Sounds like the models are conflicted.

When my models get conflicted, I send them to therapy... ;-)

What was the sexual selection structure like in Tasmania? If women chose, they should be darker than UV should suggest, if men chose, they should be lighter

If women chose, they should be darker than UV should suggest, if men chose, they should be lighter

i don't think you can rest your laurels on one component in one case.* shit like this isn't deterministic. in many australian aboriginal cultures there was a tradition of geriatric polygyny, and they aren't particular pale for their latitude.

* this is a problem with many readers, they assume all (most) the variance on any given issue can to be reduced down to one component. if that was so, this sort of stuff wouldn't be mooted on weblogs.

Although personally I find the 2s theory extremely plausible, I think that in the particular case of skin color, the simplest answer is that there's not much land down there.

Look where the equator cuts on your map, then ask yourself where a random walk with such geographic constraints will take you? (If you know some history, you can explain more, for example the Bantu push down the eastern side of southern African, into Khoisan territory.)

Put another way: The more land there is to the north of where you stand, the lighter you are. The more land to the south, the darker. That's for the Northern Hemisphere, of course, in the Southern Hemisphere, there simply aren't very high latitudes - no northward counterpush to the southward push of populations to the north.