TiS has not yet commisioned a full length treatment of this subject. However, readers may be interested in two comments contained in books reviewed elsewhere on this website. Not all books are so up-front about these problems.
The study of the evolution of modern humans from hominid ancestors is very speculative. Much of our present understanding is based on very little evidence. Only a few thousand hominid fossils have been discovered and most of these are incomplete. Sometimes anatomically similar bones collected over a wide area are assumed to be from the same individual, but they may actually be from different individuals. The following account of hominid evolution does not pretend to be complete or undisputed. It is merely an attempt to bring together some of the information on hominids that has gained general acceptance. (pages 458-459)
The presence or absence of a creative super-intelligence is unequivocally a scientific question...
Richard Dawkins (2006)