Somebody asked this question on Reddit. The full title of their question reads:

I want to explore these questions and I'm unsure where to turn to for resources: How is [it] that our own brains are "black boxes" to us? How can we (and other animals) evolve yet be unaware of our own evolution? How are we not able to understand how our own bodies work?

They follow up with additional questions. Below are quotes and my answers.

You get at some deep questions about evolution and epistemology. Let’s go over them one question at a time.

How can animals operate due to biological complex mechanisms that they are unaware of and/or unable to understand?

Well, you can operate a calculator even if you don’t know how to build one, right? You are using Reddit even though, presumably, you don’t know how to make websites. The same principle applies to animals: their genes give them all the instructions necessary to operate their bodies. Animals are a much simpler case than humans because they execute these instructions mindlessly, like robots; purely zoological explanations apply for their behavior, which is itself caused by animal genes. But even in humans, people tend to overestimate what kinds of behavior require conscious awareness.

As a part of evolution, shouldn't our own awareness of evolution and our bodies be commensurate with the evolution we experience?

It would certainly help if evolution had given us that knowledge, but genes that don’t code for it still manage to spread, so they don’t code for it.

In other words, as we evolve, shouldn't the knowledge of our own evolution keep pace so that the knowledge we require to maintain our health and integrity is known to us?

The knowledge that creates our bodies and determines its functionality is stored in genes. Our minds have no default visibility into our genes or really any of the resulting software we inherit, so this knowledge isn’t conscious.

Genes contain the knowledge required to maintain health and integrity for all viable organisms except humans. (In most cases, it’s just enough knowledge for organisms to barely scrape by.)

For humans, things are a bit more complicated – but also more fascinating and wonderful. Humans are creative. They are the only animals capable of creating additional knowledge during their lifetime. Roughly speaking, this ability shifts selection pressure from our genes to our minds. That’s why we don’t know how to walk from birth even though many other animals do: when human genes coding for the ability to walk underwent disadvantageous mutations, humans could make up for those mutations during their lifetime by either learning to walk themselves or by making a cane, say. So the genes continued to devolve over time and humans picked up the slack.

Shouldn't evolution dictate that if we are to survive — we need to know how to survive and maintain our bodies? And to maintain our bodies, we need to know our bodies? i.e. how they work? how to maintain them optimally, etc.?

Now that selection pressure has shifted, evolution does dictate, in a way, that we understand our own biology to survive. At least until we upload our minds to better machinery. So in the long run, our biology is just a parochial factor.

There’s one thing I noticed about the last question in your title, “How are we not able to understand how our own bodies work?” But we are. Animals aren’t, but we are. We have doctors and nurses who understand a great deal about our bodies.

More generally, your questions sound a bit like you think evolution is goal directed, or should be. It’s not. Evolution has no concept of what might benefit organisms. Mutations happen without regard for the problem situation any particular organism might find itself in. Evolution is a phenomenon involving imperfect replicators (genes, in biological evolution), some of which spread better than others. If a replicator undergoes a mutation that causes it to spread better today and go extinct tomorrow, evolution will still favor it.