Of mice and men: the ethics of chimerism

Imagine you're at home, sitting in your favorite chair, when your child excitedly comes bounding into the room.

"Look what I got!" he shouts. He holds in his hand an ordinary cage, filled with sawdust and your typical, little white mouse.

"Great, you got your mouse," you say, knowing how badly he had wanted the pet.

"It's not a mouse," he says. "It's smarter."

"What do you mean?" you ask, taking another look at the furry white creature, which now suddenly does look a bit odd. Something about the way it moves its feet and looks at you ...

"It's a humouse," he replies with pride. "Its made with human stem cells."

"It ... what?"

Surprise or shock would seem to be fairly reasonable responses to the prospect of a mouse with human genes bioengineered into it. The very notion of forcing distinct sentient creatures to mix together into a new organism flies in the face of "ethical treatment," calling up visions of "The Island of Dr. Moreau" or worse.

But, despite the warnings and obvious immorality of the idea, there's a group of American and Canadian biologists who just can't wait for the opportunity to create this inevitably tragic new organism.

Last November, The New York Times reported on a proposed experiment involving the use of embryonic stem cells to create a "humouse," or a human-mouse hybrid. This process, which combines two different species to make a completely new one, is known as "chim-erism."

Since most animal testing is, ultimately, done for the sake of humanity, scientists are always looking for ways to make their experimental results more applicable to homo sapiens. Using animals in scientific research works sometimes, but far too often, animal physiology is different enough from a human's to cause significant errors to be present in the study. In an ideal situation, human subjects are used for more accurate findings.

However, there's a big catch: Tight restrictions are in place to limit which types of experiments can be performed on humans. All those messy ethical questions get in the way of effective results (or "should" get in the way, though this is not always the case. Just ask the Hanford downwinders or the "participants" in the Tuskegee experiments).

Barring a few exceptions, no such restrictions exist with animals. Stick a scalpel into a cat's brain? Sure, why not. Inject the AIDS virus into a monkey and watch it slowly die? Fine. But try this with humans, and you're not likely to get the same apathetic reaction.

And that's where the chimeras come in.

With chimerism, scientists would be able to perform tests on human cells and humanoid organisms without bending any rules or offending any of society's morals. Less spurious results can be obtained without having to sacrifice a single human life. It's the best of both worlds.

Well, that's the theory at least. In practice, however, we are likely to see exactly the opposite results.

At some point, either experiments are going to go awry, some scientist is going to overstep the ethical boundaries, or society's restrictions on creating "too-human" chimeras are going to lapse.

Whichever way it occurs, it will lead to the same result: Animals are going to become more human-like very soon. And they are likely going to start thinking and feeling in ways frighteningly similar to our own.

And when this happens, will we have the right to experiment on these new intelligent life forms? Won't this redefine our concept of "intelligence" and "human"?

Ultimately, it will lead many pro-experiment folks to ask the same questions that many animal-rights activists have been asking for decades: What exactly are we trying to achieve? And when will it be enough?

Sure, there's the typical, vague, "for the betterment of humanity" answer. Or possibly the more specific "until cancer is eradicated." But these responses don't get down to the marrow; they don't address the heart of the matter.

The answer to both questions can be found in one timeless objective: the quest for immortality.

We've eliminated the threat of numerous diseases, developed all types of beneficial medicines, dramatically increased life expectancy... yet still it's not enough. In the near future, people will live to be well over 100 years old. But then we're going to want to live to 200, then 300, 1,000 and so on.

Considering the population problems and dwindling resources the world is currently facing, we don't really need to live longer — we just need to live better. Of course, "better" is a tough word to define as a society.

But it's a sure bet that most people won't feel comfortable with the idea of experimenting on an animal with a "human" brain and "human" feelings. It's one step removed from Nazi science, and you'll be hard pressed to find someone eager to champion that cause.

The fact is, until we choose quality of life over quantity, moral and ethical issues such as chimerism will continue to plague us.

When it learns to speak, maybe a humouse can help us with the cure.

Joshua Ortega is a Seattle author and former journalist. E-mail him at jnaortega@omegapp.com. His Web address is www.joshuaortega.com.