When we think of the uncanny valley, it is usually in terms of blending in, in everyday life; the robot, cyborg, or android looking like an all-natural human in their appearance, mannerisms, speech patterns.
One aspect that is never, or at best very rarely considered in most of these views, is that in order to blend in long-term; to truly feel one of the populace, even if your substrate is not the same as a natural human, there is more to the valley than simply looking, acting human.
It is not a lot of good really having a face, a body which is believably human; has bypassed the uncanny valley, but always stays the same. Subtle side-effects of the valley return when a face, when a body looks the same healthy youthful self, year after year, decade after decade, even century after century. Unless we manage to eliminate ageing from the general population as well, then a being of a different substrate needs to age, to change, to take on the appearance of decay even if not the actuality.
This is what Andrew ? the robot with the desire to be human, in the film ? set out to achieve for himself. In actuality, Andrew went further. He actually developed a technological aging process to put himself trough so that hiss body would wither and die in line with any other human, because he sought to be human himself.
Even if the synthetic being (or even synthetic non-sentient as the case may be) has no such desires, the concept of aging, or the appearance thereof, is a good one. It is an aspect of circumnavigating the uncanny valley that should never be forgotten: No matter how perfectly a human face, behaviour, mannerisms are recreated, unless the face, the body seems to change with time, the uncanny valley has not really been conquered.
Link: Bicentennial Man
Link: Bicentennial Man: Index of Stills
Link: The Uncanny Valley
Link: Large Image Display: The Uncanny Valley