The butterfly effect is a theoretical phenomenon stating that a butterfly flapping its wings in one place can cause catastrophic cyclones in other parts of the world. This theory is impossible to corroborate, of course, but it introduces an interesting question of what seemingly insignificant daily choices can have on the world; had John F. Kennedy's brother not volunteered for Operation Aphrodite, it is likely that JFK would not have ran for president. Imagine the impact this would have had on the world as we know it. Likewise, the decision of an Indian man to journey to South Africa caused immense world change; while moving country is an enormous decision, its worldwide ramifications are so pervasive that it is hard to find someone who has not heard of that Indian man: Mahatma Gandhi. The smallest decision can be the difference between any number of situations unfolding; to put the world, and your own existence, into perspective, it is worthwhile realising that - had just one of your ancestors been in the wrong place at the wrong time - you would not exist. Humanity is itself the product of an almost infinitely unfolding number of decisions, and there is an ample array of historical evidence to support this. Here we'll explore 10 of them.
Honourable Mention: James Blunt Stops World War III
In June 1999, James Blunt, then a Captain in the military, received orders to attack the Russian army defending Serbian forces. Rather than risk causing World War III he laudably refused the order, knowing he could face a court martial for such an offence. This action wasn't exactly an insignificant choice - in fact it was more like the opposite - but some might say it came from a fairly insignificant source, and it is worth noting as it averted a potentially catastrophic war with the capacity to wipe humanity from the face of the earth.