The essence of value

[Angrboda]

I think value is to biology what the arrow of time is to physics, it orients the difference between more successful adaptations and less successful ones such that the difference, in creatures that can abstract it, may be sought as a means of increasing one's reproductive fitness, the desirability of which drives our emotional appraisal of competing states (with more desirable ones appearing to yield more satisfactory emotional states).

In a sense, it's a feedback loop. Better adaptations yield cognitions that are more ardently sought, which drives the creation of more clones of the DNA that leads to organisms with more successful adaptations.