text: 50. Natural Selection and Altruism on The Tube – Part 1: Tube Utopia
  Here's a little story!
  It's completely imaginary.
  No names have been changed because it's all completely made up and in no way bears any relation to the real world.
  Let's suppose that you, the reader, are a lovely person and you make it a frequent habit to give up your seat on the tube whenever you see a person who needs it more… a pregnant lady perhaps, a young person on crutches, or just a mother overloaded with shopping.
  Why do you do this? Well, I guess we've already answered that question, it's because you're a lovely person!
  If only there were more of you in the world (or on the London Underground at least). In fact let's imagine that the entire London Underground is full of lovely people who always give up their seat whenever they see someone who needs it more.
  Let's call them Tube-Doves.
  Suddenly, the London Underground becomes a different world, people actually smile. The journey never gets too uncomfortable, life is good. Admittedly, it costs you, a Tube-Dove a little something to be so nice. Sometimes your legs may start to get tired from finding yourself without a seat on some tube journeys, but it's not so bad, because whenever things start getting too difficult, another lovely Tube-Dove voluntarily gives you their seat.
  Tube Utopia!
  But then one day it starts to go wrong....
  A newcomer to this beautiful imaginary world arrives on the scene, this newcomer looks a little tired, so a resident Tube-Dove duly gives him their seat. The newcomer enjoys a tube ride of comfort. Unfortunately he misses the overall point that he should, in turn give up his seat when someone needier appears. Either he doesn't realise, or he simply doesn't care. He completes his journey thinking "Wow this place is cool, I'm gonna ride the tube ALL the time and I'm gonna tell ALL my friends about this."
  He is a Tube-Hawk.
  So he tells all his friends. They all start to ride the tube. His friends are ALL Tube-Hawks. They NEVER give up their seat.
  Pretty soon, all of the Tube-Doves have gotten fed up and started walking, riding, or driving. Either that or they've adopted an 'if you can't beat them, join them' attitude, and become died-in-the-wool Tube-Hawks themselves.
  Now in our imaginary tube world, nobody EVER gives up their seat. Most definitely not Utopia!
  Seasons come, and seasons go. And then disaster strikes!
  It is now winter and a very particular strain of flu invades the population of tube travellers. When it strikes, the virus is particularly bad for people who have spent too much time on their feet. The best course of action is to sit down for a while, and get some rest.
  Unfortunately, in a population of Tube-Hawks this is impossible and soon people are fainting, and throwing up and being hospitalised left right and centre.
  The London Underground becomes a ghost town, a silent network of empty carriages shuttling pointlessly from stop to stop.
  Ironically, in a population of Tube-Doves, the effects of this virus would have been minimal because a traveller would have been able to get a seat if they really needed it. Not so, in a population of Tube-Hawk's.
  But of course, as we've seen, a population of Tube-Doves won't survive an invasion of Tube-Hawks, so that's too bad.
  At this point, you're probably thinking, "this is all very nice but is there a point here?"
  There is. But that's in Part 2.
  For now I'll use some impeccable logic to make a couple of observations...
  Since the London Underground that we know and love is not a spew spattered ghost town, this must mean that we (the population) are not a bunch of selfish Hawk so-and-so's.
  But neither is it a blissful Utopia. So we clearly aren't a population of lovely Doves.
  But I think we probably knew that already…
  Picture of a Tube-Dove (OK, so it was taken on the NYC subway, but hey) taken from Joe Shlabotnik's Flickr photostream under the Creative Commons Attribution 2.0 licence.