Space

I work/worked in science and I'd say it's humans. Especially old humans who get their egos tied up into their work.

Younger scientists seem to find it easier when they're told a concept that forms at least a portion of their previous work is wrong - many just roll with it. Time to do more research, hooray for enhanced job security.

Older scientists, though, tend to fight that change because even if the disproven concept is only 5% of their work, it's 5% of decades of work and their work has increasingly become part of their identity. That's a big part of the reason I stepped out of both research and lab work: so many snooty, old, white men who lack lives outside of their field of study. They're just exhausting to be around.