To the question, what is life?, world renowned biologist Margulis and science writer Sagan (her coauthor on Mystery Dance, LJ 7/91, and her son) respond: Life is matter that chooses. Mammalian cells are descended from the amalgamation of different strains of ancient bacteria. All life is connected to us through time and space. Species of organisms diverge into new kinds, yet earlier patterns never entirely disappear. Every species of plant, animal, and fungus perishes, and similar new taxa evolve from them or their kind. The human species may eventually disappear, but something else will evolve from our kind. We learn that we are not the only creative and original creatures but part of a global aggregation. Yet while we are not the only species to make evolutionary choices, we are the ones whose choices will make a difference as to what type of planetary ecosystem we leave for those species that follow. Beautifully executed with numerous photos and illustrations, this thought-provoking work is recommended for general readers and informed lay readers.-Gloria Maxwell, Kansas City P.L., Kan.