The global population is now more than 7 billion. Male, female, black, white, rich, poor, English, Bangladeshi. The possible combinations feel almost endless.
Of course they're not, but it would probably feel that way if you tried to list them all. 7 billion people and all of them different. If they walked past you at the rate of 2 every second it would take 111 years, without any breaks, for them to go past. Given 8 hour days, a 5 day week, a working lifetime of 45 years and no holidays you might manage to see just under 674 million go past; that's less than 10% of the total.
All these people, all of them special to themselves and all of them wondering from time to time what life would have been like if they'd been born as someone else.
But the idea that you might have been born as someone else presupposes the idea that there's a you that is separate from the body you inhabit.
Whilst some might see this as the start of an argument for the existence of God, who supplies the souls that can then inhabit the bodies, I'm much more inclined to see it as an example of how complexity, in this case our sense of self, can emerge from simpler components whose behaviour is governed by a much simpler set of rules.
For example, given a suitable supply of heat on a rotating planet and you can get a hurricane. All of the individual molecules simply obey the basic laws of physics but what emerges has a life of its own. So much so that some hurricanes even get given a name.
