History Headscratchers / AfterEarth

*** The giant bird doesn't bother to incapacitate Kitai all that much to feed to her young, the panther is more interested in the baby birds than Kitai, and the monkey only really gets going after Kitai throws rocks at it. Honestly, "Everything evolved to kill humans" rings pretty hollow when the only creature that goes out of it's way to attack Kitai on it's own is the river parasite and even after poisoning him it's non fatal.

*** But that planet's atmospehere is apparently toxic to humans... somehow, see the next point below. Regardless, if it's an unsolvable problem then why would they need any other deterrent? And if it was solvable then why ''wouldn't'' any of the humans want to resettle their home planet?

*** Maybe is the exact opposite; the planet has too much oxygen, after all they do live in a planet with maybe less oxygen and/or ships with limited oxygen so they get sick for so many oxygen. Silly, but the movie has many problems anyway...
*** If anything the more logical explanation would be that it's Nova Prime that has more oxygen and over the centuries humans adapted to that level, it's like comparing people who live at sea level to those who spend all their time in the high mountains, swap places and until they adapt the former will be easily winded while the later has seemingly boundless energy. Kitai probably would have acclimated given enough time that they didn't have.

* Where on Earth (literally) are these folks? Did they crash land in an old national park? According to the backstory we took over MORE of earth after the time this movie came out - where are all the ruined cities, etc? Not even a little piece of junk sitting around!

** Going by the cave paintings in one scene and overall area, I would say somewhere in Europe, seeing as those particular cave paintings looked familiar as the ones in either France or Spain.

** That and there are plenty of green projectiles that evidently no one uses. If they're already going to regress to using sharp sticks, why not use bows too? With their technology it'd be pretty easy to make a sort of preloaded multi shot crossbow side arm with toxic arrow heads.

* I guess animal life could use the same geothermal hotspots that Kitai uses in tbe movie, but how do plants from a tropical forest survive being frozen solid every night?

*** Or race up a mountainside full of ''molten lava pools'' without getting roasted, for that matter? Kitai himself had to jump or scramble past several of those on his way up the volcano, yet a creature that can't ''feel'' evidently sidestepped them all.

*** Or race up a field full of ''molten lava pools'' without getting roasted, for that matter? Kitai himself had to jump or scramble past several of those on his way up the mountain, yet a creature that can't ''feel'' evidently sidestepped them all.

** On a related note, if the Ursa can so eaasily sense humans by smelling their fear-based pheromones, how come Kitai stopped smelling afraid when he calmed down after having been terrified? Does calming down magically make the already-secreted molecules in his bodily secretions instantly disappear? Also, how the heck could the thing track him ''underwater'' in the caves?

*** Maybe is the exact opposite; the planet has too much oxygen, after all they do live in a planet with maybe less oxigen and/or ships with limited oxygen so they get sick for so many oxygen. Silly, but the movie has many problems anyway...

* If the Ursa sense fear, and ''only'' fear, why not combat them with machines? Present-day Earth has all sorts of unmanned machines of war, including drones and aircraft that mean humans don't have to be anywhere near the battlefield. A thousand years into the future, this technology should be far more advanced...and yet all we see of the war in the film is sparsely-armored infantry being tossed into the jaws of the Ursa. We even see later in the film that this society has access to advanced drone technology.

** The movie was filmed in Costa Rica, if that worth something.

** On a related note, if the Ursa can only sense humans by smelling their fear-based pheromones, how come Kitai stopped smelling afraid when he calmed down after having been terrified? Does calming down magically make the already-secreted molecules in his bodily secretions instantly disappear? Also, how the heck could the thing track him ''underwater'' in the caves?

** [[WildMassGuessing My personal theory]] is that he was riling up his son on purpose so he could be at his physical peak and do the jump; if you notice in that scene he looks at Kitai's vitals twice and notices his heartrate going up.

*** Maybe it ''can'' smell him but doesn't have the brains to figure out that that's what humans actually smell like? Why ''that'' would be is its own question, though, as the Ursa is obviously fairly intelligent, and even animals as simple as ''wasps'' [[http://en.wikipedia.org/wiki/Hymenoptera_training can be trained to associate a novel scent with food]]. Perhaps the toxic air constantly smells like a sweaty human, making fear the only difference between a human and the air around him?

** To be ''that'' human-specific, it'd have to be an omnipresent contaminant in the air that selectively targets biochemical processes unique to humans, like maybe a human-specific antigen in erythrocytes; the contaminant would adhere to them each time it's inhaled, and gradually shut down their oxygen-delivery. Which would pretty well ''guarantee'' it was engineered, not random.

** To be ''that'' human-specific, it'd have to be an omnipresent contaminant in the air that selectively targets biochemical processes unique to humans, like maybe a human-specific antigen in erythrocytes that impairs their oxygen-delivery. Which would pretty well ''guarantee'' it was engineered, not random.