I will tell you about a conjecture by Griffiths and Harris from 1985 concerning the degree of curves on 3-dimensional hypersurfaces, and how this conjecture is related to the failure of the integral Hodge conjecture for these varieties. I will then explain how to prove some cases of their conjecture using a degeneration technique by Kollár, and how to generalize this result to higher dimensions. Finally, I want to end with some open questions.