Hobbits may have evolved from H. habilis

This article has a good description of recent results based on foot structure.  It also has a family tree diagram with Hobbits included. 





Palaeoanthropology: Homo floresiensis: from head to toe : Article : Nature

These features suggest that H. floresiensis evolved from a species that was anatomically more primitive than classic H. erectus from Asia. One possibility (Fig. 2) is that H. floresiensis evolved from H. habilis, whose skeleton is poorly known but is australopith-like in many respects. Another is that H. floresiensis descended from an earlier type of H. erectus, whose body may have been much less modern than we currently credit, and which perhaps deserves a separate species designation (H. ergaster).