I can remember quite clearly the first time I saw someone fall off a bicycle.
I was walking down Bristol's main student thoroughfare, Woodland Road, and a guy did an accidentally emergency stop and went over his handlebars. What was remarkable about the incident was that the instant it happened, people started running towards him. As the unharmed cyclist sheepishly disentangled himself and got to his feet, he found himself surrounded by people asking if he was okay.
I've seen the same thing happen once or twice since and each time it's reaffirmed my belief that human kindness is instinctive. In fact it makes me feel so warm inside that I've begun wishing more cyclists would fall off their bikes.