If by modern man you mean homo sapiens, you will get varied answers.
A phylogeny is the family tree of any species, traced back through geologic time until reaching the theoretical common ancestor of all life.
To understand why it is difficult for scientists to name a species' parents, grandparents, etc. in direct descent is that we study animals not along a line with us. We are similar to chimps but did not evolve from them. Think of the primates as being close not on the same limb of a tree, but at the ends of several different limbs which land us in fair evolutionary proximity.