The history of taxonomy
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The History of Taxonomy. Emily Javore. Taxonomy. Taxis : order or arrangement. Nomos : law or science. The practice and science of classification. More specifically, the classification of organisms. Emperor Shen Nung 2650 BC.

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The History of Taxonomy

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The history of taxonomy

The History of Taxonomy

Emily Javore


Taxonomy

Taxonomy

  • Taxis: order or arrangement.

  • Nomos: law or science.

  • The practice and science of classification.

  • More specifically, the classification of organisms.


Emperor shen nung 2650 bc

Emperor ShenNung2650 BC

  • The earliest known classification was in 2650 BC by Emperor ShenNung. He is known as the Father of Agriculture and Medicine in China.

  • Most early classifications began as lists of medical plants.


Early classifications

Early Classifications

  • The first classification systems often broke plants down into three groups: trees, shrubs and herbs.

  • Eber’s medical papyrus (Egypt 1500 BC) classified plants based on their habitats.


Aristotle 384 bc 322 bc

Aristotle384 BC – 322 BC

HistoriaAnimalium

Animals with blood –

Live-bearing (humans and mammals)

Egg-bearing (birds and fish)

Animals without blood –

Insects

Shelled and non-shelled crustaceans

Mollusks


Aristotle 384 bc 322 bc1

Aristotle384 BC – 322 BC

  • The Great Chain of Being (Ladder of Life)

    Aristotle believed that creatures were arranged in a graded scale of perfection rising from plants on up to man.

     He believed that species were fixed and unchanging, and this view persisted for the next two thousand years.


Great chain of being

Great Chain of Being


Theophrastus 372 287 bc

Theophrastus372-287 BC

  • A student of Aristotle’s.

  • “Father of Botany”

  • De HistoriaPlantarum (On Plants)

  • De CausisPlantarum(The Causes of Plants)

  • Classified over 500 plants

  • Annual, biennial, or perennial?


A new age

A New Age

  • Because of Aristotle’s profound influence, there was little innovation made within taxonomy until the 16th century.

    In the early 1500’s, voyages of expedition were taking place around the world (leading to the discovery of many new plants and animals that were before unknown).


The 16 th century

The 16th Century

  • With all of the new plants and animals that were being discovered, many scientists wanted a systematic way to name and classify them.

  • Many of the botanists were also physicians who were trying to find new medicines.


Andrea cesalpino 1519 1603

Andrea Cesalpino1519-1603

  • Italian physician

  • Created one of the first new systems of classification since Aristotle

  • De Plantis(On Plants)

  • Classification was based on the structure of the plant’s fruits and seeds, created what we now know as “genera”


Gaspard bauhin 1560 1620

GaspardBauhin1560-1620

  • Swiss physician

  • Described and named over 6,000 species of plants based on their “natural affinities”

  • His system was most likely the inspiration for binomial nomenclature, because he generally used only one descriptive word for each species


Confusion

Confusion

  • By the end of the 1600’s, multiple systems existed for the classification of plants.

  • Depending on which system of classification a scientist used, the same plant could have multiple names.

  • This was very confusing, especially when trying to use these plants for medicine.


Carolus linnaeus 1707 1778

Carolus Linnaeus1707-1778

  • Extremely influential Swedish botanist and physician

  • The father of modern taxonomy

  • The System of Nature 1735

  • Organized plants and animals from

    Kingdoms down to Species, basing this

    on their shared physical characteristics


Carolus linnaeus 1707 17781

Carolus Linnaeus1707-1778

  • Species Plantarum1753

  • Introduced Binomial Nomenclature (recognizing an organism by it’s genus and species).

    Ex: Homo sapiens

  • He also included a complete list of all plant genera and species known to him at the time


God created linnaeus named

“God Created, Linnaeus Named”

  • Up until the late 1800’s, Linnaean taxonomy persisted with minimal changes

  • The theory of the day was that “God created, Linnaeus named”

  • Until this point, organisms were categorized by their shared physical characteristics, and not by their evolutionary relationships


August wilhelm eichler 1839 1887

August Wilhelm Eichler1839-1887

  • German botanist

  • Divided plants into non-floral

    and floral plants

  • The first to use evolutionary

    relationships in taxonomy


Charles darwin 1809 1882

Charles Darwin (1809-1882)

The shift from traditional

taxonomy to cladistics first

occurred after evolution

and natural selection

were proposed by Charles

Darwin in The Origin of

Species. (1859)


Cladistics

Cladistics

  • The classification of species into groups which are based on their evolutionary relationships.

  • Monophyletic groups consist of an ancestor and ALL of its descendants.

  • Cladistics differs from the mechanisms of classification before it because it is based on derived characteristics.


Cladogram

Cladogram


Shared ancestry

Shared Ancestry

  • Cladistic taxonomy is based on shared characteristics that are inherited from a common ancestor . These characteristics include:

  • Anatomical structures

  • Patterns of embryonic development


The history of taxonomy

DNA

Since the birth of molecular biology, similarities between organisms can be compared at the protein and DNA level (making cladistic taxonomy more precise than ever).


Phylocode

Phylocode

  • The International Code of Phylogenetic Nomenclature

  • A movement to change the nomenclature away from the Linnaean system, to one where the evolutionary relationships between organisms are better represented.


Example

Example

  • Class: Mammalia

  • Current definition: The highest class of vertebrate. Warm-blooded. The young are nourished for a time by milk, or an analogous fluid, secreted by the mammary glands of the mother.

  • Possible Phylogenetic definition: the clade originating with the most recent common ancestor of Homo sapiens and Ornithorhynchusanatinus.


Phylocode1

Phylocode?

  • The movement has inspired a lot of controversy and hostility.

  • As of right now, it is generally considered an unstable substitute for the Linnaean system.

  • Future?


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