Evolution Presenter notes: Evolution is one of the most important concepts in the Science of Biology. In fact Biology simply does not make sense without Evolution. Evolution is the idea that all living things arose from a single common ancestor in the distant past and that life continues to diversify today as new species appear. Evolution explains why we can classify organisms into different groups (because some organisms are more closely related than others). Evolution explains why the cells of all organisms use the same kind of biochemical machinery (because all life shares a common ancestor). This talk deals with the discovery of evolution, how evolution works, and the evidence for evolution.   Background note: A companion talk dealing with the History of Life from its earliest origins to the present day can be downloaded from the Your Planet Earth website: http://www.earth4567.com/talks/life.html. Although these two modules on Evolution and the History of Life can be delivered as stand-alone resources, they are best studied together. commons.wikimedia.org/wiki/Image:DNA_double_helix_vertikal.PNG commons.wikimedia.org/wiki/Image:Charles_Darwin_1881.jpg

The Tree of Life All living things _________________________ We can draw a Tree of Life to show how every __________is _____________. ______________refers to the ____________________________________________________________________________________ Presenter notes: All living things share a single common ancestor in the distant past and all living things are related to one another. In much the same way that we might draw a family tree of our own ancestors, scientists can draw a Tree of Life to show how all living things are related. Evolution refers to the change in traits of a population over successive generations. These traits are heritable!!!! en.wikipedia.org/wiki/Image:Phylogenetic_tree.svg

Evolution as Theory and Fact Confusion sometimes arises as to whether Evolution is a theory or a fact. Actually it is both! The theory of Evolution deals with how Evolution happens. Our understanding of this process is always changing. Evolution is also a fact as there is a huge amount of indisputable evidence for its occurrence. Presenter notes: There is often considerable confusion as to whether the concept of evolution is a theory or a fact. Actually it is both! Evolutionary theory deals with how evolution happens. This is an area of active research and new insights are constantly emerging to explain how one species gives rise to another. However, Evolution is also a fact because there is a great deal of indisputable evidence, as we will see in this talk, in support of its occurrence. What is uncertain is exactly HOW it happens, NOT whether it has happened at all.   Further background reading: Stephen Jay Gould, "Evolution as Fact and Theory," Discover 2 (May 1981): 34-37; available here: http://www.stephenjaygould.org/library/gould_fact-and-theory.html Rodin’s “The Thinker”

Talk Outline Part 1: How was evolution discovered? Part 2: How does evolution work? Practical: Natural Selection in the Peppered Moth Presenter notes: This talk has three parts. In the first part we will look at the scientific breakthroughs that led to the discovery of evolution between 1800 and 1940 and consider some of the objections to evolution raised by some fundamentalist religious groups. In the discussion that follows we will debate a controversial issue that is often raised by fundamentalist Christians in the USA - whether Creationism and Evolution should be given “equal time” in science lessons. In the second part, we will think about how Evolution works, and consider how one species can give rise to another. In the Practical we will then consider an example of Evolution in action as we turn our attention to the case of the Peppered Moth. Finally, and most importantly, we will address the evidence for Evolution and show why Biology simply does not make sense without it.

Early Thinking: Fixed species Michelangelo’s fresco on the ceiling of the Sistine Chapel Presenter notes: So let’s start by thinking about the discovery of Evolution. In Greek writing there is evidence of concepts associated with evolution. Many of the myths that were popular during this time were about evolution and creation concepts. Beginning in Classical times and persisting until long after the Renaissance, scientists thought species were fixed and unchangeable (or ‘immutable’ to use the language of the era). Their reasoning ran something like this: if God’s creation was perfect from the start, why would He bother to tinker with it at a later date? en.wikipedia.org/wiki/The_Creation_of_Adam From Classical times until long after the Renaissance, species were considered to be ______________________.

1500’s-1700’s 1500’s 1600’s - ____________________________, 1700’s Early philosophers ___________about nature of life. 1600’s - ____________________________, thus leading to new scientific disciplines. 1700’s Carolus Linnaeus Developed a system for naming and organizing organisms (taxonomy) In the 1500’s the microscope was invented. This allowed for scienctists to see cells for the first time. The science of emryology was born. During the 1600’s philosophers wrote about the naature of sciecne. They wanted to know wheter or not life arose from water, how organisms were classified, and the relationship of the natural world to theories of origin. In the 1700’s Carolus Linnaeus developed a system of classifying and naming organisms. This filed is now called taxonomy. Many of his classifications were controversial at the time.

1800’s- 2000’s Early 1800’s Mid to late 1800’s 1900’s- 2000’s _________________theory becomes known Mid to late 1800’s ___________________write papers on evolution Darwin publishes _________________________ ___________________develops basics of heredity 1900’s- 2000’s Discovery of gene and continued research

Lamark: Selective Use or Disuse Around 1800, scientists began to wonder whether species could change. Lamarck proposed: _________________________________________________________________________________________________________________________________________ Hence giraffes got their long necks through generations of straining to reach high branches. _____________________________! Presenter notes: However, around 1800, some scientists began to wonder if species could change their form or ‘transmute’. One of the early proponents of this idea was French scientist, Jean Baptiste de Lamarck (1744-1829). If species were able to change their form over time, then how did it happen? Lamarck thought that if an animal acquired a characteristic during its lifetime, it could pass it onto its offspring. One of his favorite examples was the giraffe. In his view, the giraffe got its long neck through straining to reach the leaves on high branches, and this characteristic got passed down the generations. Most scientists of his day thought that Lamarck was wrong. At that time, only a few radical thinkers like Charles Darwin’s grandfather, Erasmus, agreed that species could change over time. Jean Baptiste de Lamarck

