The crucibles that bore out early building blocks of life may have been, in many cases, modest puddles.
Viruses have proven to be wily foes. Attempts to fend off viruses causing even the common cold or flu have failed, and new viral outbreaks such as dengue, Ebola or Zika continue to elude drugs.
Touch a hot stove, and your fingers will recoil in pain because your skin carries tiny temperature sensors that detect heat and send a message to your brain saying, "Ouch! That's hot! Let go!"
All living things require proteins, members of a vast family of molecules that nature "makes to order" according to the blueprints in DNA.