Scientists are tantalizingly close to learning just what genetic changes distinguish modern humans from Neanderthals.

Do you think in the above sentence that 'learning' should be changed to 'learn'?

If not, what is your grammmar reason?

Thank you
No hits for "close to learn" at the New York Times.
Use "learning."
to be close to sg. Yes, a gerund is correct there
Students: We have free audio pronunciation exercises.
Using 'learn' instead of 'learning' is wrong. Here the noun 'learning' means the act/process of gaining knowledge.
 Marius Hancu's reply was promoted to an answer.