访谈录 Interview 2007-02-09&11, 生病也是一种需要吗？

Can wearing sun glasses make you more vulnerable to sunburn? Are there people who can resist the AIDS virus better than others? Can a human body rust 1 to death? In his new book Survival of the Sickest, a Medical Maverick 2 discovers why we need disease. Sharon Moalem explores these and other medical mysteries.
Sharon, nice to see you, good morning. Let me dare say, you are an evolutionary 3 biologist and a neural 4 geneticist. (that's right)What is that and why does it make you look at things from different points of view.

Sure. Well, the evolutionary biologist part, it allows me to understand how our ancestors essentially 6 influence who we are today. So whatever they experienced, be, a plague or a climate change, they adapted, and they survived, and they passed down those adaptations to us if it’s skin color or a disease.

So let’s take a look at this question of “is it possible for people to actually rust to death?” medically speaking, is it possible?

Yes, thank you for asking that question. Ah, it is. Over a million Americans might be at risk from too much iron. And what happens is if your ancestors are from Western or Northern Europe, this protected you against the bubonic plague centuries ago. But today you absorb too much iron from the diet, and it essentially gets into certain organs and over time it can rust them. So if it’s in the liver, it can cause liver cancer.

It’s called hemochromatosis.

Right.

You actually suffer from this. (Right) So, this, and the treatment for this sounds a bit barbaric.

It’s, well, it’s amazing actually. It’s a blood donation, a simple blood donation.

But it’s basically bleeding someway. (Right) Well, you’re getting rid of the iron-rich blood, so that it can build up slowly again over time.

Right.

Alright. The second idea, sun exposure, dermatologists 7 everywhere are gonna be freaking out when they hear this, because they say “stay out of the sun, no matter what”. And you say “a certain amount of sun exposure actually can make us healthier”.

Right, so, em, we essentially, we need vitamin D, so we evolve to convert cholesterol 8 into vitamin D. Those are a few steps to get it and Vitamin D is not just good for the bone, it’s good for the immune system. So take African-Americans for example, who live in the northeastern United States, they're at higher risk for prostate cancer than their cousins in Florida. And the reason for this is, they don’t get enough sun.

And another example, this cholesterol levels in people tend to go up in the winter.

That’s right.

Because you’re not breaking down the cholesterol into vitamin D in the same levels.

Exactly.

Alright. But this is very individual. This is not you shouldn’t just tell everybody “go out and get in the sun”.

Oh, no, no. And again this is an example of, of an evolutionary compromise. You shouldn’t get too much sun, but you still needs, you still need the sun.

You talked about evolution. You talked about genes 9. And there’s an interesting point you make in the book. If a disease is a disadvantage to survival, in other words, it promotes premature 10 death, then these people live shorter amount of time, they are less likely to reproduce. Why wouldn’t the gene 5 disappear over time?

Right. Because it has to be protective and essentially that’s the way the iron overloading 11 condition works. It protects. It protected the people in the past from the plague and it still fought to protect people today.

How about this one? Wearing sunglasses increases the chance of sunburn. And this is true?

Right, this is fascinating. So, our eyes sense sunlight and once they do, they produce a hormone 12 that gets the skin kick started to start the tanning process. And by putting on sunglasses, you are short-circuiting in that process. So you shouldn’t go out into the sun, of course without eyewear, eye protection, but take it off for 10 minutes.

So just in 10 minutes, (Right) you can promote the production of that hormone and protect yourself from burning.

Right, you’ll start tanning.

And by the way, we have had researchers; kind of our producers going and looking. And there are medical studies that back all these things up. Organic vegetables are always safer. True or false?

False.

Why?

Plants can’t run away when someone comes to eat them. So they’re great at chemicals and they make poisons. And an example of this is organic celery. Now if an insect comes and starts chewing on it, ‘cause it’s not, it’s not sprayed the pesticides 13 since it’s organic.

Right.

It will produce its own chemical. And the chemical in it is really cool, it is called Soylent, and imagining it's my fist, when it exposes to the sunlight, my fist opens up, this is soylent, and it scratches all your insects. And an example of what can go wrong, a woman in Germany juiced a lot of celery and then went tanning, and suffered a second-degree burns.

Alright. And finally, now, we are going about 30 seconds left. This sounds like a stereotype 14, alright, that many Asians can’t tolerate alcohol.

So this turns out to be true. 50% of Asians lack a gene that allows them to break down alcohol efficiently 15. And what happens is that in an allergic 16 reaction, they appear drunk, their face gets red and flushed, but it’s great, ‘cause it actually protects them from becoming an alcoholic 17.

If you’re kind of a person who likes to look at medicine and medical mysteries and then kinda turn everything upside down, this is a great book for you. It’s called Survival of the Sickest. Sharon Molaem, thanks very much.

Thank you for appreciating it