History of Systematics

The history of taxonomy and systematics goes back to the beginning of mankind. Since the dawn of civilization, human beings have been anxious to unravel the mystery of nature, the flora and fauna, the sun and the star etc. In the beginning, taxonomy was based on the experience and knowledge of local people about the vast biodiversity around them. However, no authentic history of taxonomy has been written in the ancient literature. Only superficial and descriptive attempts have been made from time to time to give an idea of history of taxonomy in the standard histories of zoology and botany. Since that time one can distinguished at least six historical periods or levels of increasing knowledge and understanding which has led to the development of modern science of taxonomy and systematics. These periods are sharply separated from each other and sometimes various trends are concurrent during a single period.

First Period: Pre Linnaean Taxonomy:

In the Vedas and Upanishads (1500 BC to 600 BC) the earliest description of classification of plants and animals has been mentioned and several technical terms have been used to describe different plants and their parts. Early Indian scholars like Charaka and Shushruta had described some of the medicinal plants at that time.

Native of even the most primitive tribes may be excellent naturalists, with specific names for local trees, mammals, birds, fishes and the conspicuous or edible invertebrates. A tribe in Papuans in the mountain of New Guinea was found to have 137 specific names for 138 species of birds. Only one species was with another. Often the nomenclature of such tribes is clearly binominal; hence it is not sole invention of Linnaeus.

Early Greek scholars notably Hippocrates (460 – 377BC) and Democritus (465 – 370BC) though described different animals but in their literature there was no conclusive evidence of useful classification.

Some of the major contributions of notable Pre Linnaean taxonomists are –

Aristotle (384 – 322 B.C.): A good beginning of biosystematics or taxonomy was made by Aristotle. He emphasized that animals can be classified according to their way of living, actions, habits, and organization of body parts. He divided the animal kingdom into two major divisions, i.e., Anaima and Enaima. In anaima he included all invertebrates without RBCs, e.g., Coelenterates, Arthropods and Mollusccs. He included all Vertebrates with RBCs in Enaima. Enaima are again divided into two subdivisions, i.e., Oviparous and viviparous. He was the first to distinguish mandibulate from haustillate type. The Insect order like Coleoptera, Diptera and Psychae (Now Lepidoptera) were created by him. Aristotle also established different categories using certain characteristic features, viz., animals with blood versus animals without blood, two footed versus four footed, hairy versus feathered conditions and animals with or without outer shell etc. Aristotle dissected hundreds of animals to know their anatomy and showed that dolphin is a mammal, not afish. He also mentioned the major groups of animals like birds, fishes, whales and insects. Aritotelian taxonomy proceeds by logical sub division, by the presence or absence of chosen features. Aristotle’s criteria of animal classification dominated the field of systematic for well over 2000 years. Aristotle’s book “de Anima was translated into Arabic in the year 1172 Ibn by Rushd. Threodore Gaza translated the first Lain edition of the present system of identification reflects from the Aristotelian process and that is why Aristotle is called “father of classification”.

Theophrastus (370 – 285 B.C.): Theophrastus was a student of Aristotle and he is known for plant classification. He described 480 species of plant species in his book “The Historia Plantarum”.

In the late 15^th century, several authors tried to arrange plants and animals according to the principles of logical division. Some of the important contributions are mentioned below.

Guillaume Rondelet (1507), Willium Turner (1508) and Pierre Belon (1517-1564) studied and catalogued birds on the basis of adaptations, such as aquatic birds, wading birds, birds of prey, perching birds and terrestrial birds.

The Swiss scientist, Conrad Von Gesner (1519-1603) clearly described many animals in his book “Historia Animalia”.

Caesalpino (1519 – 1603): Caesalpino was an Italian taxonomist and published his book “The Plantis” in the year 1583, where he mentioned 1500 species of Plants. His classification was based on growth habit together with fruit and seed form. He introduced the sophisticated hierarchy of class, sections, genus and species and arranged the different plant species in graded order. Some of his group like the families Brassicaceae and Asteraceae are still recognized.

Gesner (1551) and Aldrovandi (1600) wrote encyclopedia on animals.

Marcello Malpighi (1583) modified the hierarchical system of animals.

John Ray (1626 – 1705): John Ray was one of the most notable Pre Linnaean taxonomist. The first important works on systematic on both and plants was initiated by him. He published his most interesting systematic work on his book “Synopsis Methodica Animalium Quadruped et Serpentini Generis” in 1693 and his most important contribution was the establishment of species as the ultimate unit of taxonomy. He first gave the good definition of species as “a reproductive unit”. He divided animals into having blood and bloodless. The former was further divided into gills and those with lungs.

Augustus Quirinus Rivinus (1652-1723) introduced the category of order while classifying plants on the basis of flowering.

During the later part of the 16^th century and the early part of the 17^th century, anatomy was considered as the basis of classification and the careful study of animals started. Workers like Fabricius (1537-1619), Petrus Severinus (1580-1656), Willium Harvey (1557-1657) and Edward Tyson (1649-1708) brought this into practice.

The improvement in the field of microscopy led the classification system more progressive during this period. The prominent workers of that time were Marcelo Malpighi (1626-1694), Jan Swanmerdam (1637-1680) and Robert Hooke (1635-1702).

However, during this Pre Linnaean period Botanists were far ahead of Zoologists.

Second Period: Linnaeus and his Contemporaries.

