John Napier is a world expert on the evolution of the human hand and foot. Not surprising, then, that in these Christmas lectures for young people given at the British Museum he is most eloquent in discussing these hallmarks of humanness. Napier coined the terms ""power grip"" and ""precision grip"" to describe the two essential hand functions. Napier, too, has emphasized that while other primates occasionally walk upright, only Homo sapiens strides in an intricate heel-first, big toe-last motion that is a marvel of efficiency and economy. For the rest, the book covers familiar ground: discussions of living primates; mammalian, primate, and human evolution; controversies about human antecedents; the significance of continental drift; and finally, the anatomical features that distinguish humans. He makes some admiring references to Lionel Tiger and Desmond Morris, but since he generally confines himself to physical char. acteristics, their controversial ideas are not dwelt upon. Napier's title derives from a hypothetical ""giraffid"" point of view. To the 18-foot-tall grazing animal the only difference between us and similar creatures is that we lack tails. Aside from this and a few other whimsical metaphors which might amuse young people, the book is a fine and handsomely illustrated adult summary of human evolution.