'from the paramecium to the human race

all life forms are meticulously organised

sophisticated aggregates

of evolving microbial life

bacteria occupy and are indispensable 

to every known living structure on the Earth today

having survived in an unbroken line

from the beginnings of life

all organisms today are equally evolved'

Lynn Margulis & Dorion Sagan : 'Microcosmos' p28