Charles DarwinBefore Darwin: Aristotle: compendium of natural historySpecies distinct from each otherEarly naturalists classified life’s diversity:Carl Linnaeus (1707-78): the father of modern taxonomy. He’s known for classifying nomenclature. At this time, it was a major advanced in categorizing species. Before Darwin: Species not linked to family tree, all species separately created, earth was young (6000 years old), and humans were separate from nature- not animalsChanges in the air:Although Darwin’s theory ran contrary to current thinking, changes in the air in many ways during his lifetimeFrench Revolution (people started seeing that change was important- natural world and the social world could be different than earlier beliefs)Industrial RevolutionScientific RevolutionThe EnlightmentEvolution before Darwin: - Nicolaus Steno (1600s) - realized that fossils were the remains of living organisms, transformed into stone- Geology- catastrophism (Series of catastrophes that changed geological things) vs uniformitarianism (slow changes in the universe eventually showing changes in geology, over a LONG period of time)- James Hutton (1800s) - slow changes could give rise to geological features given enough time- ancient age of the earth- William Smith (1800s) - specific sets of fossils characteristic of specific geological formations- Charles Lyell (1800s) - The Principles of Geology- doctrine of uniformitarianism - Georges Buffon (1700s) - ancient earth- gradual change in living forms (evolution)- Georges Cuvier (1800s) - Fossils- remains of extinct species-extinction common. He did NOT believe in evolution, he thought things were created separately but he contributed to our understanding of changes over time and extinction- Jean Baptiste Lamarck (1700s-1800s) – Inheritance of acquired characters. He argued that as things evolved in parents that it would be passed on to their children (ex giraffes and long necks vs short necks)- Erasmus Darwin- Darwin’s grandfatherDarwin as a Young Man: - Born in England and was studying to become a preacherLaying the Groundwork- James Hutton and Charles Lyell: proponents of uniformitarianism: one can understand geologicalfeatures changes gradually. Earth had undergone vast geological changes, impossible to produce in a short period-During Darwin’s youth geology captured the public’s (& Darwin’s) imagination. - Darwin attended Cambridge- worked with famous botanist JS Henslow and the famous geologist A. Sedwick-Darwin was asked by Captain Robert Fitzroy to go on a five year journey around the world- charting coastal waters- 1831. (Darwin was 22). They went on the voyage of the Beagle. It was a 5 year journey. He collected massive amounts of specimens. He was strongly influenced on the diversity of life while on this trip. -Famously, he was fascinated by the variations in forms of different animals that he found in the Galapagos Islands. Animals and plants showed distinctive differences (some birds were flightless, etc.). -Galapagos mockingbirds- stimulated Darwin to think about the nature of species. At first Darwin thought all the different mockingbirds were just varieties of birds, he didn’t realize they were of the same species-“What if these varieties grew to be so different they actually became separate species?” -Insights from Geology:- The Immensity of Time-Environmental Change-Continuity between the past and present -Darwin was impressed by the evidence of geology. He could see that there were fossils (including marine fossils) embedded in different layers of the earth. He concluded that over large amounts of time that environmental changes occurred. -Key facts from the fossil record:- Animal and plant forms have changed over time. The timespan of evolution is immense. Extinction is the fate of most species that have ever existed, environments in every locale have changed, often dramatically so.-Darwin returns:-During the five years, Darwin made careful observations of flora, fauna, and geology, and collected thousands of specimens. This established his reputation as a naturalist. -He secretly wrote in notebooks his ideas on evolution because in general, most people would not accept the idea of evolution. -He wrote The Origin of Species, which was eventually published, but it took a long time.TWO MAJOR THEMES: Natural selection & common descent-He drew phylogenetic trees to help show how many different species can arise and how many go extinct. -Lamarck: he viewed evolution as individual progression, with separate lineages. -Darwin: viewed evolution as a branching tree of life, he thought we all had a common descent. Different lineages form and evolved which would eventually turn into separate species but that we were all linked to a common descent. He showed hierarchical patterns of relatedness.Darwin: Empirical Research:-Coral reef atolls, barnacles, earthworms, chickens & orchids. -He realized that you can view nature as a source of selection. Population divergence & speciation. -In 1838 he read “Essay on Population” by Thomas Malthus. Malthus argued that human populations could quickly outstrip the food supply; competition for food or space was a constant force keeping populations on check. Darwin applied this idea to the natural world. More animals were born hat could survive & so there’s a struggle for food and space. Any plant or animal with a competitive edge (ex: drought tolerance) could live longer and leave more offspring than its fellows. The presence of such adaptations controlled, in effect, which individuals would represent the species in the next generation. Now Darwin could see how variation could make a difference: individuals with useful traits, on average, survive to reproduce and pass along those traits. A “contest” to reproduce. Darwin’s Logic: Since more individuals are produced than more can be supported by the available resources but population size remains stable, it means that there must be a fierce struggle for existence among the individuals of a population, resulting in the survival of only a part, often a very small part, of the progeny of each generation. - Inference 2: Survival in the struggle for existence is not random but depends in part on the hereditary constitution of the surviving individuals. This unequal constitutes the process of natural selectiono Inference 3: over the generations this process of natural selection will lead to a continuing