Controversies
It has been implied that Dixon plagiarized at least some of the designs for the future humans from another illustrator, Wayne Douglas Barlowe. In Barlowe's book The Alien Life of Wayne Barlowe, Barlowe includes a section with sketches that are nearly identical to some of the creatures in Dixon's book. Barlowe asserts that they are from a project that was plagiarized by "another author", declining to name Dixon. In a Usenet thread on rec.arts.sf.written, author Robert J. Sawyer confirmed that Dixon (or Dixon's artist) was indeed the party against which Barlowe had a complaint, as evidenced in the trade press at the time.
Read more about this topic: Man After Man: An Anthropology Of The Future