Actually an interesting take on this is in the book:

Who lives, who dies and why by Laurence Gonzales

http://www.amazon.com/s/ref=nb_sb_ss_i_1_10?url=search-alias%3Ddigital-text&field-keywords=who+lives+who+dies+and+why&sprefix=who+lives+%2Cdigital-text%2C288

The point of the book is that conditioning and knowledge is not the most important aspect. A will to live and being able to handle adverse conditions mentally is what keeps someone alive. Frequently the 125 pound geek will survive while the macho he man dies.