That seems a pointless thing to want to hold onto. So what if they are whatever arbitrary definition makes them "human"? Who is this man with such firm beliefs that people should not be allowed to improve?

If they can laugh, cry, love, and hold wonder and friendship in their hearts why should they be confined to things like short lifespans and old age, the anxiety that comes with the march of time for mortals, if you had the ability to remove it?