Editing Karl Ernst von Baer (section)

===Evolution===
[[File:Baer, Karl Ernst von – Über das Aussterben der Thierarten in physiologischer und nicht physiologischer Hinsicht überhaupt, 1863 – BEIC 10944358.jpg|thumb|''Über das Aussterben der Thierarten in physiologischer und nicht physiologischer Hinsicht überhaupt'', 1863]]
From his studies of comparative embryology, Baer had believed in the [[transmutation of species]] but rejected later in his career the theory of [[natural selection]] proposed by [[Charles Darwin]]. He produced an early tree-like branching diagram illustrating the sequential origins of derived character states in vertebrate embryos during ontogeny that implies a pattern of phylogenetic relationship.<ref>{{cite journal | last1 = Brauckmann | first1 = Sabine | year = 2012 | title = Karl Ernst von Baer (1792–1876) and Evolution | journal = Int. J. Dev. Biol. | volume = 56 | issue = 9| pages = 653–660 | doi=10.1387/ijdb.120018sb| pmid = 23319342 | doi-access = free }}</ref>

In the fifth edition of ''[[On the Origin of Species]]'' published in 1869, Charles Darwin added a ''Historical Sketch'' giving due credit to naturalists who had preceded him in publishing the opinion that species undergo modification, and that the existing forms of life have descended by true generation from pre-existing forms. According to Darwin:

:"Von Baer, towards whom all zoologists feel so profound a respect, expressed about the year 1859... his conviction, chiefly grounded on the laws of geographical distribution, that forms now perfectly distinct have descended from a single parent-form."<ref>[http://www.talkorigins.org/faqs/origin/preface.html "The Origin of Species"] {{Webarchive|url=https://web.archive.org/web/20151029190821/http://www.talkorigins.org/faqs/origin/preface.html |date=29 October 2015 }}. Preface to the Third Edition.</ref> He was a pioneer in studying biological time – the [[Time perception|perception of time]] in different organisms.<ref>Karl Ernst von Baer, Welche Auffassung der lebenden Natur ist die richtige?, Berlin, 1862</ref>

Baer believed in a [[Teleology|teleological]] force in nature which directed evolution ([[orthogenesis]]).<ref>Barbieri, Marcello. (2013). ''Biosemiotics: Information, Codes and Signs in Living Systems''. Nova Science Publishers. p. 7. {{ISBN|978-1-60021-612-1}}</ref><ref>Jacobsen, Eric Paul. (2005). ''From Cosmology to Ecology: The Monist World-view in Germany from 1770 to 1930''. p. 100. Peter Lang Pub Inc. {{ISBN|978-0-8204-7231-7}}</ref>