[iguy]

In my limited understanding, the credible version of this story involves the transmission of quite crude information, like a response to famine.

Lots of animals starved, since there were animals, and the ability to tune the behavior on a time-scale of a few generations might have been valuable, so it might have evolved. The basics of our hormonal system have not changed much since very simple animals, I think.

[asianthrowaway]

Yes this is how I understood it too. Makes sense that such a feature would evolve when you think about it.