[bhickey]

Under Hardy-Weinberg equilibrium we wouldn't expect a trait to go from 0.1 to 0.3 in a large population in four generations. This suggests that the trait is subject to selective pressure.

There are a lot of potential causes. In my estimation the two most likely causes—

First, hitchhiking. The mutation could be near some other beneficial mutation. The closer genes together on a chromosome the less frequently they'll be separated by crossing over events.

Second, it could have some other, presently unobserved cardiac effect that reduces infant or maternal mortality.

[FrustratedMonky]

My joke pet theory is that it helps with mouse control on PC's.

We are living our whole life at a desk, it is providing extra endurance for clicking.

[banish-m4]

We should just evolve ALPS key switches instead of fingertips already. Within a century, we'll look like the Prometheus engineer pilot.

[beacon294]

IIRC we would see any trait spread into its equilibrium point unless selective pressure leaned on the scale. So, it could go from 0.1 to 0.3 simply because it's population equilibrium is there.