Final answer:
Brigham's testing did not conclude that recent immigrants were more degenerate. The perception of recent immigrants as degenerate was fuelled by nativist groups and prejudices based on cultural differences.
Step-by-step explanation:
Brigham's testing of immigrants in the U.S. did not lead to the conclusion that recent immigrants were more degenerate than those before them. The perception of recent immigrants as being degenerate was fueled by nativist groups and prevalent prejudices at the time. These prejudices were based on cultural differences, such as religion, language, and appearance. Immigrants who spoke unfamiliar languages, practiced unfamiliar religions, and had different customs were seen as a threat by many established city dwellers. This discrimination was a result of fear and ignorance rather than any scientific testing or evidence.