What, if any, evolutionary advantage does intelligence give us?
Actually, less intelligent people are better at doing most things. In the ancestral environment general intelligence was helpful only for solving a handful of evolutionarily novel problems.
Suggested reading: “The Bell Curve: Intelligence and Class Structure in American Life” by Herrnstein, Richard J. and Charles Murray (1994)
You mean our ancestors did not really have to reason?
Evolution equipped humans with solutions for a whole range of problems of survival and reproduction. All they had to do was to behave in the ways in which evolution had designed them to behave—eat food that tastes good, have sex with the most attractive mates. However, for a few evolutionarily novel problems, evolution equipped us with general intelligence so that our ancestors could reason in order to solve them. These evolutionarily novel problems were few and far between. Basically, dealing with any type of major natural disaster that is very infrequent in occurrence would require general intelligence.
Suggested reading: “Evolutionary Psychology and Intelligence Research” by Satoshi Kanazawa, in American Psychologist; 65: 279-289 (2010)
Excerpt of an interview with Satoshi Kanazawa on intelligence. Continue HERE
SATOSHI KANAZAWA is Reader in Management at the London School of Economics and Political Science, and Honorary Research Fellow in the Department of Psychology at Birkbeck College, University of London. He has written over 80 articles across the fields of psychology, sociology, political science, economics, anthropology and biology. One such was his widely reported article “Why Liberals and Atheists Are More Intelligent” (2010). His latest book is called “The Intelligence Paradox: Why the Intelligent Choice Isn’t Always the Smart One” (2012).
WANDERLUST 
kanazawa is a moron
That is what we all should be…Morons!