I heard an NPR interview yesterday, and they were pretty clear that they based this on previous studies done by others that found it in rats. They had to spend

I heard an NPR interview yesterday, and they were pretty clear that they based this on previous studies done by others that found it in rats. They had to spend 2-3 years figuring out the right technique to test for it in human cadavers, so their work was really in confirming that the same system is present in humans.