We have to do far more very-long-term planning than in the EEA

As societies, perhaps. As individuals, probably not. I find it a bit odd that you mention a decreased risk of starvation at the same time as this item; needing to look forward a year or preferably several to make sure you didn't run out of food during the winter (or the winter after that) has been a major factor in the past. Even if you lived in a warm country, it seems like there would have been more long-term dangers than there are now, when we have a variety of safety networks and a much safer society.

Most prominently, our explicit beliefs matter more for decision theory than for signalling, whereas in the EEA the opposite was true.

Existential risks excluded, I'm not sure if this is true.