how-3
Explanation
Aliens observe Earth and ask "But then how do they have spacecraft?" The answer reveals that humans are fragmented: different groups do small parts of the design, subcontractors handle components, and the people building the rockets "don't even know how the whole thing works -- that's a vague different set of humans." One alien notes that propulsion engineers "don't even necessarily know how the computer works, and the computer is controlled by code that has its own humans, and the code language was built by other humans." There are even teams who "think about spacecraft safety but know no actual engineering." The aliens conclude: "There is no leader. They don't even have a single spacecraft-making entity. It's a bunch of organizations with internal budgets, competing goals, and egos, that don't communicate." When asked what to do, the alien says "Quarantine. We don't need it spreading, but it's too interesting to annihilate." The final panel shows aliens watching Earth like a nature exhibit, with one noting "the passengers don't appear to wonder how they're in an airplane, but in an illusion."
The comic takes an alien's-eye view of human civilization's division of labor and specialization, treating it as something bizarre and incomprehensible. The joke is that our technological achievements (like spacecraft) look miraculous until you realize no single person or organization actually understands the whole system. The aliens' confusion satirizes how genuinely strange it is that humans accomplish complex feats through fragmented, poorly communicating bureaucracies rather than through unified understanding. The quarantine punchline suggests that human civilization is like a weird organism that is too fascinating to destroy but too dangerous (or contagious) to interact with. The final observation about airplane passengers not questioning how flight works drives the point home: humans routinely benefit from systems they do not understand and do not even bother to question.