The development of evolutionary theory What we know today Jan Feb Mar Apr MayJunJul Aug Sept Oct Nov Jan 1 Origin of Universe 13 7 Billion years ago Aug 15 Formation of Solar System 5 Billion years ago Sept 20 Origin of Life on Earth 3 8 Billion years ago What we know today December Early conceptualizations of nature Most religions talked about special creation and considered world to be young In 1500s a heliocentric solar system was proposed With respect to biology Fixity of species the Great Chain of Being traces back to Aristotle Early conceptualizations of nature Many scholars from various countries engaged in Taxonomy classification of different living things Early classifications usually focused on medicinal plants and were simple lists of plant types tree shrub etc Emperor Shennong 2696 BC classified medicinal plants Ebers Papyrus 1500BC from Egypt was a medical document that listed medicinal plant types Early conceptualizations of nature Furthermore numerous scholars from various regions had relatively advanced notion of evolutionary change For example numerous Muslim and Persian scholars discussed concepts of evolution Early conceptualizations of nature Ibn Miskawayh 930 1030 The animal world then widens its species become numerous and in a gradual process of creation it finally leads to man who is able to think and to reflect the level of monkeys and the like These become near to man in structure and human appearance There is no difference between those types and man except a little which if surpassed they become humans Ibn Khaldun 1332 1406 Early conceptualizations of nature The writings of these early scholars from outside of Europe were available available but not acknowledged unknown to known to but unavailable to Darwin Some of Darwin s influencers John Ray 1627 1705 First proposed that interbreeding organisms be called species And similar groups of species be called genera singular genus Fixity of species Some of Darwin s influencers Carolus Linnaeus 1707 1778 Also added class and order Best legacy was establishing a simple and ultimately universal classification scheme Worst legacy was classifying humans into different groups Implicitly challenged great chain of being Human Ape Monkey Some of Darwin s influencers George du Buffon 1707 1788 Ask me about nipples First suggested that species were not completely fixed they degrade A dynamic relationship between organisms and environment Believed world was old not young Some influential thinkers Organic Life began beneath the waves Hence without parent by spontaneous birth Rise the first specks of animated earth Erasmus Darwin 1731 1802 First proposed idea of the origin of species through evolution in Zoonomia a book in rhyming verse Common ancestry and life in the sea However did not have a mechanism for evolution Some of Darwin s influencers Jean Baptiste de Lamarck 1774 1829 I was poor and didn t get the credit I deserved Theory of evolution by inheritance of acquired characteristics first mechanistic theory of change Mechanism HOW it works Payed attention to heritability Some influential thinkers George Cuvier 1769 1832 Recognized that fossils could be grouped with modern organisms Older fossils were less like modern organisms than younger fossils Rejected the concept of evolution and argued for the fixity of species He believed in Catastrophism earth s history involved a series of biblical catastrophes such as floods Some of Darwin s influencers Charles Lyell 1797 1875 Many fossils showed gradual change over long periods of time deep time Thought earth was very very old Lyell introduced uniformitarianism past and current natural processes are one and the same Some of Darwin s influencers Thomas Malthus 1766 1834 Populations have the potential to increase at a faster rate than resources As a result there is intense competition among individuals Eugenicist Charles Robert Darwin 1809 1882 Born a naturalist Passionate naturalist throughout his life Background in medicine and theology Graduated from Cambridge University Developed reputation as solid naturalist The voyage of the Beagle Connections at Cambridge allowed him to join the crew on board the H M S Beagle The Beagle was commandeered by Capt Robert Fitzroy Darwin was the ship s naturalist Voyage lasted 5 years Capt Fitzroy Voyage of the Beagle First Stop South America Spent a lot of his time on land with the Beagle crew surveyed the coast Observed geologic as well as biological phenomena First tidbits of evidence began to emerge Fossil forms and Extinction Marine fossils in the Andes Implied long term geologic changes over time Also implied species go extinct But extinct forms resemble the extant forms Descent with modification The Galapagos Islands Noticed Lots of biological diversity and variation though islands broadly similar in environment Finches one mainland form many island forms Seeing this gradation and diversity of structure in one small intimately related group of birds one might really fancy that from an original paucity of birds in this archipelago one species had been taken and modified for different ends Ideas that inspired Darwin Malthus struggle for existence Lyell s uniformitarianism Past geological processes also operated today The earth is old populations vary nature is diverse A natural struggle for existence might operate Ideas that inspired Darwin A letter from Alfred Russel Wallace 1823 1913 those that die must be the weakest those that prolong their existence can only be the most perfect in health and vigor Also influenced by Malthus Ideas that inspired Darwin Artificial breeding could select for strains that differed notably from the original form Geographic variation hinted at local modification of a single species Observed anomalies or imperfections e g vestigal organs like your appendix and suggested they reflect a history of change In works on natural history rudimentary organs are generally said to have been created for the sake of symmetry or in order to complete the scheme of nature but this seems to me no explanation merely a restatement of fact