A PICTURE IS WORTH at least a thousand words, but sometimes an unintended interpretation emerges. Such was the case for the illustrations in "Once We Were Not Alone," by Ian Tattersall [January]. Numerous readers questioned the absence of females in the pictures. "Out of six portraits representing various hominid species, all six feature males," observes Giovanni Dall'Orto of Milan, Italy. "This apparently male-only reality made me wonder how our ancestors reproduced." Other correspondents wondered why only Homo sapiens was portrayed as having light skin. "If Neandertals coexisted with moderns in Europe, wouldn't they have been blond, too?" asks Sandy Campbell of New York City.