Fossils and Strata http://en.wikipedia.org/wiki/ ImageWilliam_Smith.g.jpg http://en.wikipedia.org/wiki/Image: Geological_map_of_Great_Britain.jpg http://en.wikipedia.org/wiki/Image:Smith_fossils2.jpg Presenter notes: About the same time that these radical thinkers were discussing the transmutation (or evolution) of species, geologists like William Smith were beginning to map the rocks and fossils of Britain. Smith and others were able to show that rocks were laid down in a certain order and that the different fossils in different layers lived at different intervals of geological time. Here was clear evidence that different species had existed in the past compared with today. However, Smith did not go on to ask the question, ‘Why?’ or to consider that this might be evidence for evolution. William Smith, his geology map & some of his fossil specimens At about the same time, geologists like William Smith were mapping the rocks and fossils of Britain. He and others showed that ______________________________compared with today.

Darwin’s Voyage From 1831-1836, a young naturalist called ___________________ ____________ in HMS Beagle. He was dazzled by the amazing diversity of life and started to wonder how it might have originated Presenter notes: In the early nineteenth century, Charles Darwin (1809-1882) rekindled ideas about evolution. In a sense, Evolution was in Darwin’s blood because, as we’ve already noted, his grandfather was an early supporter of the concept. From 1831-1836, Darwin toured the world on HMS Beagle as a young naturalist. He was dazzled by the amazing diversity of life, including some amazing fossils such as rodents the size of hippopotamuses and started to wonder how it might have originated. Voyage of the Beagle en.wikipedia.org/wiki/Image:Charles_Darwin_by_G._Richmond.jpg en.wikipedia.org/wiki/Image:HMS_Beagle_by_Conrad_Martens.jpg

Who Shaped Darwin’s Thinking? ________________ An English Economist who in 1798 he ______________________________________________________. Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone. Malthus was an English Economist. In 1798, he observed that babies were being born faster than people were dying. He reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone. Malthus proposed that war, famine and disease limited the growth of human populations. Darwin realized that this reasoning applied even more to plants and animals. Humans produce fewer offspring than most other species.

Who Shaped Darwin’s Thinking? Geologists: Hutton and Lyell Fundamentalists said that the earth was around 6000 years old Hutton and Lyell argued that the ________________of years old because…. layers of rock ___________________ processes such as volcanoes and earthquakes shaped the earth and still occur today Fundamentalists said that the earth was around 6000 years old Hutton and Lyell argued that the earth is many millions of years old b/c layers of rock take time to form processes such as volcanoes and earthquakes shaped the earth and still occur today Hutton and Lyell helped scientist recognize that Earth is many millions of years old and the processes that changed Earth in the past are the same processes that operate in the present. Basically, the Earth is very old and it has changed over time. 1795-geologist James Hutton proposed that layers of rock form very slowly and they are pushed up by forces beneath the Earth’s surface. Other rocks are buried and still others are pushed up from the sea floor to form mountain ranges. These resulting features are then shaped by natural forces such as rain, heat, and cold. These processes are extremely slow and therefore, he proposed, the Earth is not only a few thousand years old but millions. Charles Lyell wrote Principles of Geology in 1833. In it he stressed that scientists must explain past events in terms of processes that they can actually observe. For example, a volcano erupts lava and gases to form land, an earthquake can change a landscape as well as erosion. This happened millions of years ago as well as the present. His work explained how awesome geological features could be built up or torn down over long periods of time. Darwin had experienced these geologic phenomena. He wrote about an earthquake in which the rocks on a shoreline were moved 3 meters above where it originally was.

The Galapagos Islands _______________________________. Noted that each island had its own type of tortoises and birds that were clearly different from other islands

Survival of the Fittest In his Origin of Species, published in 1859, Darwin __________________________________________________________. Where food was limited, _____________________________ ______________________________. This would lead to the _______________ of the best adapted individuals and eventually the ________of a new species. Natural Selection explains adaption Presenter notes: On his return from the Beagle the jigsaw pieces started to fit together in his mind. Around 1842 Darwin read an essay about human population growth by Malthus. Malthus had argued that human population would grow more quickly than food supply. Consequently competition for food would become intense and only the fittest and most able would survive. Darwin applied these ideas to all of life and came up with his now famous concept of Natural Selection. Darwin reasoned that if an organism possessed a character that improved its chances of survival, then it would be more likely to pass on that character to the next generation. Therefore organisms would become progressively adapted to their environment, leading to the evolution of new species. Darwin published this idea in his “Origin of Species by means of Natural Selection” in 1859. Darwin in 1860 en.wikipedia.org/wiki/Image:Darwin%27s_finches.jpeg

4 Principles of Natural Selection 1. ___________________________________ Physical traits vary. Some can be inherited

4 Principles of Natural Selection 2. __________________________________ Food, shelter, territory, mates and water are limited resources. You must compete to have enough to live.

4 Principles of Natural Selection 3. ____________________________________ Offspring are lost to disease, predators, and other factors. Not all can survive.

4 Principles of Natural Selection 4. ___________________________________ _______________________________________ Organisms with new adaptations survive, mate, and may pass on new genes to their offspring