Friedrich Nietzsche - Outside the Lecture hall lyrics

"In order to prove that man after all belongs to the good natured animals, I would remind you how credulous he has been for so long a time. It is now only, quite late, and after an immense self-conquest, that he has become a distrustful animal. Yes, man is now more wicked than ever." I do not understand this; why should man now be more distrustful and more wicked? "Because he now has - and needs - a science!