It could be less specific than that. Anything can be uncanny and off-putting if it's slightly different than what we expect it to be. It might not be a specific reaction to seeing deformed human faces, but just the general reaction to something we expect to look familiar looking "wrong".
Nature is full of camouflaging organisms, so it could be that: a strong aversion instinct to camouflaged things which can be threatening. False-eye camouflages give me a similar uncanny valley feeling to androids.
Could also have to do with rejecting deformed offspring like others have mentioned.
Rejecting deformed, sick, or injured people was certainly not universal. There's a very, very old skeleton of a person who had severe congenital deforimities and was likely unable to walk any real distance. This was at a time when humans were semi-nomadic as a rule. But she lived to, at the very least, be an adult (determining age from skeletons is tricky). This implies that her community carried her and brought back food for her when foraging her whole life, despite her being "unfit". She also had several cavities, something that was very rare at the time. We'll never know, but a few people have suggested that perhaps her friends and family were bringing her honey they had foraged, that she would be unable to acquire herself.
It could be less specific than that. Anything can be uncanny and off-putting if it's slightly different than what we expect it to be. It might not be a specific reaction to seeing deformed human faces, but just the general reaction to something we expect to look familiar looking "wrong".
Nature is full of camouflaging organisms, so it could be that: a strong aversion instinct to camouflaged things which can be threatening. False-eye camouflages give me a similar uncanny valley feeling to androids.
Could also have to do with rejecting deformed offspring like others have mentioned.
Rejecting deformed, sick, or injured people was certainly not universal. There's a very, very old skeleton of a person who had severe congenital deforimities and was likely unable to walk any real distance. This was at a time when humans were semi-nomadic as a rule. But she lived to, at the very least, be an adult (determining age from skeletons is tricky). This implies that her community carried her and brought back food for her when foraging her whole life, despite her being "unfit". She also had several cavities, something that was very rare at the time. We'll never know, but a few people have suggested that perhaps her friends and family were bringing her honey they had foraged, that she would be unable to acquire herself.
Also we used to put the Hapsburgs in charge of things