Why Do Humans Have Butts?

Alternatively, we have Radiolabs 'Homos Erectus' story of why do humans have butts? 

https://www.wnycstudios.org/podcasts/radiolab/articles/man-against-horse

First they noticed the pigs do have the thing humans and all running animals have to hold their head in place when running. This think attaches to back of skull and they found first evidence of is existence  in museum on 2 million year old, homo erectus skull fossils. And they found evidence of other new things that non running animals dont have. Ex arched feet bones, ear canals for better balance, shorter arms, shorter toes and the butt muscle that keeps humans from falling flat on their face when running. Long story short, for first time, human { Nick Coury } beat horses in 50 mild race in AZ { prescott? }.

What caused this change to homo erectus?  Was random fluke of natural selection?  Was it aliens from space?  Was it RNA and/or DNA from space metorite or comet passing by?

i have an ass in order for all ya'll to kiss it... :-D

Down the rabbit hole we go (enema first though).

Man kicks horses ass in 50 mile race and their top race horse must kss mans ass for first time of this 20 plus year event.

Down the rabbit hole may leads to higher protein diet, bigger brains, foot arches,  shorter toes, and larger butts all so humans can run, their

high-protein-prey, to exhaustion.

Why the change in anatomy?  Was RNA or DNA in a virus from space? Maybe it was just weird person who had huge butt, and his genetic buttl got passed on to his future generation of long distance runners. 

Maybe others were trying to kick his ass, so he took off running and never stopped.

Well..... Young women have them so that they can fit them into tight leggings. 

Though perhaps some larger individuals should desist from this practice.

Just a personal observation....No sexism, genderism or sizism intended. 

For sure, some like them big.

And I also use them for storing rain water.....Butts, not leggings.