Redesigning Humans: Our Inevitable Genetic Future

  • Gregory Stock
Houghton Mifflin: 2002. 288 pp. $24
Credit: DAVID NEWTON

William Thomson (later Lord Kelvin) entered Glasgow University at the age of ten, achieved a first in mathematics at Cambridge, published over 600 scientific papers, and became president of the Royal Society in 1890. He was a pioneering physicist but, like many competent scientists, he was not a brilliant futurologist. Less than ten years before the Wright brothers flew he said: “I can state flatly that heavier-than-air flying machines are impossible.” And he once claimed: “X-rays will prove to be a hoax.” Given his views on creationism — “overwhelming strong proofs of intelligent and benevolent design lie around us” — one wonders what he might of made of the implications of modern molecular biology.

Our imperfect knowledge of DNA and the human genome raises more unanswered questions than any other aspect of science. People from all walks of life are nervous about the implications of genetic knowledge and genetic manipulation. The heat of debates on reproductive cloning and genetic testing is evidence of the anxieties of so many people. This carries a salutary lesson. If scientists misrepresent or exaggerate the power of these technologies, or are not scrupulously objective, the pursuit of knowledge is threatened. Unlike those relatively uncritical golden days of Lord Kelvin, our pronouncements will have a profound effect on public perception and the health of science, and thus on society.

One oddity about the debate on the interface between genetics and human embryology is that it has often been wrongly focused. Given the risks of producing an abnormal child — and the litigation that would ensue — I cannot believe, for example, that human cloning will be attempted in any significant way. So the crucial issue is the use of transgenic technology. We can make transgenic animals with relative ease; and we can add, modify or knock out genes in intact mammals. The key question is whether these technologies might be used in humans.

Gregory Stock of the UCLA School of Medicine bravely predicts this future for humanity. He is undeterred by the poor record of futurology, believing that it is only a matter of time before human germline modification becomes a fact. His new book, Redesigning Humans: Our Inevitable Genetic Future, is a distillate of opinions he has publicly expressed for some years. He writes with a clear, lucid style that lends plausibility to his views. Yet many readers will wonder whether the assertions about reproductive technology that are crucial to his argument are accurate. For example, he makes claims for the profound global impact of contraceptive technology. Without the worldwide access to birth control, Stock asserts, birth rates would not be falling. But this does not stand up to scrutiny. Falling birth rates are more to do with improved social infrastructure — better hygiene, education, decreasing infant mortality and changing social attitudes — than with his technocentric approach.

People will want genetic choice, claims Stock. He seems to believe that human nature will change so much that assisted reproduction could replace procreation on the hearth-rug. We have, he says, now accepted much of what is ethically debatable in the area of genetic choice, by using preimplantation genetic diagnosis (PGD) in embryos. PGD will be “in the vanguard of genetic choice, at least for the next couple of decades,” Stock contends. But this is not likely to be even approximately true. Only one-fifth of embryos resulting from in vitro fertilization are viable; many, if not most, human embryos are frequently aneuploid or have other cellular abnormalities that are probably incompatible with development. Mosaicism is extremely common — perhaps 75% of morphologically normal human embryos have at least one or two aneuploid cells at around the eight-cell stage. Biopsy of such cells will be likely to give useless clinical results, and PGD biopsy of a normal cell in such an embryo may lead to false diagnosis.

So if Redesigning Humans is wide of the mark when discussing technology that has already been used for over a decade, why should futuristic comments about germline modification be any closer to the truth? Stock rightly observes that current transgenic manipulation is unpredictable, but he seems overimpressed by recent developments. It will be relatively easy to introduce auxiliary chromosomes into the germ line, and they could carry large chunks of DNA without the limitations mostly imposed by conventional gene vectors. Genes on these chromosomes could be introduced without changing other parts of the genome and could incorporate a mechanism for terminating expression to improve safety.

Stock argues that this strategy could eventually be used to enhance “desirable” characteristics for single generations and that outdated auxiliary chromosomes could be jettisoned for newer, more up-to-date models. Work in mice, he feels, suggests that this could eventually be done without human harm. But many geneticists will feel queasy; the potential for gene imbalance is huge and the change in phenotype unpredictable.

This is an important debate, but a real moral perspective is missing in this mostly engaging book. Stock favours human genetic enhancement. He quotes James Watson: “If we can make better humans... why shouldn't we?” And he is scathing about the conservative attitude of notable scientists such as French Anderson. To many readers elsewhere, his view will seem centred on privileged North America, taking little cognisance of the appalling inequalities in his and their society which would be increased by this manipulation. We are as much the product of our environment as of our genes, and much should be done first about the poor environment in which so many humans exist. For scientists to advocate channelling resources uncritically, as this book seems to do, is to risk bringing genetic research into public disrepute.

Whatever the true mechanism, perhaps Lord Kelvin was not so misguided after all in his faith in the goodness of “benevolent design”. As a Christian he might have asked: if we change the very nature of what it is to be a human, will we still have our humanity?