First of all, our earth's atmosphere(and gases) as you think is not really a unique one. Lot of planets share the same kind of atmosphere and same composition of gases. The concept of global warming due to green house gases and depletion of ozone is one of the greatest jokes ever. Our atmosphere is never gonna get affected by greenhouse gases, factory emmisions, pollutants etc etc. Please refer to this link: http://news.nationalgeographic.com/n...s-warming.html
Let me go one step further and give you a big big surprise(if you can handle it) - Our atmosphere was "created" by 8th dimensional beings. We are being protected from a lot of external radiations, comets, asteroids etc etc because of this. Not only that, our atmosphere is still being repaired by these "beings" to shield us from Sun's increasing radiation. All this heat waves that we experience now is due to the heating up of sun. Sun is getting reallly hot every month. And this has absolutely nothing to do with global warming.
And coming to the uniqueness of humanoid, let me tell you that we are not only being visited by humanoid aliens but also 'Orbs', 'light beings' and other disgusting looking extraterrestrials. Humanoids are coming from other earth-like planets with earth-like atmosphere, nonearth-like planets with exactly the same atmosphere. Earth's atmosphere(shield) is designed by higher intelligence and not by random nature.
There is one big leap between homosapiens and neanderthals. Our scientists could never trace out this missing link, and never will because we are here as a result of dna manipulation done by the Reptilian Aliens. Our darwinian evolution chart can not bridge this gap with pieces of bones bcos ther ain't any.
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