Death by Design, a witty, fast-paced documentary by Peter Friedman (working with French researcher Jean-Francois Brunet), concerns an unlikely but fascinating subject: programmed cell death. Taking us deep into the mysteries of cellular biology, Friedman reveals the arcane reasons why some cells suddenly and automatically kill themselves, apparently triggered by signals from surrounding cells. Friedman employs some impressive, microscopic cinematography, but he knows most people are not inclined to look at the building blocks of life even for an hour. So he makes clever, allegorical use of other bits of film--clips of cars driving on the freeway, animation, Busby Berkley musical numbers, Harold Lloyd--to underscore the major points. Wonderfully entertaining and enlightening, Death by Design makes the invisible a thing of kinetic beauty.

The Life and Times of Life and Times is an edgy yet witty treatise on an enduring scientific and philosophical mystery: Why do we age? For that matter, why does anything in the material world change over time, and what does time mean in a biological sense? Several garrulous scientists seem happy to expound on one or another aspect of these questions in this stimulating documentary by Jean-François Brunet and Peter Friedman . Among other things, the film's talking heads remind us we know little about aging, and that evolution could have eradicated aging in human beings by now except for the fact that nature regards older, post-fertility people as, well, unworthy of preserving. But don't despair: Other species face the same dilemma, except scientists have learned to lengthen the life span of, say, fruit flies by delaying their reproductive period. If there is such a thing as a fountain of youth, it all comes down to genetics, The Life and Times tells us in its casually enigmatic way.