Changing Monkeys’ Behavior and Intelligence Raises Major Ethical Issues

Scientists in China have created a new kind of monkey. It’s got a human brain gene. And that just might make its intelligence a little bit more like ours. That, in turn, makes its fate — and its very existence — very ethically fraught.

In a study published last month in Beijing’s National Science Review journal, researchers took human copies of the MCPH1 gene, which is believed to play an important role in our brain development, and introduced it into monkey embryos by means of a virus that carried the gene.

Of the 11 transgenic macaque monkeys they generated, six died. The five survivors went through a series of tests, including MRI brain scans and memory tests. It turned out they didn’t have bigger brains than a control group of macaques, but they did perform better on short-term memory tasks. Their brains also developed over a longer period of time, which is typical of human brains.

Although the sample size was very small, the scientists excitedly described the study as “the first attempt to experimentally interrogate the genetic basis of human brain origin using a transgenic monkey model.” In other words, part of the point of the study was to help tackle a question about evolution: How did we humans develop our unique brand of intelligence, which has allowed us to innovate in ways other primates can’t?

The Chinese researchers suspect the MCPH1 gene is part of the answer. But they’re not stopping there.

If you make primates smarter and more human-like, you’re not doing them any favors — not least if you’re going to then keep them locked up in a lab. In the words of University of Colorado bioethicist Jacqueline Glover, “To humanize them is to cause harm. Where would they live and what would they do? Do not create a being that can’t have a meaningful life in any context.”

In a 2010 paper titled “The ethics of using transgenic non-human primates to study what makes us human,” Glover and her co-authors wrote that it’s unethical to add human brain genes to apes (such as chimpanzees). Su told MIT Tech Review he agrees that’s out of bounds given how similar apes are to humans — after all, chimps and humans share a recent common ancestor and 98 percent of DNA.

But monkeys aren’t apes. The last time they shared an ancestor with us was 25 million years ago, which Su thinks changes the ethical calculus. “Although their genome is close to ours, there are also tens of millions of differences,” he said, adding that for monkeys to become meaningfully un-monkey-like would be “impossible by introducing only a few human genes.”