"'We are the serpent.'" (A World Named Cleopatra, New York, 1977, p. 57)
In Anderson's "The High Ones," it has to be deduced that bipeds with technology including spaceships and a computer are no longer intelligent.
In Anderson's "Wings of Victory," it has to be deduced that winged beings on the planet Ythri are intelligent, in other words that their bodies can generate enough energy to sustain both flight and intelligence.
In these and many other examples, sf resembles detective fiction. Explorers find puzzling, apparently inconsistent, clues and evidence on a newly discovered planet, then deduce the course that biological and social evolution have taken in this different environment.