basically

the creation of life on this planet
came on a molecular scale

a sequence was changed many times
and sometimes that creation adapted
in it's own environment into something
else, it's survivability ratio increased

so not all things we see today are what they
originally started out as

there was an adaptation period

some life forms did not survive at all
and some died much later after creation

so you can't call the creation process
of this planet PERFECT

if it was perfect, then certain species
would not have went extinct

not counting mass ELE's
Extinction Level Events

as the sea creations seemed to fair far
better than land creatures after an ELE

Argento