Is It Dangerous

There is a whole range of possible objections that have nothing to do with the health or life conditions of what we could probably call chickenosaurus. And that is fear for the environment, for interfering with the delicate ecological balance of the planet. Many people fear genetically modified crops, for instance, or genetically modified foods. It seems to me that the odds of harm occurring from eating genetically modified foods are very small. There is, of course, always a small chance that something new will cause an allergic reaction in some people. Other than that, the nutritional value of the corn or meat seems the same. Genetic modification also occurs in traditional selective breeding, or the kind of grafting and hybridization that goes on in developing new plant and seed varieties.

Selective breeding does not, of course, move genes from one species to another, and again there is some possibility for surprise. But I am getting away from chickenosaurus. If the embryo is not allowed to hatch, then it won't be out in the environment at all. If it were allowed to hatch, and somehow escaped, the only problem would be the chickenosaur figuring out how to survive. It would not be a danger to the environment or to the billions of chickens in the world, because, as I've described, we would not be changing its genetic makeup. By manipulating growth signaling factors we would be switching genes on and off at different times during development, but not changing the genes themselves. Genetically, chickenosaurus would still be a domestic chicken. And if it were somehow to breed with a chicken, the result would only be more chickens.

Think of the difference in height between some immigrant groups and their children. Better nutrition during pregnancy and childhood leads to an increase in height. But there has been no genetic change. The growing child has simply had more fuel and, with the same genes as shorter parents, has grown taller.

A less happy but similarly instructive example could be babies born addicted to heroin or cocaine because of a mother's habits. When the baby grows up there are no new addiction genes that it can pass on. So chickenosaurus would be harmless.

If our understanding of embryology and evolution reaches the point at which we know how to alter DNA to change the growth program, then we could make animals that would pass on their characteristics to their offspring. That will bring up another set of potential problems. It seems unlikely that chick-enosaurs would take over an environment rife with raccoons, opossums, cats, dogs, coyotes, foxes, fishes, snakes, rats, and people. Still, altering the genes of an animal, as is done with knockout mice, is not something I am suggesting.

That would really produce the possibility of Jurassic Park, and attendant problems, although probably not vicious raptors rampaging through the kitchens of Southern California. More important would be the question of whether such animals would be functional in the outside world if they escaped. Even as an invasive species, they could disturb environmental equilibrium.

Bringing back an extinct animal, or a reasonable facsimile of an extinct animal, is one thing. Actually bringing back the full species, or one like it, capable of reproducing and spreading in the wild, would be something else altogether. George Carlin, the brilliant comedian and social commentator who died recently, had a great routine in which he talked about endangered species and extinction. His point, made much better than I can, was that saving endangered species was just one more example of human arrogance, of interfering with nature. He noted that well over 90 percent of all species that have ever existed are gone. "They disappeared," he said. "Let them go."

Finally, there is the question of where this research will take us. Having learned to redirect embryonic growth in chickens, we might well extend these abilities. Chickens are, of course, so much easier than mammals to work on because the embryos are large and encased in convenient containers. They can be kept incubated and growing on their own while we add beads or inject retinoic acid.

But such techniques can be refined, and the more they are successfully used the more we will want to use them. We could use what we learn to alleviate human suffering in children now born with neural tube defects. We might be able at some time to intervene during the growth of an embryo, to override problems and ensure that growth continues as planned.

On the other hand, there is public disagreement about what a defect is. Different lines of research have supported an idea that sexual orientation has a genetic determinant or is affected by maternal hormones during pregnancy, or both. These are hypotheses that have some evidence, not well supported theories. But if, in fact, sexual orientation in some mammals is shown to be largely or partly the result of the presence of a hormone during pregnancy, some parents might be tempted to test hormone levels during pregnancy and adjust them to influence the sexual orientation of their child.

Other interventions could be tempting, too, perhaps for improved intelligence or athletic ability. This would not be genetic engineering. Ethically, someone might argue that it is no different than giving folic acid or intervening in some other way to prevent neural tube defects. But there is general societal agreement about the desire for babies that are healthy and not in pain, while there is bitter disagreement about other interventions. Would we want a world where some mothers receive treatment during pregnancy to increase the intelligence of their children, or to prevent them from being gay, or to cause them to be gay?

