- explain how living things are able to change over time - assess the many types of evidence that support the theory of evolution - describe the contributions of Charles Darwin and other scientists - explain and model the process of natural selection - provide examples of how modern advances in science have enriched and supported our understanding of evolution - outline the timing of major events in the history of life on Earth
What Is a Scientific Theory?
The word "theory" has two common meanings—an everyday meaning and a scientific one. In everyday language, "theory" is often used to mean "an educated guess" or one of many possible explanations about some phenomenon. When someone says "I have a theory . . .” they usually mean that they are unsure but think they might know how to account for some observation. In science, such tentative explanations are called hypotheses. A scientific theory is much more than an educated guess. A scientific theory is an explanatory model that accounts for a very large body of evidence. Scientific theories provide a basis for explaining observations of the natural world and for making testable predictions.
You are already familiar with two powerful scientific theories: cell theory and atomic theory, and you have no doubt heard of the theory of gravity. These theories attempt to explain our observations of the universe around us: the organization of living things, the organization of matter, and the main force that both holds you down on Earth's surface and governs the motions of bodies in our solar system and beyond. Unlike tentative guesses, a scientific theory is founded on a large body of evidence that gives scientists great confidence in the theory. That does not mean that these theories are complete or perfectly accurate. All scientific theories are considered tentative and open for revision and refinement as new evidence is gathered. However, scientists would be shocked to find an animal without DNA, an atom without electrons, or an apple that "fell up."
Once established, scientific theories are of great practical value. They allow us to make accurate and precise predictions, enabling us to perform tasks as complex as DNA fingerprinting and landing spacecraft on the surface of Mars.
As you will learn in this chapter, the theory of evolution is a scientific theory based on a large body of evidence that can be used to explain the history of life on Earth. It allows scientists to make accurate and useful predictions. The evidence includes fossils of ancient life forms, genetic analysis, comparative anatomy, and the distribution of living things on Earth.
STARTING POINTS
Answer the following questions using your current knowledge. You will have a chance to revisit these questions later, applying concepts and skills from the chapter.
1. The cell theory and the atomic theory were not always widely accepted. Do you accept these scientific theories as valid? If so, why? If not, why not?
2. Scientists gain confidence in their theories when they have more than one kind of supporting evidence. Why do you think this is so? Can you think of other situations in which more than one type of evidence is used to support a theory or prediction?
3. Evolutionary biologists, and most children, are fascinated by dinosaurs. In what way do you think fossils of dinosaurs might provide evidence of evolution?
4. Mutations can result in heritable changes in the phenotype of an individual. What do you think the long-term effects would be if many mutations accumulated over time?
KEY CONCEPTS
After completing this chapter you will be able to
- explain how living things are able to change over time
- assess the many types of evidence that support the theory of evolution
- describe the contributions of Charles Darwin and other scientists
- explain and model the process of natural selection
- provide examples of how modern advances in science have enriched and supported our understanding of evolution
- outline the timing of major events in the history of life on Earth
What Is a Scientific Theory?
The word "theory" has two common meanings—an everyday meaning and a scientific one. In everyday language, "theory" is often used to mean "an educated guess" or one of many possible explanations about some phenomenon. When someone says "I have a theory . . .” they usually mean that they are unsure but think they might know how to account for some observation.
In science, such tentative explanations are called hypotheses. A scientific theory is much more than an educated guess. A scientific theory is an explanatory model that accounts for a very large body of evidence. Scientific theories provide a basis for explaining observations of the natural world and for making testable predictions.
You are already familiar with two powerful scientific theories: cell theory and atomic theory, and you have no doubt heard of the theory of gravity. These theories attempt to explain our observations of the universe around us: the organization of living things, the organization of matter, and the main force that both holds you down on Earth's surface and governs the motions of bodies in our solar system and beyond. Unlike tentative guesses, a scientific theory is founded on a large body of evidence that gives scientists great confidence in the theory. That does not mean that these theories are complete or perfectly accurate. All scientific theories are considered tentative and open for revision and refinement as new evidence is gathered. However, scientists would be shocked to find an animal without DNA, an atom without electrons, or an apple that "fell up."
Once established, scientific theories are of great practical value. They allow us to make accurate and precise predictions, enabling us to perform tasks as complex as DNA fingerprinting and landing spacecraft on the surface of Mars.
As you will learn in this chapter, the theory of evolution is a scientific theory based on a large body of evidence that can be used to explain the history of life on Earth. It allows scientists to make accurate and useful predictions. The evidence includes fossils of ancient life forms, genetic analysis, comparative anatomy, and the distribution of living things on Earth.
STARTING POINTS
Answer the following questions using your current knowledge. You will have a chance to revisit these questions later, applying concepts and skills from the chapter.
1. The cell theory and the atomic theory were not always widely accepted. Do you accept these scientific theories as valid? If so, why? If not, why not?
2. Scientists gain confidence in their theories when they have more than one kind of supporting evidence. Why do you think this is so? Can you think of other situations in which more than one type of evidence is used to support a theory or prediction?
3. Evolutionary biologists, and most children, are fascinated by dinosaurs. In what way do you think fossils of dinosaurs might provide evidence of evolution?
4. Mutations can result in heritable changes in the phenotype of an individual. What do you think the long-term effects would be if many mutations accumulated over time?
October 27th, 2017
7.1 Biological Change Over Time
October 30th, 2017
7.2 The Evolution of an Idea
October 31st, 2017
7.3 Biology JOURNAL: Voyage of the HMS Beagle - ASSIGNMENT due Tuesday, Nov 7th, 2017
November 1st, 2017
7.4 The Evidence for Evolution
November 2nd, 2017
7.5 On the Origin of Species
November 6th, 2017
7.6 The Modern Theory of Evolution
Chapter 7 Self Quiz and Chapter 7 Review - due Wednesday, Nov 8th, 2017
Chapter 7 Quiz (Thursday, November 9th, 2017)