Here is an interesting column by Ben Stein (of "Win Ben Stein's money" and "Ferris Bueller's day off" fame...He is also an economist). He is discussing the problem of scarcity and how this concept can be taken to extreme--and tragic--consequences.
Class: Thomas Malthus was a noted economist in the 19th century. One of this main ideas was the idea of a Malthusian trap. That is, because food only grows at a linear rate but population grows at an exponential rate (you can only grow so much wheat before you run out of land but people keep..umm..reproducing) there will eventually be mass starvation among people. Let me state that this theory has NOT been born out by history. This is due in part because of technological advances in food production but also because the population stopped having less babies.