responsible
Explanation
The Joke
A scientist presents a graph showing the relationship between power and responsibility for humans over time. The graph reveals that while power has increased exponentially (through technology, weaponry, etc.), responsibility has remained essentially flat. The scientist explains that for every civilization in the universe, there is a critical point — around 4,295 on his scale — where power vastly outstrips responsibility, and at that point the civilization destroys itself. The implication is that humanity is approaching or has reached this threshold.
In the final panel, someone in the audience asks the natural follow-up: "Wait, if this happens to every civilization, what are you doing here?" The scientist nervously admits he is "from a civilization at about a 2.5," meaning his own species never developed enough power to be dangerous — they are safe precisely because they are relatively weak and primitive compared to the civilizations that destroy themselves.
The Humor
The joke turns on a clever inversion of the typical alien-visitor trope. Usually, aliens who visit Earth are imagined to be far more advanced. Here, the alien scientist is from a civilization that is less powerful than humanity — he is not a representative of a superior race but rather a survivor from a mediocre one. The civilizations that got powerful enough to be impressive all blew themselves up. It is a darkly funny commentary on the Fermi Paradox: the reason we do not see advanced aliens is that advanced civilizations self-destruct, and the only ones left to study the phenomenon are those too underdeveloped to have the same problem.
References
The comic references the Fermi Paradox — the apparent contradiction between the high probability of extraterrestrial civilizations and the lack of evidence for them. It also alludes to the famous Spider-Man dictum "with great power comes great responsibility," inverting it to suggest that in practice, the two do not scale together at all.