Book review of Ivan Schmalhausen

Ivan Schmalhausen:
FACTORS OF EVOLUTION (Blakiston, 1949)
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By reviewing a wealth of biological data, Schmalhausen advanced the theory that evolution is a process of hierarchical construction: differentiation yields increasing specialization and diversification of parts, while integration yields the creation of more stable and integrated forms of organization (specifically, the formation of new aggregates in which the structure and fuction of parts are subordinated to and regulated by the structure and function of the whole). For this to happen, genetic variation cannot be completely random but must be regulated by a genetic system of genetic systems (analogous to Waddington's "canalization" process).
The forces of natural selection can be divided into mobile and stabilizing. The former reshapes the individual to continously cope with the environment. The latter preserves the structure and function of organization by producing new forms of ontogenesis which are less vulnerable to the action of the environment. At the beginning, life was at the mercy of accidental environmental changes. Over evolutionary time, organisms became more and more independent of their environment, controlling their own function and structure (emergence of internal regulating mechanisms counteracting the action of the environment). Finally, organisms became able to determine their relationship with the environment. This progression is due to the growing importance of the role of stabilizing selection.