Transcript
Page 2: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Evidence of Evolution

1. Fossil Record2. Homologous Body structures

3. Similarities in Embryology 4. Biochemical Evidence

Page 3: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Evidence of Evolution:The Fossil Record

• Fossil record provides evidence that living things have evolved

• Fossils show the history of life on earth and how different groups of organisms have changed over time

Page 4: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Relative vs. Absolute Dating

Page 5: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Relative Dating

• Can determine a fossil’s relative age

• Performed by estimating fossil age compared with that of other fossils

• Drawbacks – provides no info about age in years

Page 6: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Absolute Dating

• Can determine the absolute age in numbers

• Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain

• Drawbacks - part of the fossil is destroyed during the test

Page 7: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

– A half-life is the amount of time it takes for half of the isotope to decay.

• Radiometric dating uses decay of unstable isotopes.

– Isotopes are atoms of an element that differ in their number of neutrons.

Page 8: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Primate Fossils

Australopithecus Homo erectus Homo sapien

Page 9: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Primate Bone Structure

Page 10: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Evidence of Evolution:Homologous Body Structures

– Structures that have different mature forms but develop from the same embryonic tissues

Ex: Wing of bat, human arm, leg of turtle

Turtle

Alligator

Bird

Page 11: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Evidence of Evolution:Homologous Structures

• Features that are similar in structure but appear in different organisms and have different functions.

• Strong evidence for common ancestor.• Ex: forelimbs of humans, bats and moles.

Human hand Bat wingMole foot

Page 12: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Analogous Structures• Structures that perform a similar

function.• Not evidence of common ancestry.

Page 13: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Vestigial Structures• Remnants of organs or structures that had a

function in an early ancestor.• Ex: Ostrich wings, used for balance but not

flight• Ex: Humans’ appendix

Page 14: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Evidence of Evolution:Similarities in Embryology

In their early stages of development, chickens,

turtles and rats look similar, providing

evidence that they shared a common

ancestry.

Page 15: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Embryological Development

Page 16: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Evidence of Evolution:Biochemical Similarities

• Scientists study nucleotide sequences in DNA and proteins in different organisms to determine ancestry.

• If the organisms are closely related they will have similar sequences of nucleotides in their DNA and arrangement of amino acids in proteins.

Page 17: Evidence of Evolution. 1.Fossil Record 2.Homologous Body structures 3.Similarities in Embryology 4.Biochemical Evidence

Evidence of Evolution:Biochemical Similarities

Organism Amino Acid Differences

Organism Amino Acid Differences

Human beta chain 0 Mouse 27

Gorilla 1 Kangaroo 38

Rhesus monkey 8 Chicken 45

Dog 15 Frog 67

Cow 25 Soy bean 124

The more similar the amino acid sequence, the more closely related the organisms are.


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