WALKING WITH THE GREAT APES: Jane Goodall, Dian Fossey and Birute Galdikas by Sy Montgomery (Houghton Mifflin: $19.95; 275 pp.) It is unclear which is a more bizarre variation on human beings: Jane Goodall’s chimps (who share 99% of our genes) or the author and her mentors, the three primatologists warmly portrayed here. Like Goodall, who was fond of sleeping with earthworms under her pillow, Sy Montgomery came to identify so closely with three young emus (flightless birds resembling ostriches) that she followed nearly their every movement for six months, stroking her hair as they preened each other, bursting into tears when she lost sight of them. “I wanted to be with them,” she cries one day, soaked and miserable in a Gigera bush as the rain turns to hail. “But they had run away from me.” Montgomery’s feeling of kinship with these primatologists spares them from the kind of scrutiny applied in recent tell-all biographies (such as Harold Hayes’ reports of Fossey’s drinking and lying), but helps us see why their bonding with the apes was especially poignant: They could not do the same with humans.