No spoiler here, just philoshopical considerations... What makes a human "human"? Since we think and speak, traditionally has been accepted that people is human as long as there is some level of intelligence and communication skills. Obviously, people sharing the same culture and language can communicate better and thus we can relate easily with them as being humans. Not so easy when others are alien to our own culture and use a different language not readily undestandable to us, but eventually -if you mantain an open mind- can attest that they show some kind of intelligence and communicate between them, so we expand our definition of human to englobe them too. Once you get this far, is not too farfetched to imagine that there may be other forms of intelligence not closely related to us as Homo sapiens: precisely the reason why hunting whales and dolphins have become political incorrect for most countries: we can't really undestand what whales and dolphins are thinking, BUT they show intelligent behaviours and highly coordinated group actions when fishing, for instance. So we can safely assume they are intelligent and communicate among them. We also don't have a precise definition of what intelligence is, though it can be showed that intelligent organisms display highly abstract goal oriented actions: looking at a footprint may produce clues as what animal produce it, in which direction it moved and how long ago that happened. It can be argumented that simple animals may not have this amount of abstraction: either the predator is within their sensorial range and thus exists as a threat or it doesn't. On the other hand, an intelligent animal may perceive the footprints as a real threat because they can establish a link between the present and the future (the tiger is not here right now, but it MAY come back). In FO4, some NPCs are designed to act with some degree of intelligence and can communicate abstract ideas. Hence, it is not farfetched to assume that they are something more than "mere" machines. It is up to each player to determine if the term "human" can or can't be applied to other entities unrelated to our own kind.