There are some disturbing reminders to be found here…or perhaps revelations, depending on what you brought with you when you arrived. One is that the human body is not a remarkably well-designed machine. But enough of them work well enough and long enough to reproduce, which is true of all life. That’s all it takes to be successful. That’s why we’re here. It’s why our species is not yet extinct. But the main point in this book is not the flaws in our biology, it’s the state of our knowledge about it. That’s the big revelation. We’re a curious species, and we’ve learned much, often accidentally or despite ourselves. There is no doubt that our discoveries of vaccines and antibiotics have saved countless lives. But it’s disturbing how much medical science does not understand, how many of our standard treatments are not overly effective. Unlike just a couple short centuries ago, you’re now better off seeing a doctor when you’re sick than you would be to avoid them like the plague, but there is still a very good chance they won’t know what caused your illness or how to cure it. And it’s not just because our understanding is imperfect. Our bodies are what they are. They work well enough, long enough, and that’s about all you can expect from them. Trying to get them to remain healthy for a century or more is like trying to fly a Model T Ford to the moon. It’s ain’t designed for that. Unlike the Ford, it’s not designed at all, and there are some things that don’t make much sense. But if you take care of it, you can may be able to get it to run a bit better and last a bit longer. Don’t expect much more from it, though.