Our cells have fluids that dont mix in gravity.... Change in orientation doesnt matter..

I just find it strange that the one constant in our evolution hasnt become essential....

I am not claiming there is any REASON behind the fact we dont need gravity, I just think it is odd, and darn lucky for us....

I can think of a few dozen ways it could be esential for life... but evolution hasnt gone that way.....

On earth we can expect maybe 2 seconds of free fall, after that we are dead w/o our technology...I had 40 seconds but had a parachute at the end....

to answer your question most animals do not have a problem with sun burn... we do because we have evolved the ability to cover up.... I think that, aside from our intelligence, we are the most defenseless of all large mammals... No hair no claws no teeth that would frighten anything larger than a hamster.... All we have is intelligence and tool making...that is it! Without intelligence we are free food for most predators...

You have to admit that it is odd that gravity, the one constant, seems to be a non issue......