Together with Thomas Sebeok and Thure von Uexküll, he has developed a semiotic approach in biology (biosemiotics) in his works of the 1970s and 1980s.
Koos Thomas Sebeoki ja Thure von Uexkülliga arendas ta semiootilist lähenemist bioloogias (biosemiootikat) oma 1970ndate ja 1980ndate töödes.