1. Evolution How does that work again?

2. Origins of Life Scientists have long wondered where life first began. Scientists have long wondered where life first began. Fossil and chemical evidence has led to the knowledge that single-celled organisms were the first forms of life in an atmosphere full of toxic gases. Fossil and chemical evidence has led to the knowledge that single-celled organisms were the first forms of life in an atmosphere full of toxic gases.

3. So what happened after that? From that soup, life began and continued. From that soup, life began and continued. The early organisms continued to reproduce and made offspring that looked or acted different. The early organisms continued to reproduce and made offspring that looked or acted different. We all started using proteins, breaking down sugar, etc. We all started using proteins, breaking down sugar, etc. Humans, though, still had a lot to learn about how organisms reproduced to make new ones. Humans, though, still had a lot to learn about how organisms reproduced to make new ones.

4. Take a look at how we thought bees were made Weird huh? Yes, we were that stupid once! Weird huh? Yes, we were that stupid once! But think about it: we knew that bees weren’t human and didn’t reproduce sexually, so this was a good replacement. But think about it: we knew that bees weren’t human and didn’t reproduce sexually, so this was a good replacement. Experiments by Redi and Pasteur determined that organisms must come from other living organisms. Experiments by Redi and Pasteur determined that organisms must come from other living organisms.

5. Experiments Redi proved that flies do not come from rotting meat. Redi proved that flies do not come from rotting meat. Pasteur proved conclusively that spontaneous generation does not occur. Pasteur proved conclusively that spontaneous generation does not occur.

6. Natural Selection Darwin’s travels led him around the world. His most important work was done in the Galapagos islands. Darwin’s travels led him around the world. His most important work was done in the Galapagos islands. In studying the endemic organisms and comparing them to those he already knew, he began to wonder why they were so similar. In studying the endemic organisms and comparing them to those he already knew, he began to wonder why they were so similar.

7. Natural Selection Natural selection is not evolution in itself. Natural selection is not evolution in itself. Natural selection gives the means by which evolution occurs. Natural selection gives the means by which evolution occurs. In other words, scientists think that evolution occurs because of natural selection. All of the evidence points in this direction.

8. Natural Selection Darwin’s ideas had four basic steps: 1. Organisms produce more offspring than can survive. 2. In any population, individuals have variations. 3. Individuals with certain useful variations survive in their environments and pass these variations on to their children. 4. Over time, these variations make up most of the population. These organisms can look completely different from their ancestors.

9. So What Does This Mean? It means that organisms have developed special adaptations that are necessary to survive in their environments according to natural selection. It means that organisms have developed special adaptations that are necessary to survive in their environments according to natural selection. Can you think of any organisms that have special adaptations to help them survive? Can you think of any organisms that have special adaptations to help them survive?

10. This sounds fishy to me, Bass! Remember, evolution is a science and only presents what we know so far! Remember, evolution is a science and only presents what we know so far! By combining what we know about early Earth and how natural selection works, we can make a hypothesis about how life got here. By combining what we know about early Earth and how natural selection works, we can make a hypothesis about how life got here. Do we know how life got started – NO! That’s why I can’t say your religion is wrong! Do we know how life got started – NO! That’s why I can’t say your religion is wrong! But we do have some ways to know that we all came from a similar origin. But we do have some ways to know that we all came from a similar origin.

11. Evidence for evolution Organisms can develop metabolic changes over time. Bacteria and viruses often evolve and our remedies won’t be as effective. Organisms can develop metabolic changes over time. Bacteria and viruses often evolve and our remedies won’t be as effective. Artist rendition of flesh eating disease.

12. Evidence for Evolution Mimicry Mimicry When an organism has a structural adaptation that makes it appear like another organism. When an organism has a structural adaptation that makes it appear like another organism. These organisms have mutations that allow them to act like other organisms. These organisms have mutations that allow them to act like other organisms. What kind of animal is this? Do you see an animal here?

13. Here are some more examples

14. Evidence for Evolution: Coloring Camouflage Camouflage When an organism has an adaptation that lets them blend in to their surroundings. When an organism has an adaptation that lets them blend in to their surroundings. These organisms have mutations that let them look like other things in the environment. These organisms have mutations that let them look like other things in the environment. Where is the lizard? Who’s here?

