Functions and Forms

me thinks that function follows form
not just the other way around
the two are intricately bound
each has its duties to perform
in fact, it followed form at first
cupping our hands to sate our thirst
those early tools, a rock, a stick
arose before we learned the trick
of shaping nature to our needs
creating forms where none had been
or digging ditches for our seeds
and all that happened in between
the hammer that you hold indeed
perhaps the optimal of shapes
a heavy rock would do the deed
just ask our cousins, the great apes

and so my friend, this contribution:
they're in convergent evolution