Just been watching that naff movie with Anthony Banderas as Ahmad ibn Fadlan who goes with a group of Vikings to do battle with the Wendol.
In my opinion a hugely underrated movie.
Adapted from the Chrichton story “Eaters of the dead”
It got me thinking and not for the first time if (bear with me here ) the tales of Trolls and giants of lore could be first hand reports of human-neanderthal interaction.
We know that our two species lived together at one time and even you and I have a few drops of neanderthal blood galavanting around.
There is the theory of the Uncanny valley, it´s where we feel uneasy at the sight of things, humanoid robots for instance, almost but not quite entirely unlike human features.
Why did evolution deem it necessary to develop this uneasy feeling if there was no reason to do so.
Perhaps the boogy man was real at some point in the collective history of our species.
Cannabis is legal now in Germany, eih? You got more than 3 plants? 
Sorry, I don’t know the movie - is it naff or underrated? You seem indecisive.
It bombed at the box office, but I like to watch it every few years or so.
So who’s the neanderthal and who’s the homo sappiens in the movie?
You will just have to watch it and find out.
It makes sense that we feel distressed by the view of corpses (human but not fully human) for two reasons. The thing that killed the now corpse may still be there, that thing can be a bear, a venomous snake or cholera. And, decomposing bodies are a literal vector for diseases.
BAck to the movie, i think I watched it during a long flight. Half-sleep, half-drunk…did not trigger anything to keep me awake 
That is the theory for one reason we have the uncanny valley.
Another one is that we feared attacks from creatures that looked almost like us but they were not human so we developed the the instinct to be afraid and fear anything that looked similar to us.
If you spin this further it could be a reason why racism exists.
Until a few centuries ago the “creatures that looked almost like us but they were not human” were the people from the valley on the other side of the mountain, city-states and all that.
At some point, nations arise and “the creatures that looked almost like us but they were not human” are the people on the other side of a border a little further away.
The current EU experiment is pushing the border for “creatures that looked almost like us but they were not human” a little further to the outside.
These days, as long as people shares some basic values (integration) we/they are not seen as “the creatures that looked almost like us but they were not human”.
From this perspective, racism is a tool to identify and deal with social hazards. But, as human adults, we must be the masters of tools, not let the tools take control of us. So, if the people living on the other side of the mountain are not a hazard, no need to be racist. If the people on the other side of the border are not a hazard, no need to be racist. If the immigrants integrate more or less well, no need to be racist.
Well, there is no need to start building the ideas from zero (movie + Uncanny valley). Maybe read first about Moral circle expansion in the wiki. Something that even people in Ancient Greece discussed AND left evidence of the discussions. Maybe other people in Asia thought about the same but I know nothing about it.
Anyway, the only difference is that this Moral Circle thingy is about empathy and not primitive fear, but it addresses the same old question: were to put a line for worries/empathy/safety?
Women, speakers of other language, humans that look different, humans from the future (descendants), humans from the past (ancestors), animals, plants, the environment, imaginary friends/gods. Lots of things can enter and leave our moral circle. If they’re outside, they’re quite probably a cause of fear.
Interesting, but morals are subject to nurture and not nature and they are as diverse as fashions around the world are and just as fickle as hem-lines on a skirt.
It is only the last few decades that we as a species are beginning to realize that we are global creatures and for now this realization is prevailing only among a few people with the right background, the rest don´t really care.
The link you posted about the moral circle expansion would allow for other members of our family tree, like apes, chimpanzees and Bonobos for instance to have human rights. Eventuel even any creature that is self aware could be granted these rights.
But if there is a link between the uncanny valley and racism, then why did we develop the need to be wary of strangers?
Mmmm, because we need to be wary even from family?
These days we talk about domestic violence, but not long ago around here women and children were a property such as a cow. In other places around the world, that has not changed.
And that’s family that due to some hormones they get triggered into a minimum of empathy. People from the village across the river or a mountain care even less. The ones from the other tribe or nation see slaves/property.
Still wondering why we evolved to be wary of strangers?
This is not paranoia. This is just taking responsibility that there might be a rabid dog within our moral circle and it’s our duty to detect it and neuter it.
Of course, there’s animal, plants, the Earth and deities/imaginary friends.
But, int the section “claimed expansions” you’ll also find humans of other genders, humans of other ethnic groups, future and past people.