It's hard to believe that we still don't understand the cracking-knuckles mechanism. The effect is so large!

Pardon the cruelty of my line of thought here... but do other animals exhibit the same effect? And could some intrusive measurements be done inserting probes into the affected areas, possibly damaging the flesh but revealing data? Even if there might be ethical concerns with such experiments today, I'm surprised that they were not carried out in decades past.

I suppose it's not the highest priority research...

The medical profession is like a bunch of garage mechanics that are working on the most complicated, convoluted, and fussy car ever with no manual. They are still reverse engineering our bodies. They are still discovering organs in the human body. (https://www.nytimes.com/2018/03/31/health/new-organ-intersti...)

>but do other animals exhibit the same effect?

I have an arthritic cat whose hind leg occasionally pops as loud as my knuckles. I don't know if it's the same phenomenon, but it sure sounds similar.

No, you can't probe her. :)

Snapping Shrimp have a claw designed to produce a cavitation bubble (in seawater, not within the joint itself), which collapses to generate one of the loudest sounds in the ocean.

https://en.wikipedia.org/wiki/Alpheidae

I'm pretty sure mantis shrimp (stomatopods) do the same thing. Apparently they're capable of smashing through the glass of aquariums if not properly reinforced.

TL;DR: it may (or may not) be due to the formation and/or contraction of a bubble of gas that forms in the joints: The verdict is still out.

I mean there has to be SOMETHING in there that is forming, and then being removed, right? I can't immediately crack my fingers again. There has to be a period of time, and it does appear the longer I wait, the larger the crack(within limits).

I agree that there must be something forming there. I can often 'feel' that a joint can be popped, prior to actually doing so, and sometimes, it seems, without even flexing the joint.

I can crack my fingers repeatedly by crossing my index/middle and ring/pinky fingers together respectively and closing my fist.

The jury is still out ;-)

"A Mathematical Model for the Sounds Produced by Knuckle Cracking" (original paper — basis for New York Times article) https://www.nature.com/articles/s41598-018-22664-4

You actually can't select text on the nytimes website? Instead they add a functionality where double clicking changes the font size. Looks like a bored designer is at work here...

I can select text just fine in that article (this is with Chrome on MacOS 10.12 running uBlock Origin)

Ah I'm using firefox; I suppose it's unintentional then.

Are you using a touchscreen computer? There's a bug on the NYT site with Touchscreen computers that disables highlighting text on Firefox. It's been bugging me forever, on my Surface Pro.

yes I have a touchscreen computer

I'm using firefox and the website functions normally.

this happens for me on my portrait mode monitor. I suspect some sort of mobile styling is at work.