Here’s something that will make your head spin: A Chinese doctor has been surgically transplanting the heads of mice—and he eventually wants to perform head transplants on humans, too.

Surgeon Xiaoping Ren has performed roughly 1,000 head transplants on mice since 2013, and has had more success than anyone else with the surgery, according to a report in the Wall Street Journal. The mice—whose new heads sometimes have different colored fur than their bodies—have lived as long as a day after the operations.

Next, Ren plans to try his technique on monkeys, “hoping to create the first head-transplanted primate that can live and breathe on its own, at least for a little while,” the Journal says.

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