Thought Question What evidence did the scientist in Great Transformations find that indicated whales evolved from land animals?

Theory vs. Law Law = statement about a repeatable event Theory = explanation of a natural phenomena based on extensive evidence Both are considered factual understandings of the natural world. One cannot become the other, they exist independently of each other and serve different purposes.

The Three Foundational Theories of Biology Cell Theory Germ Theory Theory of Evolution

Cell Theory All living things are composed of cells Cells are the basic units of structure and function in living things New cells are produced from existing cells Areas of science that have contributed: Cell biology Microbiology Microscopy

Germ theory Infectious diseases are caused by microorganisms of different types, commonly called germs Areas of science that have contributed: Cell biology Microbiology Epidemiology Bacteriology Virology Pathology Parasitology

Theory of Evolution Evolution: changes in gene frequencies in a population over time or “descent with modification” Explanation for diversity of life on Earth Species alive today are descended with modification from ancestral species. This process of changes from common ancestors unites all organisms on Earth.

History of Evolutionary Theories 1800s Europe: Dominant belief was that Earth and all its forms of life had been created a few thousand years ago and since then neither the planet nor its living species had changed

History of Evolutionary Theories James Hutton, 1795 Geologist WHAT: Published hypothesis about the layers of rock, formation of mountains, erosion, etc that occurs over millions of years WHY: Could no longer measure the history of the planet in terms of human lifetimes

History of Evolutionary Theories Jean-Baptiste Lamarck, 1809 French naturalist WHAT: Species changed through acquired characteristics Example: if you lift weights, your children will have big muscles Incorrect, but did begin to explain adaptation WHY: Idea that species change

History of Evolutionary Theories Charles Lyell, 1833 Geologist WHAT: Argued that the formation of Earth took place through small changes over a long period of time (old Earth) WHY: Darwin expanded this to species changing over time

History of Evolutionary Theories Darwin, set sail on Beagle 1831 WHAT: Realized organisms were not fixed and unchangeable (based on fossil record and biodiversity) WHY: Provided explanation of the process of evolutionary change (theory of evolution by natural selection)

History of Evolutionary Theories Thomas Malthus, 1798 WHAT: If human population continued to grow, resources would run out WHY: Darwin applied this struggle for resources to plants and animals an oyster produces millions of eggs in one year, a maple tree produces thousands of seeds in a single summer they don’t all go on to live, why do some die?

History of Evolutionary Theories Alfred Russell Wallace, 1858 Naturalist WHAT: Independently thought of idea of natural selection WHY: Ultimately lead to Darwin publishing On the Origin of Species in 1859