David Reich

And as we did that, the enrichment for genetic mutations that affect traits got higher and higher.

So whereas it was only 15% when we didn't use our selection statistic, when we required the selection statistic to be above about five, there was about a five-fold enrichment for mutations that cause traits.

Sorry, what is the selection statistic?

This is the statistic we use to measure whether a mutation is changing over time significantly in a non-zero way.

So it can be approximately thought of as a normally distributed statistic, a Gaussian statistic, which is the number of standard deviations the statistical value is away from zero, where zero is no natural selection.

It's not exactly that, but it's close to that.

And so if this statistic is above five, we see about a five-fold enrichment in mutations that affect a trait.

And so instead of 15% of the mutations that are positive,

random affecting the trade, it's like 60 or 70 that are affecting the trade when we slide our statistic upward.

And this is providing completely independent evidence that these sites are real.

And as you slide above five, there's no more enrichment.

So our interpretation of these results and that we were able to

validate and show that these interpretations made sense using computer simulations of our process our interpretation of this result is that once you slide the statistic above five essentially all the signals of natural selection are real um okay and so just to make sure i understood you're saying look in order to figure out what alleles have been under selection your model uh

That's exactly right.

And this is like a brilliant idea that Ali had.

And it really abandons the traditional approach of assigning statistical significance to mutations that cause a trait, because we're just using an external piece of information, the

the correlation to traits measured in a completely different way to read off the probability mutations are real.

So we can ask how much enrichment for real signal is there given a particular selection statistic.

And if it's halfway enriched to the plateau, the correct interpretation of that we're able to show is that 50% of the mutations are really selected.

If it's three quarters of the way,