Robots
Captain America: He [Ultron] keeps building bodies.
Tony Stark: Person bodies. The human form is inefficient. Biologically speaking, we're outmoded. But he keeps coming back to it.
Black Widow: When you two programmed him to protect the human race, you amazingly failed.
Bruce Banner: They don't need to be protected. They need to evolve. Ultron's going to evolve.
Did you catch that? Not only was that the worst use of an adverb in the history of cinema ("amazingly"?!—come on, BW), this little exchange highlights another potent symbol in Age of Ultron: the robot.
Robots have been with us for centuries, but they're still pretty strange when you think about 'em. The majority of them take human form, only they're meant to do things with their technology that humans can't possibly achieve—like watch an entire PBS telethon without nodding off. (We kid; we love you, PBS.) At the same time, Tony has a great point here: we keep making robots to look like us. Why?
Like Stark says, we aren't the fastest or strongest forms on the planet. We only have our giant brains (relatively speaking) to make us stand out. In the same way, that's also what makes robots stand out. When they appear in people form, they are in some way an expression of a better version of ourselves. They don't get tired; they don't get distracted; heck, they don't even get hungry. In making robots, then, are we fantasizing about superior versions of ourselves?
Ultron sure as heck is. Remember how he got his start? At first, he's just kind of a formless entity, but pretty soon he builds himself a body. Yeah, it's not awesome. In his defence, U. was only like ten minutes old, and he didn't have a lot of material to work with. One thing's for sure, though, he chose to take the form of a human being—albeit a human being with some raggedy limbs and a severe posture problem.
Don't worry, though. Ultron's on a strict self-improvement plan. After he snags the vibranium, he's out to build a better version of himself in Dr. Cho's cradle. Interestingly, this device layers organic material over the titanium frame, creating a true cyborg—part machine, but also part human(ish).
But why not go full machine? Isn't Ultron all about wiping us nasty, brutish humans off the planet? Why would he bother to stay with the human figure at all? Why not a giant, flying robo-ball, or how about a fun-shaped robo-rhombus?
If we listen to Bruce Banner (and we should, unless he turns green and smashes us to a pulp), Ultron is all about evolution: both his own and humanity's. It seems like he wants to embody that evolution by creating the ultimate human-machine hybrid. And we're right back to founding idea of robots in the first place: humans perfected by technology.
Is the idea so far-fetched? In an age of "body hacking," where people have taken to upgrading themselves with technological implants, Ultron seems less a crazed robot and more a reflection of these modern times. (Source) As the robot-in-chief, he shows us one possible (and increasingly real) future for our evolution as a species. At the same time, his example also gives us pause. Is this the route we really want to go down?
As usual, it's up to us so supply the answers. Ultron and this robo-friends do a great job of posing the questions, though. Thanks, big guy. Or should we say, "U. da man"?