Evolutionary Progressivism

wut is evolutionary progressivism as portrayed by Darwin in "The Origin of Species" and "The Descent of Man" and why is it right wrong?
I get the impression that the concept does not really work in the real world, because species don't increase in complexity / "perfection", but I dunno the specifics of how Darwin would have portrayed or explained it and if his views are now largely considered defunct.

>>6
it's a european history class :P
we got the option of choosing what to research and write about, one of them being evaluating the concept of progressive evolutionism, as detailed by Darwain. Seemed by far the most interesting topic to me (other than that, something about Marx's theory of history, the "freedom hypothesis" according to Dostoevskys, and Ivan Ilych's life, and I'd honestly prefer watching paint dry over writing about any of those, perhaps with the exception of the Marx piece.
It really doesn't matter whether or not you know anything about the pieces I am talking about, I may include any good ideas about evolutionary progressivism and why it does / does not work (currently of the mind it does not work). So if anyone has any ideas, really, I'd appreciate any and all help.
I assure you all I am not planning to relay on a bunch of posts in /sci/ to \write my paper for me :\