Evidence of evolution
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Evidence of Evolution. Comparative Anatomy. Comparative Anatomy. Comparative anatomy includes vestigial structures, skeletal structures, DNA, and embryology.

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Evidence of Evolution

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Evidence of evolution

Evidence of Evolution

Comparative Anatomy


Comparative anatomy

Comparative Anatomy

  • Comparative anatomy includes vestigial structures, skeletal structures, DNA, and embryology.

  • Comparisons of anatomical features in different organisms often provide evidence of change over time, as organisms are often classified together according to similarities in their structures.

  • It was through comparing the anatomy of organisms that scientist discovered phylogeny, meaning the evolutionary history of a group of organisms.


Vestigial structures

Vestigial Structures

  • Vestigial structures provide evidence of change.

  • Vestigial structures have no function in one species but may continue to function in another.

  • These organs are usually dwarfed.

  • Sometimes vestigial organs may be adapted for new uses

  • Even though organisms have these organs there is no significant disadvantage to the organism.

  • Examples of these include:

    • The human appendix which is useless in humans, but in other mammals it is necessary for digestion of high cellulose diet.

    • The human external ear muscles.

    • The tail bone.

    • Wisdom teeth.

    • Some snakes have skeletal limbs.

    • Hind limb structures embedded deep in their bodies

    • Penguin wings that cannot be used for flying but are adapted for swimming


Skeletal structures

Skeletal Structures

  • Skeletal structures, also known as homologous structures, are structures that share a common origin but may serve different functions in modern species.

  • These structures are evidence that organisms with similar structure evolved from a common ancestor.

  • Examples include the forelimbs of a variety of mammals. For example, human, cat, whale and bat.

  • These species show the same skeletal elements, as in the humerus, radius and ulna.

  • However these skeletal elements have been modified over time to suit the different functions suitable for the type of mammal.


Skeletal comparison

Skeletal Comparison


Evidence of evolution

DNA

  • Scientists hypothesize that if all organisms living today evolved from a common ancestor, they should have similar genetic material.

  • Species appearing to be close relatives should have greater similarities in their chromosomes and DNA than species appearing to be distant relatives.


Embryology

Embryology

  • Embryology of organisms can be used to demonstrate the existence and even degree of relatedness of organisms.

  • In the early stages of development embryos of many organisms look extremely similar.

  • Embryos in mammals, birds, reptiles and fish have many body similarities in common e.g. Gill slits, two chambered heart, and tail.

  • As the embryos develop further, the similarities gradually disappear.

  • This embryonic resemblances indicate that organisms are related by their common ancestors.


Embryonic comparisons

Embryonic Comparisons


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