Evidence for Evolution

Theory vs. Law

• Laws can be seen and studied directly.• Theories can’t be seen or studied directly

because they are either too big, too small, or too far removed in time.

Two Types of Evolution

Microevolution—on a small scale, creating changes in a population like we will see in Gizmos

Macroevolution—on a big scale, forming totally new types of organisms

Evidence for EvolutionMain areas of evidence include:

Biological

•Anatomy

•Physiology

•Embryology

Molecular Biology (Genetics)

Paleontology (Fossils)

Fossil RecordEvidence of past life shows even more variety.

Some extinct forms show characteristics that are in-between major groups.

The more we find, the more that gaps are filled in.

Distribution of Related Species

100 species of marsupials in Australia but no placental mammals (dog, cat, horse, bear)

New Zealand and Hawaii have unique plants and animals.

PhysiologyHow tissues and organs work in the body

Vestigial organs—organs or structures that are “left over” in an imperfect form (they don’t do any good any more)

Wings on flightless birds Erector pili and body hair

Vestigial organs, cont.

Human tailbone (coccyx)

Eyes on blind fish living in caves

Wisdom teeth

Vestigial organs, cont.Human appendix

300,000 appendectomies in 2000 and 371 deaths from appendicitis

AnatomyHomologous structures—similar structures with different uses

Embryology

How an organism develops

Organisms go through some (not all) of the stages that their ancestors went through

Molecular Biology Genetics

Especially now that we have completed the genome of many organisms, we can see just how close the DNA is.

Genes from one animal can be put into another and they work just fine.

They are the same gene.http://www.pbs.org/wgbh/evolution/library/03/4/l_034_04.html