1. I mean for example why can't a kakapo fly? You could say flying is a waste of energy, but there's nothing wrong with a kakapo wasting his energy, flying is not a disadvantage, since he lives on an island with an abundance of food. So much food that to stop them eating it all they have somehow managed to evolve a system which stops them reproducing too often. Is there a Darwinian explanation for this? If not does it suggest epigenetics? I know quite often useless traits do not disappear. And I know sometimes you can evolve something that isn't necessarily helpful but that it keeps going anyway because it's not harmful. Then if you have a small population that turns into a large one (like with humans) you end up with lots of people having this useless trait because everyone is related to everyone else. 2. That's another question. How on earth do you manage to evolve not to have too many offspringwhen you would think that if one parrot came along and had lots of chicks and the other came along and only had 4 in his whole lifetime that the one with lots would be the one that ended up taking over.. even though that's a really bad idea. Edit: I was just thinking maybe sometime in the past there wasn't enough food and flying therefore because a big disadvantage. That's probably it. Thoughts?