In 1934, Blum, in his “A Consideration of Evolution from a Thermodynamic View-Point”, introduced his so-called "chemical peneplanation" model of evolution, which he says yields a "directing factor" that is theologically free or "outside of the theological doctrine". Blum cites Lawrence Henderson (1913) and Gilbert Lewis (1923), to outline a coupling theory plus free energy decrease based theory of an orthogenesis conceptualized evolution, in the form of what he refers to as "chemical peneplanation", i.e. an synonym the semi-modern term Gibbs landscapes.
In 1950, Blum, in his Time’s Arrow and Evolution, presented his take on organic evolution based on the second law of thermodynamics.
In In 1922, Blum completed his AB in zoology, with a publication “On the Effect of Low Salinity on Teredo Navalis” (Ѻ), at the University of California, Berkeley. He then attended attended Harvard Medical School from 1923 to 1924, after which, in 1927, he completed a PhD in physiology at UC Berkeley. He then he worked as professor of animal biology at the University of Oregon, then as an instructor of physiology at Harvard Medical School, then an associate professor of physiology at the UC Berkeley. Most of his work was on irradiation experiments on mice and cancer.
Quotes | On
The following are quotes on Blum:
- “Evolution, says Blum, did not begin with the formation of the first life, nor was the origin of life a precise event. From the beginning of the universe, physical and chemical laws have inexorably channeled the course of evolution, so that possibilities were already limited during the time when the first life emerged.”
- — David Forrest (2012), “Review: Time’s Arrow and Evolution” 
Quotes | By
The following are quotes by Blum:
- “Practically since its first definitive formulation by Darwin the concept of chance variation and natural selection has dominated the study of evolution, although frequent attempts have been made to replace or modify it. Probably most such attempts are provoked by a vaguely defined awareness of an insufficiency in the natural selection hypothesis, and the recognition of a directive factor in evolutionary processes which persists through successive generations. The latter concept which is commonly known as ‘orthogenesis’, is supported a by considerable amount of evidence (Leo Berg, 1926), but at present is not widely accepted among biologists. The general reason for abandoning or neglecting this concept has been the failure, thus far, to demonstrate the existence of the necessary directing factor outside of the theological doctrine; and one may suspect that fear of leaning too closely to such doctrine has caused most biologists to ‘shy off’ from orthogenesis. It will be the aim of the writer to indicate the actual existence of a directing factor in evolutionary processes, while at the same time avoiding all necessity of invoking theological concepts.”
- — Harold Blum (1935), “A Consideration of Evolution from a Thermodynamic Viewpoint” 
- Chemical peneplanation – Hmolpedia 2020.
- Blum, Harold F. (1934). “A Consideration of Evolution from a Thermodynamic View-Point” (abs) (pdf), presented at the 94th meeting of the American Association for the Advancement of Science, Jun 20, in: The American Naturalist, 69(723):354-69, Jul-Aug, 1935.
- Blum, Harold F. (1968). Time’s Arrow and Evolution. Princeton, 2015.
- Forrest, David. (2012). “Review: Time’s Arrow and Evolution” (WB), Innovation Watch, Blog.
- Blum, Harold. (1941). Photodynamic Action: and Disease Caused by Light. Reinhold.
- Harold Blum – Hmolpedia 2020.