History Fridge / AfterEarth

* Why would all the animals on Earth evolve to become to the perfect predators for humans when humans left earth? Did that happen before they left? Otherwise, that would be like a deep sea fish adapting to survive elephants. Even leaving aside the hyperbole or ignorance of the statement by Cypher, the flora and fauna of Earth is clearly ridiculously dangerous to humans.
** The above FridgeHorror proposes an answer for how they'd 'evolve to kill humans', given than only some humans managed to escape while the remaining majority were picked off by the predators. Its still stupid, but that's probably the best explanation.

** For that matter, wouldn't a berserker be just as effective as a someone ghosting while requiring much less ability and training? The only pheromone they're cued to is fear, and humans naturally switch from fear to anger if the flight-or-fight response is triggered the right way. Given the movie features a famous Ursa slayer with "rage" right in his name you almost have to wonder if this was a plot point in an earlier version of the script.

** Never mind odor-proof suits or fear-suppression: the whole premise of "ghosting" eliminating the smell of fear-pheromones is garbage anyway, because the "smell of fear" is ''still a smell''. As in, volatile chemicals which can ''linger'' around and on their source, whether or not said source continues to emit them. Just suppressing fear isn't going to make already-released pheromones spontaneously disappear, any more than relaxing after exercise so you cease to sweat will make you stop smelling sweaty from a workout. Kitai should've had to take a shower before he stopped being detectable to the Ursa, because he'd ''already been'' scared by it for a considerable time before he manned up.

** Also, never mind ''hiding'' from the Ursa by suppressing fear: if the things are so single-mindedly stupid that they respond to nothing except one smell, why not '''bottle''' human fear-pheromones by the gallon, and use them to ''bait'' any Ursa that comes along into some mechanized death trap?

%%* The Ursa are not a naturally evolved species. They were created by the alien natives for the explicit purpose of killing humans. The Ursa show no sign of sentience other than [[spoiler:what they do with human corpses, for which the reasons are left wonder if any Ursa have zero fondness for their own creators and would kill many natives if they were to be accidentally set to the imagination]], they respond to containment with aggression, and they also kill non-human creatures. It makes audiences loose in their territory.

* Why climb up a volcano in order to improve the signal, when the enormous ash cloud crowning it is the most likely reason the signal is so poor in the first place? For that matter, why does the beacon need reception at all? It's a beacon, is supposed to ''generate'' a signal. Considering how strong the signal appears to be at the end, it seems unlikely the ash cloud would stop much of it.

** Never mind odor-proof suits or fear-suppression: the whole premise of "ghosting" eliminating the smell of fear-pheromones is garbage anyway, because the "smell of fear" is ''still a smell''. As, in volatile chemicals which can ''linger'' around and on their source, whether or not said source continues to emit them. Just suppressing fear isn't going to make already-released pheromones spontaneously disappear; Kitai should've had to take a shower before he stopped being detectable to the Ursa, because he'd ''already been'' scared by it for a considerable time before he manned up.

As for your point about the corpses, I think that the many lights that were on the map near the start were survivors who didn't die in the crash. Since two lights were right next to each other (Kitai and his father), there were most likely survivors who were hunted won by the Ursa then used to instill fear in any who say the corpses.

** Never mind odor-proof suits or fear-suppression: the whole premise of "ghosting" eliminating the smell of fear-pheromones is garbage anyway, because the "smell of fear" is ''still a smell''. As, in volatile chemicals which can ''linger'' around and on their source, whether or not said source continues to emit them. Just suppressing fear isn't going to make already-released pheromones spontaneously disappear; Katai should've had to take a shower before he stopped being detectable to the Ursa, because he'd ''already been'' scared by it for a considerable time before he manned up.

** Never mind odor-proof suits or fear-suppression: the whole premise of "ghosting" eliminating the smell of fear-pheromones is garbage anyway, because the "smell of fear" is ''still a smell''. As, in volatile chemicals which can ''linger'' around and on their source, whether or not said source has ceased to emit them. Just suppressing fear isn't going to make already-emitted pheromones spontaneously disappear; Katai should've had to take a shower before he stopped being detectable to the Ursa, because he'd ''already been'' scared by it for a considerable time before he manned up.

*** Humans can simply put on an environment suit, and they could be three feet from such a creature and not be detected. How does the creature avoid obstacles? If it uses some other sense to avoid (for example) falling off a cliff, that sense could also be used to detect the human-shaped object next to it.

** Umm... More complex organisms without the ability to sense light live almost exclusively in places where light is scarce (deep sea, caverns etc.) on Earth, from this we can conclude that sight must be a huge evolutionary advantage. Also creatures with just one type of sense are exceedingly rare and even yet: Sensing pheromones is normally a subset of smell, but somehow these creatures are so [[CripplingOverspecialization overspecialized]] in it that just stopping "one" pheromone production (as opposed to all the other scents we also produce) renders people invisible to them? Why weren't these creatures hunted down already? Or better yet how can they survive without bumping into things? (Most stuff (trees, rocks etc.) doesn't produce fear pheromones. Theoretically they could mark / memorize their territory but this wouldn't work outside of it, not to mention how much work it would involve.) How do they mate? They would need to smell other things and/or have more senses to navigate, but those would also make Ghosting less effective (if not break it completely).

* Guns and other projectile weapons apparently don't exist in this universe. There's no reason to come anywhere near an Ursa to attack it. Even a stone age bow or spear would make a huge difference.

* When Cypher asks Kitai what it was that crawled onto his hand (a ''spider''), you might wonder why Kitai doesn't answer the question at all? Maybe it's because he just doesn't care about the situation since he shook the spider off? '''Or''' maybe it's because [[DramaticIrony he's never been to Earth or studied its native fauna, so he has no idea what that thing was]].

* When Cypher asks Kitai what it was that crawled onto his hand (a ''spider''), why doesn't Kitai answer the question at all? Maybe it's because he just doesn't care about the situation since he shook the spider off? '''Or''' maybe it's because [[DramaticIrony he's never been to Earth or studied its native fauna, so he has no idea what that thing was]].