evolution-6
Explanation
The Joke
The comic contrasts "How People Think Evolution Works" with "How Evolution Actually Works." In the top half, a butterfly is being eaten by a bird and dramatically declares "Karate!" as if it could willfully evolve a defense mechanism -- the implication being that people imagine evolution as a conscious, directed process where organisms choose to become stronger or faster in response to threats.
In the bottom half, "How Evolution Actually Works" shows the same scenario of butterflies being eaten by birds, but instead of a heroic self-improvement montage, many generations later the surviving butterflies have simply become cancerous-looking blobs. The butterfly says something like "I'm cancerous-looking so birds find me repulsive -- I am the pinnacle of nature." The point is that evolution does not optimize for elegance or strength; it just selects for whatever random mutations happen to improve survival, even if the result is deeply ugly or inelegant.
The Humor
The comedy comes from deflating the popular romanticized notion of evolution as a process that creates sleek, powerful, optimized creatures. In reality, natural selection is driven by random mutation and differential survival, and the "solutions" it arrives at are often bizarre, ugly, or counterintuitive. The butterfly proudly declaring itself "the pinnacle of nature" while looking like a horrifying blob is the punchline -- evolution's results are effective but rarely glamorous.
References
This comic plays on a common misconception about evolution known as "Lamarckism" -- the idea that organisms can will themselves to develop traits in response to environmental pressures, as opposed to the Darwinian mechanism of random variation and natural selection.