What is science? • Evolution: a quick overview • -- evidence • -- mechanisms • The age of the Earth/”how do you know how old it is?” • What is creationism • Evolution answers questions • 7. Why is evolution important? www.priweb.org/dev/volunteer
Science = -- a “Way of knowing” -- materialistic/naturalistic -- hypotheses that are testable and provisional
Science -- certainty -- ethics -- values -- religion -- politics -- the answer for every question -- all of human thought
Organic EvolutionDefinitions: The hypothesis that all organisms on Earth are connected by bonds of genealogy and have changed through time.Darwin: “descent with modification”
The Origin tried to do 2 things: • 1) Convince the reader that evolution has occurred and is an adequate explanation for observations about life. • 2) Convince the reader that a particular mechanism – natural selection – is the main cause of evolution.
Theoccurrence of evolution (“the fact of evolution”) …mechanism by which evolution occurs.
Evolution is scientifically useful. • it is testable • it answers questions • it stimulates further research
“How did organisms come to be the way they are?” • They have a history. • They don’t. They were created as we see them. • We can extrapolate from changes we observe today. • We cannot extrapolate from changes we observe today.
Evidence for Evolution • 1) Biogeography • 2) Fossil record • 3) Classification • 4) Comparative Anatomy • 5) Observed small-scale changes • 6) Genetics
Evidence for Evolution: Biogeography Toucan (Neotropics) Hornbill (SE Asia)
Evidence for Evolution: The fossil record Archaeopteryx and modern pigeon Archaeopteryx Compsognathus
Evidence for Evolution: Comparative Anatomy North Atlantic Right Whale
No serious practicing geologist or organismal biologist has seriously questioned whether evolution has occurred, or whether it is an adequate explanation for the history and diversity of life since at least the 1890s. There has been, and continues to be, debate about the causes and mechanisms of evolutionary change.
Mechanisms of Evolution • Directed evolution/Internal mechanisms - “orthogenesis” etc. • Inheritance of acquired characteristics (“Lamarckism”) • Genetic drift • Neutral theory • Natural Selection • Higher level sorting
Natural SelectionDefinition: The non-random and differential reproduction of different genotypes acting to preserve favorable variants and eliminate less favorable variants.
“3 unarguable observations and 2 inescapable conclusions” • Observations: • 1) There is variation • 2) At least some of it is inherited • 3) There is vast overproduction • Conclusions: • 1) There is a “struggle for existence”. • 2) On average, those individual organisms with traits that confer some advantage in this struggle will leave more offspring.
The age of the Earth • aka: “how do you know how old it is?” • aka: “aren’t there problems with ‘carbon dating’?”
Techniques for dating things • Relative dating: “X is older than Y” • Numerical dating: “X is Y years old” • Historically unique events: e.g., 1965 Mustang • Processes of change (observe results): e.g., weathering, deterioration, erosion • Processes of change (experiments): e.g., moldy cheese • Historically repeating events: e.g., Greek revival architecture
Radiometric Dating: the basic idea • A product is detectable • The rate of production of that product is known • Product amount is 0 (or known) at age 0 of sample • Product / Rate = Time • example: 10g / 0.5g/yr = 20 years
Seneca Stone Quarry http://www.earth.rochester.edu/ees207/Eastern_Transect/senecastone.html
Bentonites (ancient volcanic ash layers) in the Seneca Stone Quarry http://www.earth.rochester.edu/ees207/Eastern_Transect/senecastone.html
What is science? • Evolution: a quick overview • -- evidence • -- mechanisms • The age of the Earth/”how do you know how old it is?” • What is creationism • Evolution answers questions • 7. Why is evolution important?
“Creationism” isn’t science
Creationism: a definition • General: The Universe, the Earth, and all life were created directly by a supernatural creator (God). • Variations: • young Earth vs. old Earth • one creation (“special”) vs. many (“sequential”) • non-humans vs. humans
Creationism: a taxonomy • Scientific creationism (no reliance on Biblical revelation, utilizing only scientific data) • Biblical creationism (no reliance on scientific data, using only the Bible) • Scientific Biblical creationism (full reliance on Bible, but also using science) (from Scott, Evolution vs. Creationism, 2004)
Creationism and science • It was cutting-edge science… about 500 years ago. • It has been tested, and it failed. • Current public opinion, however…
U.S. public opinion, 2005 HALF OF AMERICANS ARE “CREATIONISTS” • 54% do not think human beings developed from earlier species (up from 46 percent in 1994) • 49% believe plants and animals have evolved from some other species; 45% do not believe that. • 46% believe apes and humans have a common ancestry; 47% believe we do not. • 46% agree that "Darwin’s theory of evolution is proven by fossil discoveries“; 48% disagree. Source: Harris poll, June 2005
Poll by the Pew Forum on Religion & Public Life, conducted July 2005 among 2,000 U.S. adults • Life has existed in its present form since the beginning of time: 42% • Life has evolved over time: 48% • Guided by a supreme being: 18% • Evolution by natural selection: 26% • Don’t know how evolved: 4% • Don’t know: 10%
Polls 2001 BUT • “Evolution should be taught in the public schools” (70%) • “The continents on which we live have been moving their location for millions of years...”. (79%)
Intelligent Design: what is it? • Holds that “where there is a watch, there must be a watchmaker”. • Living things are too complex not to have been designed by an intelligent designer. • Claims to accept evolution and an old Earth.
Intelligent Design:How to answer a question about it • Even if it doesn’t mention God, religion, or a “creator”, it assumes there is/was one. • This is supernatural and non-testable. • It’s not science.
Why does this matter? • Science • Science education