From what I have read, the large numbers of PP's in the early days of NA settlement (by europeans of course) were a result of a LARGE population boom in response to the large population drop of Native Americans due to European diseases.
Basically, Native Americans preyed on PPs until disease wiped out 60-75-80% on the human population allowing PP pop to skyrocket, and leading to the assumption they were always that numerous.
From what I have read, the large numbers of PP's in the early days of NA settlement (by europeans of course) were a result of a LARGE population boom in response to the large population drop of Native Americans due to European diseases.
Basically, Native Americans preyed on PPs until disease wiped out 60-75-80% on the human population allowing PP pop to skyrocket, and leading to the assumption they were always that numerous.
Just my 2 pennies.