Question

A scientist recently stated a claim that it is unlikely that the inability to roll your tongue will disappear from the population. Provide reasoning to explain how evidence supports the scientist's claim.

Answer 1

Some people can curl up the sides of their tongues to form a tube shape. In 1940, Alfred Sturtevant observed that about 70% of people of European ancestry could roll their tongues and the remaining 30% could not.

Many sources state that tongue rolling is controlled by a single gene. However, as Sturtevant observed, people can learn to roll their tongue as they get older, suggesting that environmental factors—not just genes—influence the trait. Consistent with this view, just 70% of identical twins share the trait (if tongue rolling were influenced only by genes, then 100% of identical traits would share the trait).