In 1970 he announced his programme of "Konstruktions-Morphologie" where he stressed the importance of three factors in determining the form of organisms: ecological/adaptive aspects; historical/phylogenetic aspects; and architectural/constructional aspects. The latter two factors are important sources of biological constraints; both acknowledging that both history and constructional principles place limits on what may be achieved in at least the short term of evolution. Such a view was influential on later workers such as Stephen Jay Gould and Richard Lewontin, such as their famous paper on "spandrels" that criticized panadaptionist accounts of evolution and form.