" what passes for good science is little more than unfounded speculation."
Every writer has their own bias. Most research done, or paper written, are done so with a outcome in mind before they start. Sometimes they massage the data or facts to support their outcomes and sometime they ignore inconvenient data or even never publish at all if the outcome is not what message they want to project. Before you read any paper try to find out who paid for the paper or research. follow the money. If any "expert" cites other research or other papers see if they are in fact just citing their previous works to make their current work seem valid. If a writer only can find himself as an expert then the paper is worthless. Everyone sees the same sunrise, so if only he can see the sunrise, the light he is shining up your butt is not true sunlight.
All history is an interpretation of what happened, base on scant facts and a lot of conjecture. Not that they all get it wrong but facts can be viewed differently by different people or by the change of time. So any attempt to figure out what cause the PP to die off is just so much speculation.
Gives credence to "the medium is the massage".
JR