The common hand shapes were arrived at via evolution, meaning they are the shape that most encouraged survival, and doing well enough for oneself to get opportunities to reproduce.

If the longest fingers were on the outside, they could get bent back or hyperextended if the short middle finger couldn't provide support. With the shorter ones on the outside, a person losing their grip would lose it one finger at a time. When the long middle finger loses grip on something, you're only holding on with one side of your hand so there should be more room to wriggle free.

Also, the traditional ratio of finger lengths allows a person to make a fist comfortably. So, the digits are typicallly the correct length to be curled up comfortably into a closed hand.

Fingers could be the same length. Women tend to have same sized ring and index fingers, meanwhile the ring finger tends to be longer than the index finger in male population (especially men exposed to higher concentrations of testosterone during fetal period.

Some studies suggest that larger fingers may give you an advantage in some sports, but it’s not fully understood whether fingersize really matters evolution wise.

Don’t hesitate to correct me if I am wrong.

[removed]

[removed]

[removed]

[removed]

[removed]

[removed]

Good question. My guess is that the difference is for a reason or reasons but I sure don’t have a clue what they’d be. It seems to me that nothing is just a fluke that’s represented in the vast majority of a species.