Final answer:
The racial approach to human variation has been unproductive and damaging for two main reasons. First, race is a weak construct in biology, with more genetic variation within a racial category than between racial categories. Second, the concept of race itself is not scientifically valid, as genetic markers for physical characteristics do not fully align with racial categories.
Step-by-step explanation:
One reason why the racial approach to human variation has been unproductive and damaging is that race is a weak construct when it comes to biology. After the sequencing of the human genome, scientists discovered that there is actually more genetic variation within a racial category than between racial categories. This means that focusing on race often leads to misdiagnoses and under-diagnoses of diseases. Another reason is that the concept of race itself is not scientifically valid. While there are genetic markers for physical characteristics like skin color, hair texture, and eye shape, only a few of those markers align with the racial categories we use. If we were to change our social constructions and categorize people based on different genetic characteristics, we would have an entirely different set of races.