Evidence of evolution
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Evidence of Evolution. Evidence of Evolution. Fossil Record Homologous Body structures Similarities in Embryology Biochemical Evidence. Evidence of Evolution: The Fossil Record. Fossil record provides evidence that living things have evolved

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Evidence of Evolution

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Evidence of Evolution


Evidence of Evolution

  • Fossil Record

  • Homologous Body structures

  • Similarities in Embryology

  • 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


Relative vs. Absolute Dating


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


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


  • Radiometric dating uses decay of unstable isotopes.

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

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


Primate Fossils

AustralopithecusHomo erectusHomo sapien


Primate Bone Structure


Evidence of Evolution:Homologous Body Structures

Turtle

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

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

Alligator

Bird


Molefoot

Batwing

Human hand

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.


Analogous Structures

  • Structures that perform a similar function.

    • Not evidence of common ancestry.


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


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.


Embryological Development


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.


Evidence of Evolution:Biochemical Similarities

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


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