Please answer a question about the following article about Race (human categorization):

Morning (2008) looked at high school biology textbooks during the 1952-2002 period and initially found a similar pattern with only 35% directly discussing race in the 1983–92 period from initially 92% doing so. However, this has increased somewhat after this to 43%. More indirect and brief discussions of race in the context of medical disorders have increased from none to 93% of textbooks. In general, the material on race has moved from surface traits to genetics and evolutionary history. The study argues that the textbooks' fundamental message about the existence of races has changed little.

What does the study argue about the fundamental message regarding the existence of races?
changed little