page_title: Orthogenesis
section_title: With Darwin
hierarchical_section_title: Orthogenesis / History / With Darwin
caption_attribution_description: Diagram of the evolution of Titanothere horns. Top to bottom: Brontotherium, Protitanotherium, Manteoceras, Eotitanops.[1]
context_page_description: Orthogenesis, also known as orthogenetic evolution, progressive evolution, evolutionary progress, or progressionism, is the biological hypothesis that organisms have an innate tendency to evolve in a definite direction towards some goal due to some internal mechanism or "driving force". According to the theory, the largest-scale trends in evolution have an absolute goal such as increasing biological complexity. Prominent historical figures who have championed some form of evolutionary progress include Jean-Baptiste Lamarck, Pierre Teilhard de Chardin, and Henri Bergson.
  The term orthogenesis was introduced by Wilhelm Haacke in 1893 and popularized by Theodor Eimer five years later. Proponents of orthogenesis had rejected the theory of natural selection as the organizing mechanism in evolution for a rectilinear model of directed evolution. With the emergence of the modern synthesis, in which genetics was integrated with evolution, orthogenesis and other alternatives to Darwinism were largely abandoned by biologists, but the notion that evolution represents progress is still widely shared.
context_section_description: Ruse observed that "Progress (sic, his capitalisation) became essentially a nineteenth-century belief. It gave meaning to life—it offered inspiration—after the collapse [with Malthus's pessimism and the shock of the French revolution] of the foundations of the past."
  The Russian biologist Karl Ernst von Baer (1792–1876) argued for an orthogenetic force in nature, reasoning in a review of Darwin's 1859 On the Origin of Species that "Forces which are not directed—so-called blind forces—can never produce order." 
  In 1864, the Swiss anatomist Albert von Kölliker (1817–1905) presented his orthogenetic theory, heterogenesis, arguing for wholly separate lines of descent with no common ancestor.
  In 1884, the Swiss botanist Carl Nägeli (1817–1891) proposed a version of orthogenesis involving an "inner perfecting principle". Gregor Mendel died that same year; Nägeli, who proposed that an "idioplasm" transmitted inherited characteristics, dissuaded Mendel from continuing to work on plant genetics. According to Nägeli many evolutionary developments were nonadaptive and variation was internally programmed.  Charles Darwin saw this as a serious challenge, replying that "There must be some efficient cause for each slight individual difference", but was unable to provide a specific answer without knowledge of genetics. Further, Darwin was himself somewhat progressionist, believing for example that "Man" was "higher" than the barnacles he studied.
  Darwin indeed wrote in his 1859 Origin of Species:
  The inhabitants of each successive period in the world's history have beaten their predecessors in the race for life, and are, insofar, higher in the scale of nature; and this may account for that vague yet ill-defined sentiment, felt by many palaeontologists, that organisation on the whole has progressed. [Chapter 10]
  As all the living forms of life are the lineal descendants of those which lived long before the Silurian epoch, we may feel certain that the ordinary succession by generation has never once been broken, and that no cataclysm has desolated the whole world. Hence we may look with some confidence to a secure future of equally inappreciable length. And as natural selection works solely by and for the good of each being, all corporeal and mental endowments will tend to progress towards perfection. [Chapter 14]
  In 1898, after studying butterfly coloration, Theodor Eimer (1843–1898) introduced the term orthogenesis with a widely read book, On Orthogenesis: And the Impotence of Natural Selection in Species Formation. Eimer claimed there were trends in evolution with no adaptive significance that would be difficult to explain by natural selection. To supporters of orthogenesis, in some cases species could be led by such trends to extinction. Eimer linked orthogenesis to neo-Lamarckism in his 1890 book Organic Evolution as the Result of the Inheritance of Acquired Characteristics According to the Laws of Organic Growth. He used examples such as the evolution of the horse to argue that evolution had proceeded in a regular single direction that was difficult to explain by random variation. Gould described Eimer as a materialist who rejected any vitalist or teleological approach to orthogenesis, arguing that Eimer's criticism of natural selection was common amongst many evolutionists of his generation; they were searching for alternative mechanisms, as they had come to believe that natural selection could not create new species.
caption: Henry Fairfield Osborn's 1934 version of orthogenesis,  aristogenesis, argued that aristogenes, not mutation or natural selection, created all novelty.[28] Osborn supposed that the horns of Titanotheres evolved into a baroque form, way beyond the adaptive optimum.[29]
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