We've all heard the [sayings][1] that we tend to prefer a half of a chocolate now over a whole chocolate in a month because we, as wild animals, are constantly seeking for sources. But what's really the evolutionary principle behind this? Isn't it just that we can better imagine a near pleasure? Btw I came across this when I realized that I actually even prefer less "sweets" in an hour before more in 2 hours. [1]: http://www.bbc.com/news/science-environment-26258662