[4] The biologist James H. Birnie praised the book commenting "it is obvious that the author has kept his personal opinions in the background and has considered the data without bias.
"[6] Criticism came from the botanist Conway Zirkle who commented in a 1954 review "there is no evidence presented [that] the author has understood or digested the great advances made in evolutionary theory during the past twenty years."
Glass wrote that the book was too uncritically accepting of Lamarckism, orthogenesis and John Christopher Willis' age and area hypothesis whilst ignoring evidence of their refutation.
[8] The biologist Ernst Mayr wrote that the "book suffers from an overzealous belief in the inheritance of acquired characters [but] is most useful for a sympathetic account of neo-Lamarckians.
The book received a positive review from John C. Green who noted "The evidences of evolution are marshalled in a clear and orderly fashion, with abundant reference to the scientific literature.