SCIENCE Science refers to a system of acquiring knowledge. This system uses observation and experimentation to describe and explain natural phenomena. 1

LAW generalizes a body of observations A law describes a pattern or an event in nature that is always true. 2

FACT an observation that has been confirmed repeatedly and is accepted as true “You’re entitled to your own opinions. You’re not entitled to your own facts.” 3

THEORY a well substantiated explanation of some aspect of the natural world backed up by evidence such as; confirmed observations (facts), laws, and successfully verified hypotheses A scientific theory might explain how and why an event occurs. 4

EVOLUTION Change over time Biological evolution, simply put, is descent with modification. Small-scale evolution (changes in gene frequency in a population from one generation to the next) Large-scale evolution (the descent of different species from a common ancestor over many generations). 5

Q: WHY IS IT CALLED THE THEORY OF EVOLUTION? 1.It has been thoroughly tested many times by many people and has gained widespread acceptance. 2.It has not yet been proven well enough to satisfy most people.

SURVEY RESULTS DATA 1.How many survey participants were students? 2.How many were adults? 3.How many work in a science-related field? 4.How many people gave an accurate definition of science? 5.How many said they liked science? 6.How many had misconceptions about what a theory, a fact, or a law is (as used in the scientific community)? 7.How many people gave a scientific definition of evolution?

8 The Evidence for Evolution

FOSSIL EVIDENCE OF EVOLUTION Fossil records document the course of life through time 9

FOSSIL EVIDENCE OF EVOLUTION Fossils document evolutionary transition The oldest known bird fossil is the Archaeopteryx It is intermediate between bird and dinosaur Possesses some ancestral traits and some traits of present day birds Archaeopteryx was first found in

FOSSIL EVIDENCE OF EVOLUTION Fossil of Archaeopteryx 11

FOSSIL EVIDENCE OF EVOLUTION Recent discoveries Four-legged aquatic mammal Important link in the evolution of whales and dolphins from land- dwelling, hoofed ancestors Tiktaalik: a species that bridged the gap between fish and the first amphibian 12

FOSSIL EVIDENCE OF EVOLUTION Whale “missing links” 13

FOSSIL EVIDENCE OF EVOLUTION Evolutionary change in body size and toe reduction of horses 14

ANATOMICAL EVIDENCE FOR EVOLUTION Homologous structures : structures with different appearances and functions that all derived from the same body part in a common ancestor The bones in the forelimb of mammals are homologous structures Different functions, same ancestor structure 15

ANATOMICAL EVIDENCE FOR EVOLUTION Homology of the bones of the forelimb of mammals 16

ANATOMICAL EVIDENCE FOR EVOLUTION Strongest anatomical evidence supporting evolution comes from comparisons of how organisms develop. Early vertebrate embryos possess pharyngeal pouches that develop into: In humans: glands and ducts In fish: gill slits 17

Developmental similarities reflect descent from a common ancestor 18 Anatomical Evidence for Evolution

ANATOMICAL EVIDENCE FOR EVOLUTION Vestigial structures: have no apparent function, but resemble structures their ancestors possessed 19 Vestigial structures of a whale

ANATOMICAL EVIDENCE FOR EVOLUTION Humans Muscles for wiggling ears Boa constrictors Hip bones and rudimentary hind legs Manatees Fingernails on their fins Blind cave fish Nonfunctional eyes 20

EVOLUTION EVIDENCE: MOLECULAR BIOLOGY Similarities in DNA, proteins, genes, and gene products Common genetic code

Why should different organism possess related genes? Why does the degree of relationship of genes match their degree of relationship established by other methods?