Cracking your knuckles makes them bigger/gives you arthritis.
"According to Harvard Health Publishing, “The ‘pop’ of a cracked knuckle is caused by bubbles bursting in the synovial fluid — the fluid that helps lubricate joints. The bubbles pop when you pull the bones apart, either by stretching the fingers or bending them backward, creating negative pressure.”"
Yes. That's because we don't need to. Any new action or sight will be remembered. But if you see it daily you won't.
But that's not the myth. The myth is that we only use 10% and if we somehow could use 100%, we'd all be a genius, get super powers, and whatnot.
We use all of our brain but parts are used more and others less depending on the particular action.
Probably because they play with a lot of friends in a time when the cold goes around. And if even one has it...
Correlation is not causation.