The basic idea behind evolution is rather simple: in times of difficulty not everyone survives, or at least not everyone reproduces. Those who are faster, bigger, taller, stronger, smarter, or whatever it is that makes for successful reproduction, will do just that. And those who lack the requisite capabilities will not reproduce, or not reproduce as prolifically. One way or another, the result is that, in those difficult times, future generations are more representative of the winners. The traits of the successful reproducers are passed on more often. This means the population undergoes a change—it evolves. Read more