Around the 17^th century, animal taxonomy made little progress except the work of Willughby (1635-1672) on birds and that of Reaumur (1683-1757) on insects. However, during 18^th century, the works of Linnaeus and his followers helped systematics to blossom further. He was the first to introduce the hierarchic system of classification. His greatest contribution to systematic was the use of binomial (now binominal) nomenclature for all species of plants in his book “Species Plantarum” in 1753 and of animals in the 10th edition of “Systema Naturae” in 1758. It is relevant to mention that Bauhins, who lived nearly two hundred before Linnaeus, used the binominal nomenclature in various forms. On the basis of similarity and difference in the organization of animals Linnaeus gave a concrete concept of hierarchical classification system. Due to such immense significant contributions he is rightly called as “father of taxonomy”.

Michel Adanson (1727 – 1806), a French Botanist and rival of Linnaeus stressed upon the observation and comparison of as many as character as possible. His concept has now been extended to a new type of taxonomy called “Numerical taxonomy”.

Third Period: From “Systema Naturae” to “Origin of Species”.

The hundred years between “Systema Naturae” (1758) to Darwin’s “Origin of Species” (1859) was a period of delicate but steady transition. During this period criticism and improvements of the Linnaean system was continued.

Lamarck (1744 – 1829): Lamark published seven volumes of “Histoire des Animaux Sans Vertebres”. He is also famous for his book “Philosophique Zoologique (1809) for his book. He also published the book “Flora Francoise” in which mentioned he mentioned his concept of natural classification. Linnaeus arranged the animals from simpler to complex ones on the basis of evolution. He divided the animal kingdom into three sections and these were further divided into classes. He was the first to introduce phylogeny in systematic.

Cuvier (1769 – 1832): Cuvier emphasized on inclusion of comparative anatomy to the systematic and he was the first to include fossil form into the classification.

A steady but enormous numbers of animals are characterized during this period. The local naturalists are replaced by specialists, who studied the particular group of organisms.

Fourth Period: (Darwin and Phylogeny).

In the fourth period three great ideas were emerged into the field of systematic.

1. Von Baer (1792 – 1876): Von Baer put forwarded the “Von Baer’s Law” in 1822. According to this law “the younger the embryo the more closely did it resemble other embryos of the same stage of development”

2. Ernst Hackel (1834 – 1919): Ernst Haeckel postulated the “Recapitulation Theory” in 1866. According to this theory an animal during its development recapitulated the stages of its ancestral evolution.

3. Charles Darwin (1809 – 1822): The theory of Natural Selection was put forwarded by Darwin and Wallace in 1859. According to them natural groups exist because the members of such group had descended from a common ancestor.

All these theories give intellectual justification to the taxonomic procedures.

With the discovery of large number of species during this period brought a lot of discredit to the taxonomy.

Fifth Period: population Systematics.

This period is characterized by the study of evolution within species instead study of evolution of the higher taxa. The typological species concept was replaced by dynamitic polytypic species concept. Species were no longer considered as fixed entity, but rather as polytypic, consisting of many sub species and local populations, each differing from each other and each showing considerable variability within itself. This greatest development of modern taxonomy started around the 1930s, when the workers realized that the Linnaean species based on one or two specimens are not as perfect as those which based on population studies.

The early Mendelians (De Vries and Bateson) emphasized the role of large mutations and thought that they produce new species by a single step. They minimize the role of the environment, even as a selective agent. The geneticists began to appreciate extreme importance of small and very small genetic changes and the concept of mutation was extended to include these.

Goldschmidt (1940), Sumner (1934) and Dobzhansky (1937) combined taxonomy and genetics together to open a new branch of science called “Population genetics”. Thus Lamarkian thinking of taxonomy is replaced by population genetics. Due to this Mayr (1942) considered species as “group of interbreeding natural population”. This resulted in greater simplification of classification of many animal groups.

New terms like “new systematic” (Huxley, 1940) and biosystematics (Camp and Gilly, 1943) were added to extend the taxonomic theory. The new systematic led to the reevaluation of the species concept from the biological point of views. The taxonomists started from the museum to the field to study various characteristics of the living animals, namely, behaviour, sound, ecology, genetics, zoogeography, physiology, and biochemistry etc.

Followings are some other important events of this period:

1. The 1^st “International Zoological Congress” adopted the Blanchard Code in 1889.

2. In 1900 Mendel”s Laws of Inheritance was rediscovered.

3. In 1940 “International Commission on Zoological Nomenclature (ICZN)” was formed.

4. In 1913 plenary powers were granted To “International Commission on Zoological Nomenclature”.

5. In 1944 Ernst Mayr published his book, “Systematics and the Origin of Species”, this book emphasized that taxonomists must study the process of speciation rather than just its products.

The present day taxonomist can no longer afford to remain in a watertight compartment as in the past, quite oblivious of the progress made in the other aspects of biological science.

Sixth Period: Current Trends.

The current trend of systematics dealt almost exclusively with the species level. Macrcrotaxonomy was neglected which made little conceptual progress from the 1950s to 1970s. The current sixth period is characterized by the following three important developments.

1. The whole theory of taxonomy is examined and renewed (Simpson,1961; Gunther, 1962, Mayr,1965)

2. The use of electronic computers and associated endeavors to revive a nominalistic approach to taxonomy Sokal and Sneath, (1963).

3. The vigorous introduction biochemical approach by molecular biologists and development of numerous molecular techniques for testing the proximity of phylogenetic relationship. Comparative ethology likewise has stimulated a deeper interest in taxonomy.