Promotion and demotion in science
Scientists have promoted and demoted things like viruses and planets throughout the ages. At one point, the virus was considered to be a poison or a non-living thing: merely a rather large and complex organic molecule. Later, scientists promoted it to a sort of living thing, or at least in the gray area between living and non-living. Likewise, the lights in the sky which moved relative to the others were at first called stars but later classified as planets (not sources of light, but reflecting the light of the Sun); one of these, Pluto, was famously demoted to a dwarf planet in 2006 (see Kuiper Belt).