Read Lady Churchill's Rosebud Wristlet No. 26 for Free Online Page B

segments instead of three, so it makes more sense to put them in a separate category.
    Folk biology is interesting to anthropologists because misconceptions like thinking spiders are insects are not universal. They vary from one culture to another, and anthropologists can learn things about a culture by the way they think about the biological world. Folk biology is also interesting to psychologists because studying children’s ideas about the natural world gives us some insight into how our cognitive skills develop as we mature.
    As for me, once I read about folk biology, I started to see examples of it everywhere; even when we are scientifically literate, we engage in folk biology on a regular basis, without being aware of it.
    Let me offer some examples of what I’m talking about. At various points in history, people have said that if you wanted a strong body, you should eat meat instead of bread or potatoes. There have been all sorts of justifications for this, but one of them—even when it wasn’t explicitly stated—was the belief that you literally are what you eat. Eating muscles would make your body muscular, while eating soft and starchy foods would make your body soft and starchy. When people advise you to trim the visible fat from meat, they are implicitly using a similar argument: that the layer of fat on your steak will translate into a layer of fat on your body. Part of the skepticism about the Atkins diet was rooted in this; how could you lose weight without reducing your fat intake?
    There’s an obvious flaw in this line of reasoning, which is that cows eat grass but beef isn’t anything like grass. Cows are able to create bones and muscles and fat without eating any of those things, and humans can do the same. There are some competitive bodybuilders who are vegetarians. And the Atkins diet does seem to work; you can lose weight even with a diet high in fat. But the idea that what you eat translates directly into your body is still appealing to us; it’s easy to believe, it makes sense at an intuitive level, it’s something a child could understand. That is folk biology in action.
    Doctors aren’t immune to this, either. For years doctors recommended that we limit our consumption of eggs because eggs are high in cholesterol, as a way of reducing the level of cholesterol in our blood. But more recent studies have shown that this doesn’t actually work. Our bodies make cholesterol out of saturated fats, so you can have high blood cholesterol even if your diet contains no cholesterol at all. But the reason that doctors told us to eat fewer eggs was that, at some level, they still believed that you literally are what you eat. They were engaging in a kind of folk biology.
    Now, it’s true that some of what happens in our bodies can be understood in a simple mechanical way. But that fools us into thinking that everything in our bodies can be understood in the same way, which is what gets us into trouble. Because the reality is a lot of what goes on in our bodies is opaque. A lot of biology is highly non-intuitive, and can’t be understood by making analogies with mechanical systems.
    Let me give one more example. We have blood flowing through our circulatory system. And when you’ve lost a lot of blood, replacing the missing fluid with someone else’s blood can save your life. That makes sense, intuitively. If your car’s engine is running low on motor oil or brake fluid, you can add a quart and get it working again. However, you cannot simply take blood out of one person and put it into another person arbitrarily. Doctors have tried that, and it didn’t work. It turns out that people have different blood types, and they aren’t compatible. And it’s not even the case that you can only transfuse blood between people with the same blood type; it’s actually more complicated than that. To understand who can donate blood and who can receive it, you need the concepts of antigens and antibodies, which