These may seem farfetched, but genetic testing of embryos is now in use with in vitro fertilization, mostly to screen embryos for known genetic diseases with devastating effects like Tay-Sachs, which can cause profound mental and physical disabilities. And it has been used by some parents who are dwarfs to ensure that their children will also be dwarfs, or by some parents who are deaf to ensure that their children are also deaf. There is no law against genetic screening of embryos for other traits, and it would be hard to imagine a law against a woman adjusting hormone levels during a pregnancy.

I can say what interventions I would find reasonable, but I am not the one to decide. That is for society at large. What I and other scientists can decide is whether or not to pursue knowledge that has the potential to teach us a great deal and to provide powerful tools that could be used for good purposes and bad. I am a hard-liner when it comes to knowledge. My work is all about finding things out, about learning, and I operate on the principle that we should try to find out as much as we can about the way the world works. I don't stop and say, Could this research find out something that might be misused, might cause more evil than good? I follow my nose to see what is interesting. When it comes to the question of how that knowledge is used, I am just another citizen.

Other hands will be trying to grow a dinosaur. But it's a project that I intend to support and campaign for in any way I can. If this book provokes a discussion, disagreement, and serious consideration about the project, great. If it helps get the research going, even better.

There is an image that keeps popping into my mind. I give an awful lot of lectures. I don't read from notes, I prefer to use slides, each of which fits with a topic that I want to talk about. I don't need to memorize a speech, or make it formal, I can stay conversational, which is what I find most comfortable.

So the image I have is that I walk onstage with a dinosaur on a leash. It's small, but bigger than a chicken. Let's say it's the size of turkey, one day maybe even the size of an emu. The dinosaur, or chickenosaur, or dinochicken, the emu-sized ver sion of a dinosaur (that one might have a muzzle or a couple of handlers) is the ultimate slide. Instead of a lecture, this would be a public science class with questions and challenges about how it was done, what its skin feels like, does it have teeth, what does it eat, how close is it really to a dinosaur? What would inevitably follow would be a discussion about the nature of dinosaurs, of birds, of evolution and development, of the relationship of molecular biology to big changes in evolution, of how we know what we know, and whether we were justified in doing what we did. It would be something like this book, in conversational form.

That would be the most satisfying lecture I could possible give. I don't like providing answers. I never have. I like questions. I like asking them, trying to figure out answers, trying to figure out what we are really asking, and what new questions come up. For this event I won't have to prepare any speech at all. My entire prepared text will consist of one simple question, from which everything else will follow.

I'll walk to the edge of the stage, point to the creature on the leash, look at the audience, and say, "Can anyone here tell me what this is?"



Cours Collectife Questre Dessin

A quick look at the skeletons on these two pages would suggest that they are similar animals. No scientific expertise is necessary to see the two legs, the long neck and tail, the rib cage of each animal. Well, they are the same sort of animal; they are both dinosaurs. At left is Saurornitholestes, a small, theropod from the Cretaceous of North America. At right is Chickenosaurus, a small, so-far imaginary dinosaur from the future.

Birds, as I have been saying throughout the book, are dinosaurs, and these two drawings make it clearer than any words. Saurornitholestes is drawn as it was, or as best we know it, from fossils. Chickenosaurus is a rough sketch of the creature I am certain we can grow in the near future from a chicken egg. It was drawn by adding a tail and dinosaurlike arms to the skeleton of a chicken.

Chickenosaurus Skeleton

The arms on Chickenosaurus are clearly different from chicken wings and would require getting the forelimbs of an embryo to grow in a very different fashion. And there is the tail, which would be achieved by interfering with the instructions that stop backbone growth.

These changes would not make Chickenosaurus the same as Saurornitholestes, of course. There are differences in hip and chest structure, and in the skull, among others. But the skeletons show clearly the similarities and the small distance between the two creatures, which can be obscured by the familiar appearance of a living chicken and the way we think of dinosaurs.

Was this article helpful?

+2 0

Post a comment