iberia into Northwest Africa, in some Berber populations.
Abstract
The RhD-negative blood type exhibits statistically anomalous frequency peaks in geographically linked populations. The Basque population shows the world's highest frequency (~30-35%), while specific Berber populations in North Africa also display elevated frequencies (~15-20%). This paper presents a quantitative population genetics model synthesizing recent archaeogenetic data to explain this distribution. We developed a synergistic selection framework where the net selective advantage of the costly RHD deletion becomes positive when statistically associated with other beneficial traits. Our modeling indicates that admixture between indigenous European hunter-gatherers (carrying a high frequency of the classic RHD deletion) and migrating Neolithic farmers from the Near East (carrying the SLC24A5 allele for lighter skin) within the Iberian Peninsula created conditions where synergistic survival advantages drove rapid co-amplification of these traits. This process was uniquely amplified in the Basque region within a stable "Eco-Evolutionary Niche" characterized by geographic isolation, resource abundance, and a demanding physical lifestyle, which together buffered the mortality cost of Hemolytic Disease of the Newborn (HDN) and enhanced the fitness variance upon which synergistic selection could act. This pre-adapted lineage was then distributed via documented Neolithic gene flow to Northwest Africa, with molecular evidence confirming the European RHD deletion haplotype in Berber populations. Our quantitative framework explains the trans-Mediterranean allele distribution and provides testable predictions for future validation through ancient DNA analysis and population genetic simulations.
