TOPICS > Science

Genome: An Autobiography

February 29, 2000 at 12:00 AM EDT


RAY SUAREZ: We’re unraveling one of the biggest scientific discoveries concerning one of the smallest bits of information, the human genetic code. A new book, Genome: The Autobiography of a Species in 23 Chapters, explains how mapping out our human DNA could change everything from medicine and politics to what it means to be human. The author of the book, Matt Ridley, is a former editor of the Economist Magazine, and joins us now.

It helps the non-scientists really understand these articles that have been bubbling up on the news pages lately. There’s a nice passage close to the beginning of the book that starts, “Imagine the genome is a book.” Take it from there.

MATT RIDLEY: Well, I think, in a funny way, the genome is a book. I mean, that’s one of the great discoveries, is that there is an instruction manual– a recipe, if you like– written inside ourselves. It’s 800 times as long as the Bible, but it’s very small, because we’ve got 100 trillion copies of it. And it’s broken up into 23 chapters– 23 individual pairs of chromosomes, we call them. And so that’s what I did with my book, was split it into 23 chapters and try to tell one story from each chromosome. The stories are the genes, if you like. There’s 80,000 of them on these various chapters.

RAY SUAREZ: Well, a lot of scientists have said over the years that when faced with the option of complexity or simplicity, that nature has a bias toward making things more simple. So why do we have this thing that’s billions of letters long, replicated hundreds of millions of times in every one of us?

MATT RIDLEY: Well, it’s simple in concept. That’s what’s so nice about it. I mean, it actually uses a very simple code. It uses an alphabet that’s simpler than the one you and I use. It’s got four letters in the alphabet, and each word is three letters long. But if you think about it, if you had to write down the recipe for how to build and run a human body, it would be quite a big instruction manual. And that’s why it has to be so complex. And unraveling it, reading it for the first time, which is what’s happening now– it seems to me it’s very appropriate it’s happening in the first year of the millennium– will set out a cornucopia of knowledge for us to explore for many decades to come.

RAY SUAREZ: In these latest decodings of parts of the genome, they’re finding a lot of repeats– long, long, long repeats– of thousands of these sequences that don’t apparently have any purpose. Why would we do that?

MATT RIDLEY: Well, that’s one of the really fascinating discoveries, I think, about our genomes, and in a sense, it’s rather a disturbing one. The actual messages that count are only a small proportion of the text. A lot of the rest, some 24%, consists of two sequences that are repeated over and over and over again– just 100 or 1,000 letters long– and just repeated again and again and again. And the reason they’re there, we now think, is because they’re good at being there. They’re almost like computer viruses that have got into the system and copied themselves all over our hard disk, as it were. We’ve got them under control. You know, our bodies function without them running away with us, but they’re the evidence of sort of parasitism of our genes.

RAY SUAREZ: The book is full of warnings. At the same time as you’re talking about how determinant these genes can be, you sometimes feel like you’ve got to pull on the reins and say “whoa,” and tell us all the things the genes are not doing, at the same time as you’re telling us what they are doing. That must have been tough.

MATT RIDLEY: Well, it is tough, because you tend to get carried away I think these days with genes, and how they are controlling everything in our bodies. And sure, they’re involved in lots of things, but the interactions between genes and between genes and the environment means that it’s a very complex story, and you know, the simple idea that one gene is going to sort of be pulling a string and making us into a certain kind of personality or something like that is too simple, and it’s not going to be that simple at all.

RAY SUAREZ: Well, how about the example of the search for, in the popular mind, genes that are connected to a specific disease, is it really the gene connected to a specific disease?

MATT RIDLEY: Well, yes. I mean, the problem is… I mean, sometimes the only thing we know about a gene is that it’s connected to a specific disease, that when the gene goes wrong, you get a disease like Huntington’s Chorea or something from the gene going wrong. But that’s a bit like saying the only thing you know about heart is that you get a heart attack when it’s not working. There are obviously more interesting things you can say about hearts than that, and it’s much more interesting trying to understand what the gene is really doing when it’s functioning right, as well as what happens when it goes wrong. Genes are not there to cause diseases. Diseases are sometimes caused by faulty genes. And a lot of things like cancer, heart disease, Alzheimer’s Disease, very common diseases, have a strong genetic basis. I mean, there are genes involved in producing that disease, and understanding them is going to shed new lights on therapy.

RAY SUAREZ: Here we are looking forward to years where we’ll be understanding this code, billions of letters long, more and more, and yet it’s unlocking the past for us in a kind of way, the way human beings moved around the earth, and even how much in common we have with chimpanzees. Do you feel different about your own humanity, now that you’ve finished understanding this?

MATT RIDLEY: Yes, I think I do. I mean, certainly the lesson of the genome does drive home our kinship with other species. I mean, at the genetic level, we’re 98% chimpanzees, and that’s quite close. But also, more than that, I mean, if you’re going to look at fruit flies, you find there’s a lot of similarities in genes there. Genes that fruit flies use to plan the development of their bodies are genes that we use, as well. And that implies that the common ancestor of humans and fruit flies, which lived 600 million years ago, must have had these genes, too. And so, you know, just by… That’s why I call it an autobiography of our species, because in a sense you can look back and read about our past as an animal, and indeed the past of our ancestors, too.

RAY SUAREZ: There’s a lot of misgiving at the same time, a lot of unease that people feel about unlocking these mysteries, and our responsible use of what they tell us, isn’t there?

MATT RIDLEY: Well, it is a… I mean, knowing this knowledge has huge opportunities, obviously, for curing cancer and things like that. But it also brings great risks: Risks that we might misapply this knowledge, that we might do things with it that could be unethical and cruel. And we have to watch that very carefully. We have to tread very carefully into the future. I mean, if we were to start genetically engineering our children, not just to get rid of cruel diseases, but also perhaps to enhance their intelligence or their musical ability or something like that, then that would be a very dangerous step. And that’s something that we have to tread very carefully, while we work out how society deals with problems like that.

RAY SUAREZ: Well, in your book, you mention things like Downs, even gender– some of the birth defects that children can be born with, and how they may be connected with genes. Are we at risk of turning all the kinds of variations of human randomness, our wonderful diversity, into something to be cured once we know what gene connection there is?

MATT RIDLEY: I don’t think we are at that risk, and the reason I think that is because there doesn’t seem to be one consensus on what makes a desirable child. And in fact, if you look at the use of in-vitro fertilization, it hasn’t led to people selecting only one kind of child to have. It’s actually increased the desire for diversity, for everybody to have their own children, and so on. And I think that will continue to be the case. Not everyone’s going to have the same criteria about what a desirable child should be. There is obviously… There’s a difficult line to draw between what is curing a problem, and enhancing or standardizing what is really quite a normal condition. And that’s… How we draw that line is the big policy issue that faces us, I think, in the next few years.

RAY SUAREZ: And a line that may be moving from year to year to year?

MATT RIDLEY: Well, that’s right. I think people’s ideas about what is acceptable do change once they come up against reality. I mean, you know, in the abstract, people say, “well, I wouldn’t want to be able to do that.” But if you’re sat down in the privacy of a doctor’s office, “would you like to fiddle with the genes of your child or not?” I think perhaps the best defense is to swamp up with too much knowledge. I mean, at the moment, we know a few hundred genes, and the temptation is to think they’re very important. But once we know all 80,000, and we say, “would you like to change half of these,” it begins to seem much too daunting a task, and you begin to realize just how complex it is, and how if you pull one little thing out of the puzzle, the whole thing might change.

RAY SUAREZ: Matt Ridley, thanks for being with us.

MATT RIDLEY: Thank you, Ray.