Lee Silver on cloning, biotechnology

May 21, 2001 6:14 p.m.

Lee Silver, professor of molecular biology and public affairs, is an authority on the subject of behavioral genetics. He also has become a leader in addressing the societal impacts of biotechnology, particularly in the area of reproductive medicine.

In 1997, shortly after Scottish scientists announced the cloning of Dolly the sheep, Silver published his book "Remaking Eden: Cloning and Beyond in the Brave New World," which has since been translated into 14 languages.

As he notes in the text of his University Web site, "Prospective parents will soon be able to choose which of their genes to give to their children, and whether to add in genes they don't even carry, in order to provide them with increased chances for health, longevity, happiness and success."

In recent weeks, questions related to cloning have returned to public discussion. Congress held hearings in March on potential anti-cloning legislation. Recent reports have shown that cloned animals suffer a number of birth defects, some of which do not manifest themselves until later in life.

In light of these developments, the Princeton Weekly Bulletin asked Silver to answer some questions about cloning and biotechnology. Here is an excerpt:

Question: In the four years since Dolly and "Remaking Eden," what have been some of the most tantalizing or discouraging scientific developments related to reprogenetics?

Answer: The most tantalizing development has been the decipherment of the human genome, both ahead of schedule and under-cost. We now have a nearly-complete catalog of the 30,000 or so genes present in every human cell.

This catalog provides an incredibly powerful tool for working out the genetic influences on all the diseases that people get. In turn, this information will lead to the development of new therapies and drugs that will continue to extend both lifespan and quality of life.

Biotechnology has become more powerful and sophisticated (much more quickly than I expected) with the integration of tools from the computational sciences and engineering. The genomes of many other organisms of value to humankind are also under analysis to develop new products and therapies.

The most discouraging development is not a scientific one, but a social one. Unfortunately, as the promise of biotechnology has grown ever greater, many people around the world have become more and more fearful of the technology, in large part because they don't understand it.

Of course, all new biotech protocols must be properly vetted in terms of safety to human health and the environment. But the wholesale rejection of biotechnology is shortsighted and self-defeating.

Question: What are the biggest hurdles in the way of human cloning and human genetic engineering? How long will it be - five years or 50 - before they are cleared away?

Answer: My feeling is (and always has been) that cloning is highly over-rated.

If people understood what the actual technology could accomplish - and more importantly, what it couldn't accomplish - most of the hysteria associated with the various notions of a "clone" would die away.

Recent data from animal experiments indicate a high rate of birth defects associated with the process, and a continued low rate of efficiency.

Thus, for these reasons alone, I believe it is unethical for clinics to offer this procedure to their clients at the present time. With enough time and effort, I suspect that the technical problems could be overcome (although I could certainly be wrong about this). Nevertheless, there are some clinics that are going ahead anyway, and thus, I expect that we will see "monoparental children" born in the next decade.

Question: What diseases would be the simplest, most obvious candidates for genetic engineering? Assuming such early attempts go well, what further "enhancements" are likely to come next?

Answer: There are many small changes that could be imagined right now, like providing resistance to infection by HIV (the virus that causes AIDS), or decreased susceptibility to some forms of cancer, obesity, heart disease and Alzheimer's disease (to name a few such diseases).

However, I don't think that genetic engineering of embryos will be practiced until a certain threshold is reached where the advantages provided by the technology are large enough (and safe enough) to overcome the disadvantages of using a radical new technology in the process of reproduction. The threshold could be crossed when genetic engineering provides safe and strong protection against all of the common diseases that people get as they age, as well as a generalized increase in lifespan.

In the beginning, I think that all "enhancements" of embryos would be based on people giving their own children the genes that some lucky other children get naturally.

Question: When you consider the future of your own children growing up in an age of reprogenetics, what is your biggest source of worry and optimism?

Answer: The optimism is that my daughter will be able to have children who do not suffer from asthma like she and her father do, and that my grandchildren will be protected from the ravages of many other diseases. The fear is that existing disparities between rich and poor will be exacerbated and genetically ingrained.

However, my colleagues in the economics department assure me that my fears are unfounded, and that free markets and free trade will bring people together rather than pull them apart.

Contact: Marilyn Marks (609) 258-3601