This is typical of the hand-wavy peak oil arguments.
An increased richness of culture or an increased scientific knowledge clearly don't require ever-increasing energy consumption.
Oppositely, the reason previous evolutionary jumps involved more energy per capita has been that ... cheaper energy has always previously available (ie, this a correlation, not a causation).
Edit: A modern laptop uses less energy than a desktop machine of twenty years ago, yet the laptop's user certainly experiences a somewhat higher level of "civilization" or whatever one would call it. Just a simple counter-example to "evolution always requires more energy per capita" claim.
http://gailtheactuary.files.wordpress.com/2012/03/world-ener...
It rather looks quite the opposite...
a) Humanity has plateaued in its energy usage; or
b) Some other energy source is increasing.
Any of these means oil has hit a peak (there'll be no cliff, though, as you explained). The alternatives are not acceptable (evolution stopped or, for the first time in five thousand years, stopped requiring more energy use).