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For the purposes of understanding human evolution the key is that we are now moving beyond looking for traits which emerged due to novel mutations (e.g., lactase persistence), and now trying to understand how selection and drift may work on standing variation.
For example, humans have become smaller in overall size, and also in cranial capacity, over the past 10,000 years.
But even though generating trees of mt DNA or Y markers is more tractable using a coalescent model, and it gives you a clean answer, it’s only a tiny slice of your ancestry. Perhaps better than nothing 10 years ago, but in the days of 450 K SNP chips probably outdated.
Luke Jostins reported this from a conference last year, so not too surprising.By aggregating evidence of directionally consistent intra-European frequency differences over many individual height-increasing alleles, none of which has a clear signal of selection on its own, we observed a combined signature of widespread weak selection.However, we were not able to determine whether this differential weak selection (either positive or negative) favored increased height in Northern Europe, decreased height in Southern Europe or both.One possibility is that sexual selection or assortative mating (sexual selection for partners in similar height percentiles) fueled the selective process.It is also possible that selection is not acting on height per se but on a phenotype closely correlated with height or a combination of phenotypes that includes height. First, simulations suggested that the genetic architecture is unlikely to be due to drift alone. Selection on quantitative traits isn’t magic, there’s a whole agricultural industry based around this phenomenon.