Mixing species--and crossing a line?
The upcoming workshops on chimeric brains will bring together experts on primatology, neurology, ethics, and stem cells to assess whether such experiments might create monkeys capable of humanlike thought or experiences. If so, the panels will need to ponder whether scientists can ethically create such beings, and how researchers might recognize that their monkeys had become something more than lab animals.
It's familiar ground for Stanford University bioethicist Henry Greely. A few years ago, his Stanford colleague Irving Weissman, a stem-cell researcher, began thinking about experiments in fetal mice that would replace part or all of their brains with human neural stem cells. A living mouse with a brain made entirely of human neurons could be a boon for scientists trying to test drugs aimed at the nervous system, but Weissman knew his proposal would generate controversy. So he consulted with Greely, who put together a team of experts to consider it.
"We ultimately concluded that it should be taken slowly and carefully," says Greely. For example, scientists could monitor the brains to ensure they retained normal mouse structures, like a smooth surface. Any change that made the mouse brain look more like the wrinkly human organ would require a pause and reconsideration. But Greely thinks real problems seem unlikely, as mice have tiny brains.
Primates, he says, are a different story. "Nobody expects a mouse to stand up on its hind legs and say, `Hi, I'm Mickey,' " Greely says. "If you proposed doing this experiment on fetal chimps, I would be a lot more leery."
advertisement
