Hm...you might be right, although you can grow a phenomenal amount of food on two acres of land. If you have to throw in cattle, that would increase the amount of land needed for grazing, of course.
I did not intend to insinuate that 35 people per acres was sustainable - did not make that clear, though. Just making that point that the world is a very huge place, and the area that humans populate is practically miniscule.
With petroleum products you can
Not near as big as it seems though. Only about 13% of dry land is suitable for agriculture and intensive farming can go through fertile land in short order.
Regards,
GtG