To your point on extreme cold you are correct. I should have wrote low cold tolerance and I will change it. But with that said;Humans have certainly become an alien species on this planet for sure in so much that most all have lost their connectivity to the earth.
They don't need a keen sense of smell any longer.
They no longer use those muscles once needed every day for survival.
The reason we need to watch our diet is because we eat so much garbage and over indulge on it.
If we stopped being lazy gps and maps aren't needed as much as one would think.
Navigating in the night isn't hard, just do it. You'll be surprised, just stay away from any light and things become 'seen'.
We engage in sex for fun because we can.
No we can't take extreme cold without a heat source or protection......and neither can most other life on earth except the few animals that have evolved to that extreme condition like polar bears and penguins but you won't find many others.
Yeh, and skin cancer.........it may have once been one of the factors in the limiting of population numbers. And we're the only animal too stupid to get out of the sun when it becomes to hot and go find some shade. But like most mammals we can not tolerate too much heat and even the reptiles can only take so much before disappearing for cooler places.
Sensing danger is a matter of using all the senses........just like all other animals do. Where our eyes have evolved for a focal length most other primates eyes have evolved for a limited focal range but is fine tuned to detect movement. And smelling danger is a lot easier without car exhaust and fabric softeners blowing out of dryer vents. And hearing danger is sometimes not what is heard but what isn't. And it all comes together for a 'feeling'. For instance, if someone is staring at you from across the room how do you know and turn to look?
Yes we as a species have become the aliens on this earth.
Where we once belonged we no longer are part of.
The question isn't have we become aliens but are we the aliens?
Have we been genetically engineered or are we indigenous to this rock?
If we are then that would mean that we have been here long enough to have evolved as all other species with the same physical abilities and tolerance. The point of contention is the premature transition from homo-erectus to homo-sapiens.
I say premature because the natural evolution of development from one stage to another is estimated to be at least a few million years as opposed to a few hundred thousand years.
In addition, there is nothing in the fossil or archaeological record to this day that shows a direct connection between the two.
Henceforth (missing link)
Now, if we also factor in the sudden and inexplicable acceleration from hunters and gatherers to modern man (homo-sapiens to modern homo-sapiens in an estimated 30,000 to 50,000 years) that leaves one to question if the transition is a natural process or intervention?
Now we can debate back and forth all day about the comparison of human deficiencies as opposed to animal life and go absolutely no where. We agree to disagree.
Here is a link for you. It's about a Zana, who is believed to be Neanderthal or Yeti discovered in Russia 1850 and captured, introduced to modern society and had several children. She is an example of what we would have been like without Genetic Engineering or tampering. Also. I have also included a timeline link which is just one of many to just to show the periods of natural human evolution..
Zana the Neanderthalof Russia
Timeline; Human Evolution