The World's Hardest Riddle

Something to do with age / time?

TIME
The time has come,
winter is here
and those yellow bears disappear.

The time has past
as man looks back with a sigh
and a tear in his eye.

As time is held
boys cross their legs
but of course the toilet begs

As time marches on
Girls loose their blush
and swap a comb for their brush

As time passes
For those held high
their end is nigh

As time catches up
Everyone is equal
when we get to the final sequel

As time turns
Without it we have flour and water
With it we have breakfast for my daughter

As time revolves
How does one turn water and wine
into something so fine

As time runs out
The more in a minute you try and squeeze
the less you can do with ease.

As time ticks
All the time that has past
man cannot comprehend something so vast.

So I guess the answer is time

but time does not cause these things. Time is relative anyway.

I have a puzzle for you

What has spines but no legs
leaves that do not fall
wisdom that it cannot speak
and wood which cannot grow?

To the original riddle: How does that turn polar bears white? And pancakes brown? I'll go with the 'time' solution. Also because that was my guess too