while you only just noted it at the end, sexual selection is also another factor. that is, the bird of paradise's tail is huge in the most successful males. it's also a hindrance to them. why would something that's actually not good for their survival be passed on? well, it's sexually selected in that it's a tell-tale (puns are terrible...) sign of other genes. that the bird had survived even with this hindrance means that it has other genes that the female wants in her young.
also you mentioned gould, and of course he advocated the theory of punctuated equilibrium, where evolution is very little except for in spurts when two species emerge. while i do think there are spurts often, i think he is wrong that it's so little in between its non-existent. he also claims humans haven't been evolving for 50,000 years and i think that's wrong. if you take another theory, that of group selection, you'll see undoubtedly that humans have been evolving and more rapidly than before, and that it is group selection that really messes with the punctuated equilibrium model. for non-humans, group selection is not happening (lack of communication skills), but for humans, i think a strong argument can be made. a recent book, The Righteous Mind, speaks about group selection and how it has laid the evolutionary framework for our moral foundation. the author makes a compelling argument about it and i cannot recommend this book enough. because of the development of language, we could share intentions (or not) truthfully (or not) with other humans. this has had profound impact on our genetics in reality.
the author talks about how babies will stare at things that don't make sense. that is, you can trick them to thinking a toy is moving through a block. they will stare at that longer than looking at a car moving behind a block. this shows some innate understanding of physics. similarly, babies can be shown puppet shows where a puppet is trying to make his way up a hill and another puppet helps him. when shown another puppet pushing him down, they stare longer. after, when given the choice of all the dolls, they most likely chose the one that helps other people. that is to say, we have an innate understanding of not being selfish. this is different than if it was helping them; puppies know who gives them food. but puppies don't care who gives other puppies food. we're mostly selfish, but not always. we're pretty unique among animals. he quotes one biologist as saying, "you will never see two chimps carrying a log". this shows the profound gulf that is there between ourselves and the most cladistically similar animals there are. somewhere in the evolution of humans, we changed from just being selfish to having a groupish overlay (the author speaks in metaphors a lot, and he says we're "90% chimp and 10% bee"). human evolution has been rapid in the past 50,000 years and it's why we are the way we are, and it's because of our ability to work in groups.