But that doesn't help us to know about ourselves unless we know in detail what the selective environment was, and what kinds of heritable variation was present in our gene pool. And we don't know those things. So why are we so seduced by invented stories about these things?"

Hang on: we can't understand adaptations - unless there are fossils?!?

What about molecular residues? What about current utility? What about current variation? There is a considerable quantity of evidence relating to these issues lying around - even without fossils.