"Thus, the modern phenotype of fair-skinned, blue-eyed Northern Europeans is the result of multiple waves of ancestry and adaptation—not a direct inheritance from any single ancient population."
This is what Steve Sailer calls "Ockham's butter knife." We know that Europeans in Scandinavia and the Baltic region were already very light skinned long before the Yamnaya, at the very beginning of the Mesolithic (Gunter et al., 2018; Mittnik et al., 2018). Two research teams have likewise estimated that light skin evolved in Europeans some 10,000 to 20,000 years ago (Beleza et al., 2013; Canfield et al., 2014).
Instead of assuming that light skin evolved multiple times, it would be simpler to assume that it evolved once in the northeast of Europe and then diffused outward, either through the demographic expansion of those populations or simply through gene flow of one sort or another.
Also, eye color is weakly associated with skin color. A polygenic measure of skin color would tell us little about the evolution of eye color.
"Although DNA variants within the MC1R gene are strongly associated with light skin and red hair color, no detectable association with eye color was found in our large GWAS, in line with previous albeit smaller-sized GWASs of more limited statistical power. Similarly, other DNA variants strongly associated with skin and hair color within genes, such as SILV, ASIP, and POMC, showed no statistically significant effect on eye color in this study, nor in previous studies. Moreover, we also identified 34 genetic loci that were significantly associated with eye color, but for which there is no report of significant association with hair and/or skin color." (Simcoe et al., 2021)
References
Beleza, S., A.M. Santos, B. McEvoy, I. Alves, C. Martinho, E. Cameron, et al. (2013). The timing of pigmentation lightening in Europeans. Molecular Biology and Evolution 30(1): 24-35.
Canfield, V.A., A. Berg, S. Peckins, S.M. Wentzel, K.C. Ang, S. Oppenheimer, and K.C. Cheng. (2014). Molecular phylogeography of a human autosomal skin color locus under natural selection. G3, 3(11): 2059-2067. https://doi.org/10.1534/g3.113.007484
Günther, T., H. Malmström, E.M. Svensson, A. Omrak, F. Sánchez-Quinto, G.M. Kilinç, et al. (2018). Population genomics of Mesolithic Scandinavia: Investigating early postglacial migration routes and high-latitude adaptation. PLoS Biol 16(1): e2003703. https://doi.org/10.1371/journal.pbio.2003703
Mittnik, A., C-C. Wang, S. Pfrengle, M. Daubaras, G. Zarina, F. Hallgren, et al. (2018). The genetic prehistory of the Baltic Sea region. Nature Communications 9(442) https://doi.org/10.1038/s41467-018-02825-9
Simcoe, M., A. Valdes, F. Liu, N.A. Furlotte, D.M. Evans, G. Hemani, et al. (2021). Genome-wide association study in almost 195,000 individuals identifies 50 previously unidentified genetic loci for eye color. Science Advances 7(11): eabd1239
"Thus, the modern phenotype of fair-skinned, blue-eyed Northern Europeans is the result of multiple waves of ancestry and adaptation—not a direct inheritance from any single ancient population."
This is what Steve Sailer calls "Ockham's butter knife." We know that Europeans in Scandinavia and the Baltic region were already very light skinned long before the Yamnaya, at the very beginning of the Mesolithic (Gunter et al., 2018; Mittnik et al., 2018). Two research teams have likewise estimated that light skin evolved in Europeans some 10,000 to 20,000 years ago (Beleza et al., 2013; Canfield et al., 2014).
Instead of assuming that light skin evolved multiple times, it would be simpler to assume that it evolved once in the northeast of Europe and then diffused outward, either through the demographic expansion of those populations or simply through gene flow of one sort or another.
Also, eye color is weakly associated with skin color. A polygenic measure of skin color would tell us little about the evolution of eye color.
"Although DNA variants within the MC1R gene are strongly associated with light skin and red hair color, no detectable association with eye color was found in our large GWAS, in line with previous albeit smaller-sized GWASs of more limited statistical power. Similarly, other DNA variants strongly associated with skin and hair color within genes, such as SILV, ASIP, and POMC, showed no statistically significant effect on eye color in this study, nor in previous studies. Moreover, we also identified 34 genetic loci that were significantly associated with eye color, but for which there is no report of significant association with hair and/or skin color." (Simcoe et al., 2021)
References
Beleza, S., A.M. Santos, B. McEvoy, I. Alves, C. Martinho, E. Cameron, et al. (2013). The timing of pigmentation lightening in Europeans. Molecular Biology and Evolution 30(1): 24-35.
https://doi.org/10.1093/molbev/mss207
Canfield, V.A., A. Berg, S. Peckins, S.M. Wentzel, K.C. Ang, S. Oppenheimer, and K.C. Cheng. (2014). Molecular phylogeography of a human autosomal skin color locus under natural selection. G3, 3(11): 2059-2067. https://doi.org/10.1534/g3.113.007484
Günther, T., H. Malmström, E.M. Svensson, A. Omrak, F. Sánchez-Quinto, G.M. Kilinç, et al. (2018). Population genomics of Mesolithic Scandinavia: Investigating early postglacial migration routes and high-latitude adaptation. PLoS Biol 16(1): e2003703. https://doi.org/10.1371/journal.pbio.2003703
Mittnik, A., C-C. Wang, S. Pfrengle, M. Daubaras, G. Zarina, F. Hallgren, et al. (2018). The genetic prehistory of the Baltic Sea region. Nature Communications 9(442) https://doi.org/10.1038/s41467-018-02825-9
Simcoe, M., A. Valdes, F. Liu, N.A. Furlotte, D.M. Evans, G. Hemani, et al. (2021). Genome-wide association study in almost 195,000 individuals identifies 50 previously unidentified genetic loci for eye color. Science Advances 7(11): eabd1239
https://doi.org/10.1126/sciadv.abd1239