Fukuyama's reasoning represents a prominent strain of thought about human enhancement, and one that I find doubly fallacious. (Fukuyama is aware of the following criticisms, but neither I nor other reviewers were impressed by his attempt to defend himself against them.) The idea that the status quo represents some “essential” quality of humanity collapses when you zoom out and look at the steady change in the human condition over previous millennia. Our ancestors were less knowledgable, more tribalistic, less healthy, shorter-lived; would Fukuyama have argued for the preservation of all those qualities on the grounds that, in their respective time, they constituted an “essential human nature”? And even if there were such a thing as a persistent “human nature,” why is it necessarily worth preserving? In other words, I would argue that Fukuyama is committing both the fallacy of essentialism (there exists a distinct thing that is “human nature”) and the appeal to nature (the way things naturally are is how they ought to be).