15. Other Evidence Fossils are remains of organisms from long ago and are found in different layers of rock. Fossils can be any of these: A. Cast C. Trace B. Imprint

16. Fossils We know that there were other organisms on Earth because we have found their fossils. We know that there were other organisms on Earth because we have found their fossils. We can find their approximate age by dating the rock they were found in. We can find their approximate age by dating the rock they were found in. Each fossil tells us something about the organism. Each fossil tells us something about the organism.

17. What we’ve learned from fossils We know that the oldest living organisms came from the sea. We know that the oldest living organisms came from the sea. We know that there was a period when all life died out (~ 144 million years ago). We know that there was a period when all life died out (~ 144 million years ago). We know where certain organisms lived and what earlier ancestors looked like. We know where certain organisms lived and what earlier ancestors looked like.

18. Anatomy There are two types of structures that suggest evolution. There are two types of structures that suggest evolution. Homologous structures: Homologous structures: Remembering that homologous means same, this is when organisms have the same or similar body structures. For example, most animals have hands. Remembering that homologous means same, this is when organisms have the same or similar body structures. For example, most animals have hands.

19. Anatomy Analogous structures Analogous structures These structures are found in different animals and are not similar in structure, but have the same function. These structures are found in different animals and are not similar in structure, but have the same function.

20. Embryology Embryology deals with the development of the embryo. Take a look at the next slide. What kinds of organisms do you see? What do you notice about them? Embryology deals with the development of the embryo. Take a look at the next slide. What kinds of organisms do you see? What do you notice about them? Although the pictures here are exaggerated and they are no longer used as proof by itself, there are still many similarities between the species. Although the pictures here are exaggerated and they are no longer used as proof by itself, there are still many similarities between the species.

22. Biochemistry Biochemistry evidence for evolution is based on DNA evidence. Biochemistry evidence for evolution is based on DNA evidence. Scientists use electrophoresis to determine similarities between organisms. Scientists use electrophoresis to determine similarities between organisms. Organisms with similar DNA are more closely related. Organisms with similar DNA are more closely related. Biologists used this information to create the 6 th Kingdom (Archaebacteria) because they were so different from other kinds of bacteria. Biologists used this information to create the 6 th Kingdom (Archaebacteria) because they were so different from other kinds of bacteria.

23. So why did you make us study genetics and what does it have to do with evolution? Remember that organisms with useful variations survive and pass on their genes. Remember that organisms with useful variations survive and pass on their genes. Useful variations are those that help them hide from predators or get food. Useful variations are those that help them hide from predators or get food. These variations are differences in their genes. These variations are differences in their genes.

24. What do genes have to do with it? Each species has a specific group of characteristics or a gene pool. Each species has a specific group of characteristics or a gene pool. As organisms breed, they pass along these genes. The genotypes don’t change much which means the phenotypes don’t change much. As organisms breed, they pass along these genes. The genotypes don’t change much which means the phenotypes don’t change much. If a new genotype (a different phenotype) is introduced to the population, it could possibly be bred out of the gene pool if it doesn’t help survival. If it helps survival, then it may stay in the gene pool. If a new genotype (a different phenotype) is introduced to the population, it could possibly be bred out of the gene pool if it doesn’t help survival. If it helps survival, then it may stay in the gene pool.

25. So what? New variations or phenotypes are caused by different genotypes that weren’t found in the gene pool before (either by mutation or an organism new to the area). New variations or phenotypes are caused by different genotypes that weren’t found in the gene pool before (either by mutation or an organism new to the area). If these new genotypes are popular and are bred into the population, they will stay in the gene pool and you’ll begin to see them more. If these new genotypes are popular and are bred into the population, they will stay in the gene pool and you’ll begin to see them more.

26. I still don’t get it, Ms. Bass! Okay, what would happen if a group of blond haired people moved to Asia and people thought that blond hair was cool? Okay, what would happen if a group of blond haired people moved to Asia and people thought that blond hair was cool? When the parents have children, they will introduce blond hair into the gene pool. (Bb) When the parents have children, they will introduce blond hair into the gene pool. (Bb) If children from these families have children, there is a possibility that they could have blond hair, introducing the blond phenotype to the population. If children from these families have children, there is a possibility that they could have blond hair, introducing the blond phenotype to the population. BBbb Family 1 BBbb Family 2 Bb bb