Final answer:
Stephen J. Gould found biases in Samuel Morton's cranial measurement research that affected the scientific validity of his conclusions on racial intelligence hierarchy.
Step-by-step explanation:
Stephen J. Gould realized that Samuel Morton's work on crania measurements was flawed due to biases that influenced his data collection and interpretation. Morton had claimed that skull sizes were different among the races, supposedly proving a hierarchy of intelligence, but Gould found that Morton had likely allowed his racist biases to affect his scientific inquiry. This discovery was part of a broader discussion about scientific objectivity and the influence of cultural and personal biases on scientific research.