If there is one thing science fiction has taught us, it is that nothing bad can possibly come from making monkeys more like human beings. The controversy surrounding a Chinese laboratory creating human-monkey hybrids with the help of a Spanish biologist based in California is therefore puzzling. What could go wrong?

Technology Review reported on Thursday, citing major Spanish newspaper El País, that biologist Juan Carlos Izpisua Belmonte, who presently works out of the Salk Institute in California, is working with Chinese scientists to create “human-animal chimeras” composed of human cells injected into monkey embryos. The term chimera comes from Greek mythology, which teaches us that nothing bad ever happens when mankind usurps the power of the gods.

The chimera concept is actually a hot ticket in biology at the moment. The idea is to infuse highly adaptable human stem cells into animal embryos, with the goal of producing an animal whose organs more closely resemble those of humans. Those organs would be useful in medical research, and might perhaps even be transplanted into humans, greatly alleviating the shortage of organ transplants.

Creating human-monkey hybrids is considerably less disturbing than some of China’s other ideas for increasing the organ supply, and it is not the strangest application of chimera technology to date. Early experiments in the field involved pigs and sheep. Japan is creating hybrids between humans and mice, which should have no problem finding work at anime studios or Disney World if their medical careers don’t pan out.

It took about ten years to lay both the scientific and legal groundwork for the Japanese project – initially banned by the government this year, but authorized after some ethical concerns were addressed and the medical potential of chimera technology was emphasized. Japanese researchers are convinced they will soon be able to use chimeras to create a human pancreas that could be used in organ transplants using larger animals like sheep.

“The number of human cells grown in the bodies of sheep is extremely small, like one in thousands or one in tens of thousands. At that level, an animal with a human face will never be born,” promised lead scientist Hiromitsu Nakauchi.

The monkey experiments in China are more ethically troubling, which is why they are happening in China, but also more promising because monkeys are genetically closer to humans than previous animal subjects. U.S. law explicitly prohibits federal funds from being used to create hybrid human-monkey embryos.

Even China’s more relaxed attitude on bioethics has its limits, as disgraced genetic engineer He Jiankui can attest. He appears to have dramatically overestimated the Chinese government’s willingness to let him establish a “genetic tourism” industry in which well-heeled customers from around the world would visit his clinic to have their unborn children upgraded with CRISPR gene-editing technology.

Technology Review summed up the scientific objections to the human-monkey hybrid project by quoting a scientist with experience in chimera technology, saying:

Pablo Ross, a veterinary researcher at the University of California, Davis, who previously worked with Salk on the pig-human chimeras, says he doesn’t think it makes sense to try to grow human organs in monkeys. “I always made the case that it doesn’t make sense to use a primate for that. Typically they are very small, and they take too long to develop,” he says. Ross suspects the researchers have more basic scientific questions in mind. Injecting human cells into monkey embryos could address “questions of evolutionary distance and interspecies barriers,” he says.

Another Spanish research working on the project, Estrella Nunez of Murcia Catholic University, described the early results as “very promising.” However, the hybrid embryos have not yet been allowed to live for more than a few weeks.

Keeping chimeras alive is difficult because the human and animal cells go to war against each other, with the human cells faring poorly. Researchers are fascinated by the phenomenon of cellular competition and believe it might eventually be controlled to produce transplantable organs of superior quality to the “xenotransplantation” method, which involves tweaking the cellular structure of animal tissue to make it more compatible with human recipients.

The obvious fear that chimera research could produce an intelligent animal or something from The Island of Dr. Moreau is taken seriously by scientists in the field. The Japanese government pondered concerns that a chimera might become intelligent enough to acquire human rights, even if it falls far short of developing human thought patterns or the ability to speak. The need for a generous supply of transplantable organs, and the other medical possibilities of chimera research, are currently balanced very delicately on the scales against the ethical concerns and possible legal complications.