In recent news, the discovery and analysis of some five skulls in Dmanisi, Georgia has yielded new data about the number of ancestors on our family tree.
One skull appeared to be quite different than the others, but after measuring the dimensions of all of them, the scientists determined that the dimensional variation was not very different than that found among humans. This lead them to analyze other fossil hominids and they found out that most other discoveries fell within the dimensional variation of homo erectus, as had the 1.8 million year-old Dmanisi finds.
This means that some of the branches on our family tree may not be a separate species.
Again, the paradigm shifts to accept new data.
Have a great day.