In 2001 I worked on shots for a PBS special. The series animated different evidence of evolution and the changes and factors that go along with it. Evidentially, our eyes have evolved, and I spent some time learning about that, and them creating two animations of the human eye, and its evolution related features.
Most of the work for this Series was done on SGI's. The models for these shots was done on SGI, and the textures helped along in IRIX based Alias Studio Paint, but NT computers had just made their great dawn, and the compositing for these shots was done in Premiere and After Effects. All animation for the series was rendered in HD.
Other shots were less medical and more technical, like this shot below, explaining feeding ratios for animals in the wild at some point. This shot uses atmosphere, fog casting lights, glows, trick compositing, and animated Maya Paint Effects. Produced in Maya on an SGI, and composited using Alias Composer (similar to using Fusion).