Final answer:
It is true that there is greater genetic variation within traditional racial groups than between them, because the concept of race is not supported by biological evidence. Traits like skin color vary along a spectrum, and racial categorizations fail to accurately represent human genetic diversity.
Step-by-step explanation:
The question addresses genetic variation in humans and the scientific invalidity of traditional racial categorizations. It is true that there is much greater variation within each of the traditional so-called races than between them. This is because the concept of race does not have a biological basis, and a vast array of human genetic diversity cannot be adequately or accurately divided into racial groups.
For instance, the genetic markers that determine visible traits like skin color and hair texture—which have traditionally been used to categorize races—are few compared to the many thousands of genetic markers each person has. Therefore, the biological approach to race shows that any such racial categorization fails to capture the true extent of human genetic diversity.
Biological anthropologists have demonstrated that traits vary along a spectrum, with more genetic variation existing within so-called racial groups than between them. Hence, the focus has shifted towards understanding human diversity through the lens of ancestry rather than the outdated and scientifically unfounded notion of race.