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Life’s Diversity through Evolution Science vs. Religion What is science based on? Science is based on OBSERVABLE evidence. What is religion based on? Religion is based on FAITH. – By definition, faith is something that is not observable. Since they are 2 different “fields,” they are not competing with each other Religious Scientists? “My religion consists of a humble admiration of the illimitable superior spirit who reveals himself in the slight details we are able to perceive with our frail and feeble mind.” – Albert Einstein (1879 - 1955) “Science without religion is lame, religion without science is blind.” – Albert Einstein (1879 - 1955), "Science, Philosophy and Religion: a Symposium", 1941 Religious Scientists? “Not only does God play dice, but... he sometimes throws them where they cannot be seen.” – Stephen Hawking “In my view, there is no conflict in being a rigorous scientist and a person who believes in a God who takes a personal interest in each one of us. Science’s domain is to explore nature. God’s domain is in the spiritual world, a realm not possible to explore with the tools and language of science. It must be examined with the heart, mind and soul.” – Francis Collins, Director of Human Genome Project Evolution is a Theory Theory Defined: “scientific principle to explain phenomena: a set of facts, propositions, or principles analyzed in their relation to one another and used, especially in science, to explain phenomena” – MSN Encarta, http://encarta.msn.com/dictionary_/theory.html Evolution is as much a theory as… – Cell theory: biology – Atomic theory: chemistry – Plate tectonic theory: geology A Final Quote “Be opinionated, just not ignorant.” Evolution The theory that organisms on Earth have changed over time is known as evolution. Charles Darwin (1809-1882) is the man who contributed more to our understanding of evolution than any other individual. Charles Darwin English naturalist (1809-1882) 1831, Darwin took a job as a naturalist on the HMS Beagle – Went on a 5-year scientific journey around the world He collected many biological and fossil specimens – Combined with his previous and subsequent observations Published On the Origin of Species by Natural Selection in 1859 – These ideas are a basic unifying theme of biology today – Without evolution, biology doesn’t make as much sense He realized that he had never seen many of these organisms and the diversity of life on Earth was enormous! Darwin questioned “Where did all of these different life forms come from?” EX: Darwin collected 68 species of beetles from Brazil in just a few hours while on shore. Darwin also discovered many fossils of organisms that no longer existed today. This lead to other questions, “Where did all these organisms go? And why did they disappear?” Fitness Darwin observed that many plants and animals had parts and displayed behaviors that helped them survive. Traits and behaviors that will help organisms survive and reproduce in their environment give those organisms greater fitness (ability to survive and reproduce). Those organisms that are most fit will survive and reproduce more often than those organisms who are “less” fit. Became known as “survival of the fittest.” – Darwin did not use this phrase, it came about later & may cause misconceptions… Fitness Darwin argued that increased fitness arises from adaptations. Certain adaptations allow organisms to become better suited to their environment, and thus better able to survive and reproduce. Adaptations can be physical or behavioral Does “struggle for existence” mean only the biggest, strongest animals survive? What types of characteristics increases an organisms chance of surviving? Summary of Darwin’s Idea There is variation between individuals. Summary of Darwin’s Idea Organisms tend to have more offspring than can possibly survive, so there is competition among the offspring for a limited amount of resources Summary of Darwin’s Idea Organisms compete for limited resources There is a struggle for existence Summary of Darwin’s Idea Those organisms that are best suited for their environment (most fit) will survive and pass on their genes. Darwin’s Theory of Evolution Darwin developed evolution by natural selection Compared the process of natural selection in nature vs. artificial selection used by people. He used this comparison to develop a hypothesis to explain how evolution occurs. Using artificial selection a breeder can produce plants and animals that look very different from their ancestors. Artificial selection uses the variation nature provides. How does horse racing relate to selective breeding? Darwin’s Origin of Species He filled notebooks with ideas about species diversity & the process of evolution. His beliefs challenged the fundamental ideas of that time (species don’t change). Darwin was very reluctant to publish his book due to his fear of what the public would think. Are their any scientific topics today that are controversial? Origin of Species 1858, a naturalist name Alfred Wallace sent him a letter describing evolution. He