Once things were cool, microscopic aquatic animals appeared and then evolved into bigger ones that could eat their former colleagues. These creatures evolved over millions of years into fish, reptiles, birds, dinosaurs, mammals and lawyers.
Actual humans have only been around for a couple of million years, a pitifully small amount of time in evolutionary terms. Yet somehow the species has managed to become differentiated into various racial and ethnic strains, professions, religious affiliations and sexual proclivities.
In particular, this process has somehow produced both me and the idiot who cut me off on the Mass. Turnpike this morning.