There may be some elements that are predictable. For example, from a demographic point of view, many people once they reach 50 will start to become more interested in health and fitness and typically, more young people are interested in extreme sports than are middle-aged or elderly people.
However, the actions of individual humans can be highly unpredictable – as can the response from others with whom they interact. Tiny stones throw in large ponds can occasionally have dramatic impacts which can only be understood through a complex adaptive system lens.
For example, when Martin Luther nailed his 95 Thesis to the door of All Saints' Church in Wittenberg in 1517 he wanted change. Others made the same requests for reform and were killed or ignored. Yet Luther’s words had an enormous impact on others and this unleashed a massive revolution and reformation beyond anything Luther could have imagined.
And, to use a more modern example, when Rosa Parks refused to give up her seat on a bus on December 1, 1955 in Montgomery, Alabama, she could not have predicted that her actions would greatly impact others and ignite the civil rights movement. http://www.youtube.com/watch?v=jJ1OO5iBWCQ
As I write this, the Kony 2012 movement going viral on the Internet. There have been 71 millions views (and counting) of this 30 minute video (http://www.youtube.com/watch?v=Y4MnpzG5Sqc&feature=share). I sit here wondering: Will a small group of people from Invisible Children impact enough other people in this complex adaptive system in which we live? Will a brutal killer be captured at last?