Originally Posted by
Gannicus
You have a bias as well. And it's against G25 which I cant really remember why. Except maybe your results on there don't fit your worldview on how people and places should be.
On your point with Satsurblia vs. Kotias. Kotias is closer in time to when CHG groups were interacting with EHGs in the steppe. And it makes more biological sense to use Kotias for European admixture modeling. Satsurblia is used for more deep time modeling. It's almost like using Dzudzuana in a neolithic/mesolithic model.
I essentially googled this because I think you are oversimplifying G25 and If I spend a whole hour or whatever writing my own defense of G25, it would be a waste of my time:
PCA basis isn’t inherently invalid – G25 coordinates are derived from a PCA built with ancient genomes, which is conceptually similar to the PCA space scientists use in publications. qpAdm, formal stats, and supervised modeling often rely on the same PCA framework for visualizing population structure.
Correlation with formal models While G25 is not a formal f-statistics tool, supervised models on G25 data can often produce admixture proportions that track closely with qpAdm, especially when the reference set is chosen well.
p-values aren’t the whole story Even in qpAdm, p-values in the 0.05–0.2 range can be considered reasonable, especially when reference populations aren’t perfect fits. Chasing a p=1.0 is unrealistic because even published academic models rarely achieve that without overfitting.
gy which
Scientists do use PCA-based coordinates – The difference is that in academic work they generate their own PCA from raw data, but the underlying principle is the same. The main limitation with G25 is that it’s a fixed PCA space and coordinates are produced by projection rather than recomputing the PCA, which can introduce some distortion—but it’s still valid for exploratory work.
I'd like to know what papers you are referring to. The ones I have seen when it relates to European genetics, it's Kotias. And Satsurblia is used for deeper time modeling of Kotias itself.