had been working in Malaysia and come to the same conclusions Darwin did. Darwin had been working on his theory and the evidence to support it for 20 years. Darwin published the Origin of Species in 1859, 23 years after his trip. Why do you think Darwin waited to publish his book? Origin of Species His book did two things: 1. Proposed a mechanism for evolution (natural selection) 2. Evidence showing it had been taking place for millions of years and continues to take place Descent with Modification Over long periods of time, natural selection will start to produce organisms with different structures or organisms that occupy different niches or habitats. Because of this, species today look different from their ancestors. Geological Evolution – James Hutton (1788) proposed that rain, wind, temperature, and natural disasters shaped the valleys, mountains, and rocks over extremely long periods of time – Charles Lyell (1830) contributed to this by adding that current observations of volcanic eruptions and other natural disasters shows that Hutton was correct in assuming the Earth was older than originally predicted Acceptance of Geological Evolution Important to Darwin because it established an OLD Earth Darwin’s theory of evolution required lots of time Another important influence: Thomas Malthus – Observed that humans were being born at a faster rate than they were dying – War, famine, and disease control populations – These observations provided enough curiosity for Darwin to delve deep into his theory of Natural Selection humans evolve First placental mammals Flowering plants dominant First birds 1st dinosaurs First reptiles First seed plants First amphibians First vertebrates First invertebrates eukaryotes prokaryotes Life evolves Dating Techniques Geologic Record – Hypothetical library of all the known geological processes on Earth – Determined through inference and dating methods Relative Dating (hee hee) – Sediments are constantly being laid down. – Over time, many layers form – If a fossil is in a layer below a different fossil, it is older than that fossil Radiometric Dating Radiometric Dating – Radioactive isotopes decay and form new isotopes - the rate this happens is called the isotope’s half life – Ex: Potassium-40 decays to argon-40 and has a half life of 1.3 billion years Half a sample will decay to argon-40 in 1.3 billion years So if there are equal amounts of potassium-40 and argon-40 in an area, the sample has been in place 1.3 billion years – Carbon 14 has a half life of only 70,000 years for more recent sample dating Review 1. 2. 3. 4. How does the geologic record help us? What use is relative dating? What is radiometric dating? Why are different isotopes used in radiometric dating? Evidence for Evolution Fossil Record – A hypothetical “library” of all the fossils collected around the world Fossils show changes throughout time – 99 percent of all animals are now extinct – Fossil record shows ancestors with similar characteristics Embryology Study of embryos and the relationships that exist between different species Evidence for Evolution: Embryology Many species share features in the young embryos – Ex: Mammals, reptiles, birds and fish all have a tail and pharyngeal pouches (develop into different respiratory systems) Evidence For Evolution: Anatomy Homologous Structures are structural features with a common evolutionary origin – Ex: whale forelimb, crocodile forelimb, bird wing, human forelimb all look the same – Can you think of other examples? Analogous Structures are body parts or organisms that do not have a common evolutionary origin but are similar in function – Bird, bat and butterfly wings – Show how organisms adapt to different ways of life and different conditions Homologous Structures Structure and function between species is the same Analogous Structures Functions are the same between species; structures are different http://evolution.berkeley.edu/evolibrary/article/similarity_hs_01 Evidence for Evolution Vestigial Structures are body structures that no longer serve their original purpose, but was probably useful to an ancestor – Ex: human appendix, pelvic bone in baleen whale, “tail” in humans, some human’s ability to wiggle their ears Vestigial Structures Evidence shows the organ was once used, but not any longer Evidence for Evolution Biochemistry Nearly all organisms share DNA, ATP, and many enzymes among their biochemical molecules Organisms that share more similar enzymes, DNA sequences, etc. are more closely related Review 1. 2. 3. 4. 5. 6. How did Darwin come up with his ides for natural selection? Some snakes have vestigial legs. Why is this considered evidence for evolution? Explain how adaptations such as camouflage help species survive. How do homologous structures provide evidence for evolution? Why did birds and bats both get wings? A parasite that lives in red blood cells causes the disease called malaria. In recent years, new strains of the parasite have appeared that are resistant to the drugs used to treat the disease. Explain how this could be an example of natural selection occurring.