The phrase "the appearance of human brains" is ambiguous, as it stands. For example, we may ask, "How many human brains appeared last year?" Of course, we usually use the term "developed" or "grew" in this context.
But they do in fact "appear", if not from nothing, from very little - an invisible speck, in fact. What about the second law in this case? Isn't it an obstacle to this spontaneous appearance of this incredible order? Indeed it is! And the reason it can happen is the continual flow of energy maintained by cellular metabolism.
Well, you might scoff, "The DNA provides the order! the instructions!" Instructions to whom? The DNA is a molecule. Its expression unfolds as a simple thermodynamic reaction. Why doesn't the DNA simply decay or dissipate? Where is the maintenance crew that keeps it going? Why isn't it like the 747 abandoned in the junkyard?
The point is that the unique nature of the spontaneous and undirected processes of life, including reproduction, ought to inform our thinking about the natural history of these life processes on the planet earth.