Evidence for Evolution

Bill Nye: http://www.youtube.com/watch?v=svHQ4BQY__o&feature=results_video&playnext=1&list=PL51E21E1D19FB81E0

Major Evidence for Evolution Fossil record Homologous structures Vestigial structures Biochemical evidence Embryological development

Charles Darwin 1859 – “Origin of Species”

published1. Argued from evidence that species

inhabiting Earth today descended from ancestral species

2. Proposed a mechanism for evolution Natural Selection

Many scientists helped pave the way for Darwin’s Theory

Theory of Evolution By Natural Selection In each generation of a species,

individuals have slight differences.

Sometimes these variations make an individual more successful in its environment

(more food, live longer, reproduce more, attract better mates). Then individual may then reproduce and pass this variation on to its offspring.

Then the individual may reproduce and pass this variation on to its offspring.

Natural Selection

Variations in individuals are controlled by genes.

Individuals have no control over what variations they will have.

Useful variations are NOT ALWAYS passed on.

Variations that are not useful may also be passed on.

Alfred Russel Wallace co-discovered natural selection and prompted

Darwin to finally rush his Origin of Species to press.

One of the modern world’s greatest scientific adventurer explorers

eight-year exploration of Southeast Asia and the Malay Archipelago he wrote The Malay Archipelago in 1869,

Geographical Distribution of Animals (1876) is one of the seminal works in the field.

the workhorse of Darwinian evolution, diverged from Darwin’s methodological naturalism (i.e., the notion that scientists must invoke only natural processes functioning via unbroken natural laws in nonteleological ways) to propose a theory of evolution defined by intelligence and design.

Jean Lamarck

1. Fossil Record What does the Fossil Record tell

us about organisms? Looks (size, shape, etc.) Where or how they lived What other organisms they lived

with

What time period they lived in (based on location in rock layers)

What order living things came in (based on location in rock layers)

Transitional formsOrganisms that were

intermediate (between) two other major organisms

Example: Horse

Homologous Structures-bodily structures that are similar in structure, but different in function, due to sharing a common ancestor

2. Homologous Structures

Homologous Structures

Analogous Structures Analogous structures- bodily

structures that are similar in function, but not in structure. NOT EVIDENCE OF COMMON ANCESTRY. Example: wings of a bee and

wings of a bird

3. Vestigial Structures Structures that serve no function

but useful structures in earlier ancestors Examples: Ear muscles Human tailbone Appendix

Vestigial Organs

4. Embryological Development Embryo- fertilized egg that will/is in the

process of growing into a new individual

Closely related organisms go through similar developmental stages early in development All vertebrates have gill pouches sometime

during their early development

5. Molecular/Biochemical Evidenceo DNA used to translate

nucleotide sequences into amino acid is essentially the same in all organisms

o Proteins in all organisms are composed of the same set of 20 amino acids

o Powerful argument in favor of the common descent of the most diverse organisms.

Universal Code

Biochemical Compound Ex DNA Cyt C 20 amino acids Some enzymes

Molecular/Biochemical Evidence Cytochrome c

An ancient protein common to all aerobic (oxygen breathing) organisms

Amino acid sequence to make cytochrome c differs increasingly the more distantly related two organisms are (very similar amino acid sequence = closely related)

The cytochrome c of humans and chimpanzees is identical

DNA

Cyt C