why do humans shake asses when dancing?

A long time ago, the people had tails like cows...
Through circling movements of the tails, they tried to hold the balance...🤔

Today, that remained so... only most people don't have tails any more ...or if.. their tails are only very small..🔎

Cuz if theyre movin its a shaken. It doesnt matter if they try or not.Im

That’s all we got to shake.

why dance at all?

If I had one I'd shake it too

If I shake my eyeballs I get dizzy

Only a very small subset of humans do that and an even smaller subset is any good at it.