Trespassing into the field of Genetics

Bill Meredith

The February 17 issue of Time magazine lies on my desk as I write. It celebrates the 50th anniversary of the solving of the structure of DNA, by James Watson and Francis Crick, in February, 1953. Today, every school child knows DNA is what genes are made of. But just a couple of years before then, most biologists had believed genes were made of protein; it was only in 1950 that compelling evidence was found that they were made of DNA. Hence Watson and Crick?s discovery of how DNA was put together revolutionized the entire science of genetics. It ranks as the most important biological discovery of the 20th century; in fact, only Einstein?s theory of Relativity rivals it as the most important event in all of science over that time span.

Although I was in college in 1953, I was not aware of Watson and Crick?s work. I took a course in Genetics the following year, and learned nothing about them then either. There was nothing about DNA in the textbook; I remember the professor mentioning that someone had ?discovered the gene,? but no details were given. I thought I knew a lot about heredity when the course was over, but I was woefully mistaken; I really knew very little, and some of that was wrong. For example, studies done in the early 1920?s had found the number of chromosomes in human cells to be 48; this had been quoted in every biology textbook since then, and had been memorized by thousands of students, among whom I was one. Two years later, in 1956, Joe Hin Tjio (who died just last summer, at the age of 86) found that the correct number of human chromosomes was 46. I was in graduate school by that time, and it came as a shock; it was the first time I had the experience of finding that something I had taken to be a scientific fact was wrong. To my surprise, the entire edifice of genetic knowledge did not collapse; everybody simply learned the new number and went ahead, confident that our knowledge was now a little more accurate. The lesson I took from it was that all scientific knowledge is incomplete, and the scientific method is self-correcting. I was a lot less dogmatic about things after that.

More by luck than by foresight, I started teaching genetics in 1960. (This is not as peculiar as it may sound at first; there actually is a field called ecological genetics!) The first course I taught was not much different than the one I had taken in college; by that time, DNA had worked its way into the textbook, but only a week or so was devoted to it. By the time I retired, everything I had learned in my own college course was covered in the first three weeks of the semester; most of the rest of the course dealt with DNA. I still have my college genetics textbook; I kept it as a reminder of how much the field has changed. It cost $4.50, and had a little over 300 pages; DNA is not even listed in the index. The book I used the last time I taught the course (1998) now sells for $114, and has over 800 pages.

By the time I retired, the field of genetics was growing so fast that the sum total of the world?s knowledge about it was doubling every three years. This growth is not just a matter of academic interest; it touches the lives of everyone. It has been involved, directly or indirectly, in most of the enormous advances in medicine that have occurred in the past 50 years; it dominates the pharmaceutical industry. Likewise, it has revolutionized agriculture and animal husbandry; it has a major impact on our national economy through the production of crops and food animals. It influences foreign policy; recall the controversy about sending genetically engineered corn to Africa in the effort to combat famine. And possibly within my lifetime, certainly within the lifetime of my children, it will force the civilized world to confront the most intractable moral dilemma it ever has had to deal with. That dilemma arises from the collision between the results of applying genetic knowledge to the human condition and the inexorable laws of ecology.

The basic effect of applying genetic knowledge is to increase the human life span. This has traditionally been done in a number of ways, principally by improving nutrition and medical treatment of diseases; but the prospect is now in sight that we may be able to slow or even stop the aging process. This would be wonderful for us individually; but it would be disastrous for us as a world population.

It appears that the maximum potential life span for humans is about 120 years. The average life expectancy now is about 78 years in Western Europe, and about 76 in the U. S.; it is increasing in both areas. It is much lower in Third World countries, but is increasing there also. Meanwhile, the world?s population presently has surpassed six billion; the most conservative estimates indicate the population growth rate will begin to slow down around 2030, and may be a bit over 9 billion by 2050 (less conservative estimates indicate 13 billion by then). Even if, by some miracle or fiat, we could limit every family to two children as of today, the population would not stop growing for one human life span, that is to say, seventy-odd years. Thus slowing or stopping the aging process would indefinitely prolong population growth, at a time when we already have more people than the earth can feed. Hence the dilemma: shall we not try to stop aging? ?or shall we do it for everyone? ?or limit it to some privileged few?

Most predictions fail because they are founded on the basic assumption that fundamental processes will remain constant in the future. This is especially true of computer models such as those about population growth. 25 years ago no population expert would have predicted that AIDS might kill half the population of Africa; today, the infection rate exceeds 50% in many places. Ten years ago, few people considered the possibility of major wars based on religion, or the threat of biological and chemical warfare; today, many see the conflict in Iraq as the beginning of that. Ecologists have warned for years that increased population density and mobility would result in increased vulnerability to disease; today?s news told of an outbreak of Ebola virus in Africa, an impending epidemic of avian influenza in China, and increased resistance of a number of diseases to antibiotics in the U. S. And so it goes. Somewhere, the Rev. Mr. Malthus nods his head knowingly.

It is said that the Greek philosopher, Diogenes, spent his later years wandering about with a lantern, looking for an honest man. I sometimes think I may have to take a similar tack, looking for an optimistic ecologist. There may yet be time; but lately, I haven?t seen one.