Who are smarter, rocket scientists or brain surgeons?

We use 'it's not rocket science' and 'it's not brain surgery' almost interchangeably to say that we don't think something is very difficult to do or to understand. Which phrase is more deserving? And more importantly, should rocket scientists or brain surgeons be crowned the winners of the wits?

source https://medicalxpress.com/news/2021-12-smarter-rocket-scientists-brain-surgeons.html