I want to know the answer to the following question:
How were older notions of race used?
All the background I'm provided with is that "As another example, she points to work by Thomas et al., who sought to distinguish between the Y chromosomes of Jewish priests (Kohanim), (in Judaism, membership in the priesthood is passed on through the father's line) and the Y chromosomes of non-Jews.". Is that enough to answer the question?
Answer: no