Thought QuestionWhat 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 TheoryAll living things are composed of cellsCells are the basic units of structure and function in living thingsNew cells are produced from existing cells

Areas of science that have contributed:Cell biologyMicrobiologyMicroscopy

Germ theoryInfectious diseases are caused by microorganisms of different types, commonly called germs

Areas of science that have contributed:Cell biologyMicrobiologyEpidemiologyBacteriologyVirologyPathologyParasitology

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, 1795GeologistWHAT: 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

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

History of Evolutionary Theories

Charles Lyell, 1833Geologist

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 TheoriesDarwin, set sail on Beagle 1831WHAT: 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, 1798WHAT: 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