AP Biology CHAPTER 1& 2 PROFESSOR SOLIS The Scientific Method Relies on empirical knowledge (experiment or observation) Develop an hypothesis (provisional explanation) Identify a research question and then gather information to answer it. The Development of Evolutionary Theory Throughout the Middle Ages the European worldview was that all aspects of nature (and their relationship to one another) never changed. Life forms couldnt and didnt change This is known as the belief in the Fixity of the Species The Scientific Revolution What transformed centuries old belief in a static world, to belief in one that is in continuous motion? Age of exploration allowed for the growing interest in human diversity Other traditional beliefs were being called into question Copernicus and Galileo challenge Aristotles geo centric view of the world by the helio centric view challenges the Catholic Church (dominant ruling body during the Middle Ages and the Renaissance) Age of the Naturalists John Ray (16th century - British). Began with the classification of plants. Discovered that certain species of plants share characteristics of other species of plants. Groups of plants and animals could be differentiated from other groups by their ability to mate with one another. Coined the term species. Reproductively Isolated: Pertaining to groups of organisms that, mainly because of genetic differences, are prevented from mating and producing offspring with members of other groups. Age of the Naturalists contd. Carolus Linnaeus(18th century Sweden). Best known for developing a classification of plants and animals, Systema Naturae (Systems of Nature) first published in Built upon Rays system of classification, but added humans to the classification of animals. By doing so, he recognized humans as being part of the natural world, and thereby subject to the same laws of nature. This was a profound breakthrough during this time. (believed in fixity of species) Established, binomial nomenclature convention of using genus and species names to refer to a species (Homo sapiens) Established, taxonomy: The branch of science concerned with the rules of classifying organisms on the basis of evolutionary relationships. Age of the Naturalists contd. Comte de Buffon (Georges Louis Leclerc 18th century - French). Buffon did not believe in the perfection of nature, nor even that nature had a purpose, but he did recognize the relationship between the external environment and living forms. Wrote Natural History published in (culture can be influenced by environmental conditions) Age of the Naturalists contd. Erasmus Darwin (18th century British). Laid the foundation for his grandson Charles Darwins work on natural selection. Erasmus expressed these ideas and commented on human evolution. Jean Baptiste-Lamarck (18th century French). Believed that species change was influence by environmental changes. He is best known for the theory of the inheritance of acquired characteristics. But he didnt get it quite right! Age of the Naturalists contd. Georges Cuvier (18th century French). Vertebrate paleontologist. Adamantly insisted on the fixation of the species. Cuvier explained the fossil record as the result of a succession of catastrophes followed by new creation events. (proposed the concept of catastrophism) Age of the Naturalists contd. Charles Lyell (18th & 19th century British). Considered the founder of modern geology. Observed that the geologic processes that are observed in the present: earthquakes, volcanic eruptions, floods, water erosion, etc.; are the same as those that have occurred in the past. These processes create the geologic landscape we see today. Principles of Geology Uniformitarianism: The theory that the earths features are the result of long term processes that continue to operate in the present as they did in the past. Opposed catastrophism and contributed strongly to the concept of immense global geologic time. i.e. aspects of the earth are variable, but the processes are constant Proposed the earth to be far older than anyone had previously suspected. (4.54 billion years) Age of the Naturalists contd. Thomas Malthus (18th century British) Essay on the Principle of Population. Malthus pointed out that if not kept in check by limited food supplies, human populations could double in size every 25 years. That is, population size increases exponentially, while food supplies remain relatively stable. Age of the Naturalists contd. Charles Darwin (19th century British) Principle of natural selection. Did not suggest human evolution. Restricted his theory to plants and animals. Survival of the Fittest those with characteristics best suited to their environment have the best chance of surviving, producing offspring and populating that geographical region. Those less suited, will not be able to procure resources and will die out. Set sail on HMS Beagle December 17, Travels to South America, observes giant tortoises, finches, and fossils of large extinct mammals Evolution was originally termed, transmutation the change of one species to another. (original proponents were anti-Christian no doubt giving rise to opposition persistent today) Darwin contd. Set sail on HMS Beagle December 17, Travels to South America, observes giant tortoises, finches, and fossils of large extinct mammals Evolution was originally termed, transmutation the change of one species to another. (original proponents were anti- Christian no doubt giving rise to opposition persistent today) Natural Selection Darwin realizes the key to evolution is natural selection. What is Evolution? A change in the genetic structure of a population. The term is also frequently used to refer to the appearance of a new species Natural Selection 1. All species are capable of producing offspring at a faster rate than food supplies increase. 2. There is biological variation within all species 3. Each generation produces more offspring than can survive; there is competition among individuals. 4. Individuals who have favorable traits or variations have an advantage over those who dont. (i.e. fitness) Natural Selection 5. The environmental context determines whether a trait is favorable. 6. Traits are inherited and passed on to the next generation. 7. Over long periods of geologic time, successful variations accumulate in a population, so that later generations may be distinct from ancestral ones. In time, a new species may occur Natural Selection 8. Geographical isolation also contributes to the formation of new species. As species become geographically isolated, they begin to adapt to different environments. Over time, populations respond to selective pressures. Selective pressures: Forces in the environment that influence reproductive success in individuals. Natural Selection in Action Peppered Moths of Britain Natural Selection in Action Resistant strains of disease causing microorganisms in humans 1940s introduction of antibiotics Bacteria possesses genetic variability Bacteria produces new generation every few hours Natural Selection in Action Fundamentals of Evolutionary Change: 1. A trait must be inherited if evolution is to act on it. 2. Natural selection cant occur without population variation in inherited characteristics 3. Fitness is a relative measure that changes as the environment changes. 4. Natural selection can act only on traits that affect reproduction. Fertility is important- more births = more genes passed on. Constraints on 19 th Century Evolutionary Theory Darwin argued for the concept of evolution in general He didnt know the exact mechanisms of change He didnt know the source of variation He believed inheritance was a blending process by parents to offspring Constraints on 19 th Century Evolutionary Theory 20 th Century: Gregor Mendels (Austrian monk) and Darwins theory of natural selection come together 1953 Watson and Crick discover DNA New discoveries: sequencing of the human genome Entire genetic makeup of an individual or species Opposition to Evolution Today Debate over Evolution continues. Religion and science concern different aspects of the human experience There arent simple answers to complex questions As biological organisms we are subject to evolution, variation, and adaptation Physical Anthropology is in part human biology seen from an evolutionary perspective Macro evolution large scale changes that happen over successive generations Micro evolution small genetic changes that occur within a species